BBC considering HDTV rollout

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<http://www.digitalspy.co.uk/article/ds14311.html>

IIRC, 576p is defined as HDTV in Australia.

Kirk Bayne
alt.video.digital-tv Home Page
<http://www.geocities.com/lislislislis/avdtv.htm>
 
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K. B. wrote:

> <http://www.digitalspy.co.uk/article/ds14311.html>
>
> IIRC, 576p is defined as HDTV in Australia.

Since the article states lack of available content is one of the
problematic issues, it's a no-brainer that switching to 60hz (1080i,
720p) would facilitate the change, enabling immediate HDTV telecasts of
increasing portions of current and ongoing American programing, which
I'm aware is very popular in the UK.

576p requires nothing more than display devices with line-doubling and
perhaps frame doubling (to 100hz) capacity. This has been available
from Faroudja for several years. I've heard mixed comments re the 100hz
TVs sold in Europe. Obviously they would eliminate the flicker
associated with 50hz; however, if the rescaling (especially for
interlace-video sourced material) is not done well the results might be
less than stellar.

And it's well known that modern TVs sold in Britain usually have
multi-scan capability (60hz for NTSC [or so-called PAL-60, aka
Pseudo-PAL] sources).

Even in the US and Canada, multi-scan capability is effectively standard
for HDTV receivers, accommodating 480i, 480p and 1080i sources. Some
HDTVs here now also accept 720p, though most (such as the current Sony
XBRs) convert it to 1080i. [Last I heard, Princeton Graphics was the
only US manufacturer to produce TVs which displayed native 720p.]

Obviously, Europe should have a higher refresh rate than 50hz for HDTV,
though future sets obviously will need to accommodate legacy 50hz sources.






C.
 

aztech

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Apr 13, 2004
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"manitou910" <manitou910@rogers.com> wrote in message
news:QYtjc.3220$EPt1.3179@news01.bloor.is.net.cable.rogers.com...
> K. B. wrote:
>
> > <http://www.digitalspy.co.uk/article/ds14311.html>
> >
> > IIRC, 576p is defined as HDTV in Australia.
>
> Since the article states lack of available content is one of the
> problematic issues, it's a no-brainer that switching to 60hz (1080i,
> 720p) would facilitate the change, enabling immediate HDTV telecasts of
> increasing portions of current and ongoing American programing, which
> I'm aware is very popular in the UK.

That's a question of physically producing enough material that people want
to watch rather than technical problems in converting existing programming.

You'll find that 50Hz broadcasts out-populate 60Hz regions by quite degree,
that's quite a back library of programming to obsolete or standards convert
for the sake of imports from other regions.

Most decently produced US shows have replaced film with 24p HiDef so the
frame-rate issue isn't a problem, if you're watching CSI, '24' etc in HD in
the US then you're already watching converted material (your set will
hopefully pull-down). We already receive very nice down-conversions of HD
material for 25fps, it doesn't matter if this is 576i, 720p, 1080i.

I've watched Euro1080 (50Hz) on a plasma and it's not an issue, the set
wasn't actually scanning at 50Hz.

Az.
 
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manitou910 wrote:
> K. B. wrote:
>
>> <http://www.digitalspy.co.uk/article/ds14311.html>
>>
>> IIRC, 576p is defined as HDTV in Australia.
>
> Since the article states lack of available content is one of the
> problematic issues, it's a no-brainer that switching to 60hz (1080i,
> 720p) would facilitate the change, enabling immediate HDTV telecasts
> of increasing portions of current and ongoing American programing,
> which
> I'm aware is very popular in the UK.

Err - the 50/60 issue is a non-issue. A lot of US drama is shot 1080/24p
isn't it - which we have no problems watching in 576/50i, 576/25p, 1080/50i
etc. with the 4% speed-up we are used to when watching 24fps film material.
We don't have the 24p/60i 3:2 pulldown problem either, as 24p/50i can be
done 2:2 with the speed-up.

Similarly the UK HDTV material shot 1080/25p is slowed down for the US
market and run as 1080/24p (or then 3:2ed to 1080/60i)

Where frame rate conversion is required (say from 60i/p to 50i/p) standards
convesion is improving now to the point where 50->60 and 60->50 conversion
is more transparent than MPEG2 encoding... (i.e. more motion artefacts are
introduced by the MPEG process than the conversion) Using phase correlation
techniques especially means it is not a major issue.

>
> 576p requires nothing more than display devices with line-doubling and
> perhaps frame doubling (to 100hz) capacity.

576/50p requires at worst 576/50p acquisition gear - which is rare. I think
it is more common to shoot 1080/50i and then downconvert to 576/50p, or
1080/25p frame doubled? Of course you can also TK 25fps film (sped up 24fps
film as well) to 50p by frame doubling. There is no advantage over 576/25p,
but an improvement over 576/50i if you don't vertically filter to reduce
interlace twitter.

> This has been available
> from Faroudja for several years.

Faroudja are more in the display conversion rather than standards conversion
business aren't they? Snell and Wilcox have made HD standards converters
(and some of THE best SD converters) for a while.

>I've heard mixed comments re the
> 100hz TVs sold in Europe.

This is because they are mainly used to convert 576/50i to 576/100i - with
no real progressive conversion. Some (Philips Natural Motion) even convert
material (like film) sourced 576/25p, but broadcast 576/50i, to 576/100i by
interpolating in-between fields, giving the whole film sequence a really
fluid "video" look. Very disconcerting - and the total opposite of what
many producers are now doing (shooting video at 576/50i but reducing the
temporal resolution in post-production to 576/25 to give a "film" look)...

One problem is that it is difficult to buy a direct view CRT set with
external 576/100i or 1080/50i inputs in the UK - so you are dependent on the
internal processing architecture - and can't chose your own.


> Obviously they would eliminate the flicker
> associated with 50hz; however, if the rescaling (especially for
> interlace-video sourced material) is not done well the results might
> be less than stellar.

The interpolation, motion compensation/tracking etc. used to generate twice
the number of fields is the real problem with European 100Hz sets. You get
smearing on fast motion, nasty overly vicious noise reduction, enhancement
of MPEG2 blocking and HF artefacts etc. introduced on DVD, DSat and DTT
transmissions. The RGB interconnects commonly used between DVD / Digital TV
set top boxes and European TVs means that some of the MPEG2 artefacts that
would be hidden by PAL (or NTSC) composite or S-video encoding aren't - so
you see more of the coding errors.

There have been some 576/50i to 576/50p sets sold but not many - the
benefits of progressive at 50Hz are less marked (and we don't have 3:2
issues) Some Sony DRC sets now offer 625/50i to 1250/50i or 625/100i (I've
moved to total lines from active here as this is what they are described as)
and the 1250 stuff looks better to me than the 100Hz...

>
> And it's well known that modern TVs sold in Britain usually have
> multi-scan capability (60hz for NTSC [or so-called PAL-60, aka
> Pseudo-PAL] sources).

Yep - though in many cases this is used for RGB-60 display from DVD players
these days - with no need for any PAL or NTSC composite or S-video
encoding/decoding to take place. Most TVs sold in Europe for years have
been able to lock to both 576/50i and 480/60i signals - though not all (but
most) have NTSC 3.58/4.43 or PAL-60 chroma decoding. (Meaning you get a
colour 480/60i picture in RGB but not in composite/s-video)

VHS machines do not record PAL-60 in the UK in the main, though some DVD
recorders will record NTSC 3.58 or RGB 480/60i.

>
> Even in the US and Canada, multi-scan capability is effectively
> standard for HDTV receivers, accommodating 480i, 480p and 1080i
> sources.

Isn't 480i not accommodated by multi-scan - instead the signal is
upconverted either to 480p or 1080i? It is quite a tall order to build a
tubed TV set capable of scanning both SDTV and HDTV rates. (525x60 and
1125ishx30 aren't that different, but 525x30 is quite a bit slower...)

> Some HDTVs here now also accept 720p, though most (such as
> the current Sony XBRs) convert it to 1080i. [Last I heard, Princeton
> Graphics was the only US manufacturer to produce TVs which displayed
> native 720p.]
>
> Obviously, Europe should have a higher refresh rate than 50hz for
> HDTV, though future sets obviously will need to accommodate legacy
> 50hz sources.

Hmm - 50 Hz is fine for temporal purposes (especially given many people
consider 24 Hz fine - as that is what film, and much US HD drama, runs at
for acquisition)

Just because you shoot at this rate there is no need to refresh your display
at this rate - and it is only a real issue with CRT based devices that scan
a flying spot. Film projectors double or triple expose each film frame on
projection (giving 48 or 72 Hz refresh from a 24Hz source)

Plasmas displays run at much higher sub-field rates than their source
material (they often run at 300Hz ish don't they to generate the grey
scale - along with dithering) - and LCDs and DLPs have a different refresh
dynamic, so don't appear to flicker in the same way CRTs do?

The flicker introduced by 50Hz scanning (rather than 50Hz acquisition) is a
function of CRTs - which are presumably less an issue for future HD
standards?

I think that the benefits of sticking with the same production format
(timecode compatibility, simultaneous downconversion to SDTV easily,
lighting flicker etc.) probably outweigh the benefits of moving to a
different system for the sake of it.
 
G

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Guest
Archived from groups: alt.video.digital-tv (More info?)

Stephen Neal wrote:
>>
>>>IIRC, 576p is defined as HDTV in Australia.
>>
>>Since the article states lack of available content is one of the
>>problematic issues, it's a no-brainer that switching to 60hz (1080i,
>>720p) would facilitate the change, enabling immediate HDTV telecasts
>>of increasing portions of current and ongoing American programing,
>>which I'm aware is very popular in the UK.
>
> Err - the 50/60 issue is a non-issue. A lot of US drama is shot 1080/24p
> isn't it - which we have no problems watching in 576/50i, 576/25p, 1080/50i
> etc. with the 4% speed-up we are used to when watching 24fps film material.
> We don't have the 24p/60i 3:2 pulldown problem either, as 24p/50i can be
> done 2:2 with the speed-up.

The speedup can work havoc with an elaborate soundtrack. While pitch is
no longer an issue for digital audio, a 4% speedup can drastically alter
the character of any music. It is correct, however, that most US dramas
(and comedies) are shot at 24fps and still more on film than video.

> Similarly the UK HDTV material shot 1080/25p is slowed down for the US
> market and run as 1080/24p (or then 3:2ed to 1080/60i)

This has been done for a few movies shot on digital PAL (eg, "The
Anniversary Party"), but I've never heard of UK TV shows being slowed
down for US telecasts.

> Where frame rate conversion is required (say from 60i/p to 50i/p) standards
> convesion is improving now to the point where 50->60 and 60->50 conversion
> is more transparent than MPEG2 encoding... (i.e. more motion artefacts are
> introduced by the MPEG process than the conversion) Using phase correlation
> techniques especially means it is not a major issue.

I'm very skeptical re standards conversions because I've seen so many
that looked atrocious.

After all the effort to restore "Brideshead Revisited" the NTSC
broadcasts (and DVDs) were literally unwatchable.

Ditto for the new "Forsyte Saga" (though the PAL DVDs for this were
pretty bad too).

>>576p requires nothing more than display devices with line-doubling and
>>perhaps frame doubling (to 100hz) capacity.
>
> 576/50p requires at worst 576/50p acquisition gear - which is rare. I think
> it is more common to shoot 1080/50i and then downconvert to 576/50p, or
> 1080/25p frame doubled? Of course you can also TK 25fps film (sped up 24fps
> film as well) to 50p by frame doubling. There is no advantage over 576/25p,
> but an improvement over 576/50i if you don't vertically filter to reduce
> interlace twitter.

I'd assume that with proper conversion to progressive scan, this should
work.

>>This has been available from Faroudja for several years.
>
> Faroudja are more in the display conversion rather than standards conversion
> business aren't they? Snell and Wilcox have made HD standards converters
> (and some of THE best SD converters) for a while.

Faroudja is best known for its high-end home scalers (I have one of
their NRS series feeding 720p/60 to an Ampro HD3600 CRT projector) and,
more recently, the FLI2310 chip used in certain progressive-scan DVD
players (with scaling to 720p and 1080i as well as 480p).

I'm aware that some US stations are using industrial Faroudja gear to
up-rez NTSC programs for HDTV. However I don't know exactly which
stations and/or networks are doing this, so I can't really comment.

The Faroudja NRS scaler can be set to convert PAL sources to 100hz
progressive scan. I haven't seen this, but I'd expect it would be very
good.

I'm well aware of Snell & Wilcox' reputation, but can mention that
PAL-to-NTSC conversions always look a lot better with Faroudja scaling
at the display end, than without.

>>I've heard mixed comments re the 100hz TVs sold in Europe.
>
> This is because they are mainly used to convert 576/50i to 576/100i - with
> no real progressive conversion. Some (Philips Natural Motion) even convert
> material (like film) sourced 576/25p, but broadcast 576/50i, to 576/100i by
> interpolating in-between fields, giving the whole film sequence a really
> fluid "video" look. Very disconcerting - and the total opposite of what
> many producers are now doing (shooting video at 576/50i but reducing the
> temporal resolution in post-production to 576/25 to give a "film" look)...
>
> One problem is that it is difficult to buy a direct view CRT set with
> external 576/100i or 1080/50i inputs in the UK - so you are dependent on the
> internal processing architecture - and can't chose your own.

Has their been much interest in progressive-scan DVD players in the UK?

I'm aware of them being marketed but, as you say, without compatible
displays their use would be limited.

>>Obviously they would eliminate the flicker
>>associated with 50hz; however, if the rescaling (especially for
>>interlace-video sourced material) is not done well the results might
>>be less than stellar.
>
> The interpolation, motion compensation/tracking etc. used to generate twice
> the number of fields is the real problem with European 100Hz sets. You get
> smearing on fast motion, nasty overly vicious noise reduction, enhancement
> of MPEG2 blocking and HF artefacts etc. introduced on DVD, DSat and DTT
> transmissions. The RGB interconnects commonly used between DVD / Digital TV
> set top boxes and European TVs means that some of the MPEG2 artefacts that
> would be hidden by PAL (or NTSC) composite or S-video encoding aren't - so
> you see more of the coding errors.

Rescaling is always a balancing act. If the source is technically poor
it will likely look worse on a high-resolution display.

> There have been some 576/50i to 576/50p sets sold but not many - the
> benefits of progressive at 50Hz are less marked (and we don't have 3:2
> issues) Some Sony DRC sets now offer 625/50i to 1250/50i or 625/100i (I've
> moved to total lines from active here as this is what they are described as)
> and the 1250 stuff looks better to me than the 100Hz...
>
>>And it's well known that modern TVs sold in Britain usually have
>>multi-scan capability (60hz for NTSC [or so-called PAL-60, aka
>>Pseudo-PAL] sources).
>
> Yep - though in many cases this is used for RGB-60 display from DVD players
> these days - with no need for any PAL or NTSC composite or S-video
> encoding/decoding to take place. Most TVs sold in Europe for years have
> been able to lock to both 576/50i and 480/60i signals - though not all (but
> most) have NTSC 3.58/4.43 or PAL-60 chroma decoding. (Meaning you get a
> colour 480/60i picture in RGB but not in composite/s-video)
>
> VHS machines do not record PAL-60 in the UK in the main, though some DVD
> recorders will record NTSC 3.58 or RGB 480/60i.
>
>>Even in the US and Canada, multi-scan capability is effectively
>>standard for HDTV receivers, accommodating 480i, 480p and 1080i
>>sources.
>
> Isn't 480i not accommodated by multi-scan - instead the signal is
> upconverted either to 480p or 1080i? It is quite a tall order to build a
> tubed TV set capable of scanning both SDTV and HDTV rates. (525x60 and
> 1125ishx30 aren't that different, but 525x30 is quite a bit slower...)

Yes. The HDTVs don't display native NTSC; they rescale to 480p or 960i
(a few may now do 1080i, or 720p). My point was that they could handle
a range of different standards.

>>Some HDTVs here now also accept 720p, though most (such as
>>the current Sony XBRs) convert it to 1080i. [Last I heard, Princeton
>>Graphics was the only US manufacturer to produce TVs which displayed
>>native 720p.]
>>
>>Obviously, Europe should have a higher refresh rate than 50hz for
>>HDTV, though future sets obviously will need to accommodate legacy
>>50hz sources.
>
> Hmm - 50 Hz is fine for temporal purposes (especially given many people
> consider 24 Hz fine - as that is what film, and much US HD drama, runs at
> for acquisition)
>
> Just because you shoot at this rate there is no need to refresh your display
> at this rate - and it is only a real issue with CRT based devices that scan
> a flying spot. Film projectors double or triple expose each film frame on
> projection (giving 48 or 72 Hz refresh from a 24Hz source)
>
> Plasmas displays run at much higher sub-field rates than their source
> material (they often run at 300Hz ish don't they to generate the grey
> scale - along with dithering) - and LCDs and DLPs have a different refresh
> dynamic, so don't appear to flicker in the same way CRTs do?
>
> The flicker introduced by 50Hz scanning (rather than 50Hz acquisition) is a
> function of CRTs - which are presumably less an issue for future HD
> standards?
>
> I think that the benefits of sticking with the same production format
> (timecode compatibility, simultaneous downconversion to SDTV easily,
> lighting flicker etc.) probably outweigh the benefits of moving to a
> different system for the sake of it.

If new display formats eliminate flicker associated with PAL (even NTSC)
and do so without compromising other technical aspects this is the way
to go IMO.

Someone has even suggested a 120hz standard for American HDTV which
would be fully compatible with both legacy 60hz NTSC video and all
movies and 24fps film-sourced TV series (for which each frame would be
shown five times, eliminating 3:2 pulldown artifacts).

My major issue with 50hz standards is the excess flicker for standard
displays, and the fact that all movies and film-sourced American TV
series must be speeded up which may cause serious audio compromise.






C.
 
G

Guest

Guest
Archived from groups: alt.video.digital-tv (More info?)

manitou910 wrote:
> Stephen Neal wrote:
>>>
>>>> IIRC, 576p is defined as HDTV in Australia.
>>>
>>> Since the article states lack of available content is one of the
>>> problematic issues, it's a no-brainer that switching to 60hz (1080i,
>>> 720p) would facilitate the change, enabling immediate HDTV telecasts
>>> of increasing portions of current and ongoing American programing,
>>> which I'm aware is very popular in the UK.
>>
>> Err - the 50/60 issue is a non-issue. A lot of US drama is shot
>> 1080/24p isn't it - which we have no problems watching in 576/50i,
>> 576/25p, 1080/50i etc. with the 4% speed-up we are used to when
>> watching 24fps film material. We don't have the 24p/60i 3:2 pulldown
>> problem either, as 24p/50i can be done 2:2 with the speed-up.
>
> The speedup can work havoc with an elaborate soundtrack. While pitch
> is no longer an issue for digital audio, a 4% speedup can drastically
> alter the character of any music. It is correct, however, that most
> US dramas (and comedies) are shot at 24fps and still more on film
> than video.

Given that we've put up with the speed-up on 24p material since about 1936,
when we launched our 50i TV system (405/50i), I think we're used to it in
the UK. With digital pitch correction the 4% speed-up is normally not an
issue. I agree it changes the nature of music programmes - but these are
often shot 60i or 50i rather than 24p so there is no speed change (as a
standards conversion rather than speed change is used)

>
>> Similarly the UK HDTV material shot 1080/25p is slowed down for the
>> US market and run as 1080/24p (or then 3:2ed to 1080/60i)
>
> This has been done for a few movies shot on digital PAL (eg, "The
> Anniversary Party"), but I've never heard of UK TV shows being slowed
> down for US telecasts.

The BBC series Rockface was shot 1080/25p on HDCam and was co-produced with
a US broadcaster/studio. The 25p material was slowed to 24p for the US
transmissions. (Presumably it was then either broadcast 24p or 60i with 3:2
pull-down)

I imagine that UK drama shot 25p will follow this model of slow-down to 24p.
Of course 50i drama will still be converted to 60i with no speed change.

>
>> Where frame rate conversion is required (say from 60i/p to 50i/p)
>> standards convesion is improving now to the point where 50->60 and
>> 60->50 conversion is more transparent than MPEG2 encoding... (i.e.
>> more motion artefacts are introduced by the MPEG process than the
>> conversion) Using phase correlation techniques especially means it
>> is not a major issue.
>
> I'm very skeptical re standards conversions because I've seen so many
> that looked atrocious.

They have got massively better in recent years. You get what you pay for.
In the last 3 or 4 years the Snell and Wilcox Alchemist PhC and Platinum
conversions approach transparency - even on fast moving sports.

We also have the problem in the UK of having to un-pick 3:2 pull-down of US
film transfers, as the non-continuous movement confuses motion tracking,
instead the 3rd redundant field has to be detected and removed. So we go
from 60i 3:2 to 48i 2:2 using DEFT (Digital Electronic Film Transfer -
another S&W technique) and then speed up to 50i. It works really well on US
film drama edited on 480/60i tape. You only notice the slight softness
difference between 480 and 576 - which is far less obvious than the 3.58NTSC
vs 4.43PAL softness difference.

>
> After all the effort to restore "Brideshead Revisited" the NTSC
> broadcasts (and DVDs) were literally unwatchable.

Well the broadcasts will have been made on 1980s converters. I'm
disappointed that the DVDs were standards converted at all - AIUI Brideshead
was shot and edited on film so could have been telecined from the film
masters to 480/60i or 480/24p for DVD mastering. You'd have probably had a
slow-down if this were the case as I suspect the UK TV production will have
been shot 25fps film rather than 24fps (as in Europe film-for-TV is normally
shot at 25 rather than 24)

The chances are that if the DVD was mastered from the UK VT transfer it may
well have been the 1980s 1" C format PAL, and the telecine-ing would have
happened in the 80s as well, if it were mastered from the US broadcast
masters made in the 80s it will have had a pretty bad conversion as well I
imagine. Telecine and conversion technology has moved on a-pace since the
80s and even the mid 90s...

There are of course all the usual DVD mastering annoyances as well - too
much noise reduction, excessive compression and addition aperture correction
etc.

>
> Ditto for the new "Forsyte Saga" (though the PAL DVDs for this were
> pretty bad too).

Again - a commercial DVD release - presumably not optimised for quality.
There seem to be a massive range in quality of UK DVD releases - the good
ones are very good, the bad ones are terrible. The best feature film
transfers are sourced from 1080/24p HD masters - which are converted to
576/50i (576/25p) via scaling and speed-up.

For high quality R1 PAL video and film DVD remastering the Dr Who
Restoration Team have worked marvels. They use a BBC R&D PAL decoder to
transfer the D3 copies of the 2" or 1" video masters (which leaves almost no
composite artefacts), and where possible re-transfer and re-grade any film
inserts that remain as film in the BBC archive. The quality is often
stunningly good.

>
>>> 576p requires nothing more than display devices with line-doubling
>>> and perhaps frame doubling (to 100hz) capacity.
>>
>> 576/50p requires at worst 576/50p acquisition gear - which is rare.
>> I think it is more common to shoot 1080/50i and then downconvert to
>> 576/50p, or 1080/25p frame doubled? Of course you can also TK 25fps
>> film (sped up 24fps film as well) to 50p by frame doubling. There is
>> no advantage over 576/25p, but an improvement over 576/50i if you
>> don't vertically filter to reduce interlace twitter.
>
> I'd assume that with proper conversion to progressive scan, this
> should work.
>

576/50i to 576/50p should be OK if the de-interlacing processing is high
enough quality. 576/50i to 576/25p will look horrid though, as you are
chucking away half of the motion information. To reduce display flicker
then you would either have to move to 576/100p (quite a high scan rate) or
576/100i (which will have some interlace artefacts - but these will be at
50Hz not 25Hz as is the case with 50i)

>>> This has been available from Faroudja for several years.
>>
>> Faroudja are more in the display conversion rather than standards
>> conversion business aren't they? Snell and Wilcox have made HD
>> standards converters (and some of THE best SD converters) for a
>> while.
>
> Faroudja is best known for its high-end home scalers (I have one of
> their NRS series feeding 720p/60 to an Ampro HD3600 CRT projector)
> and, more recently, the FLI2310 chip used in certain progressive-scan
> DVD players (with scaling to 720p and 1080i as well as 480p).

Yep -scaling rather than conversion - i.e. the field/frame rates are not
changing? (Apart from 24 to 60 which is a 3:2 conversion rather than
anything more complex?)

In other words scalers used to get between 480i to 480p to 720p to 1080i at
either 30 or 60 (or 24 with 3:2)

[snip]

If we were to move to 60i, 60p or 30p production in Europe we'd need to use
field/frame rate tstandards conversion, rather than scaling, permanently to
convert to or from 576/50i for upconversion of SDTV material, and
downconversion of HD. Whilst this is now a high quality process it is also
a much more expensive process than scaling - especially if you have to do it
for all of your outlets, especially regional ones. Far better to only
field/frame rate convert the small amount of imported material rather than
your entire archive and continued SDTV production base?

Given that much of what the UK would import from the US would be 24p, rather
than 30p or 60i, that would be easily converted to 48i then sped up to 50i
for playout without conversion. We'd then only need to do a standards
conversion for the 30p, 60i or 60p material such as sport, gameshows etc.
which are far less common and popular imports than the 24p stuff.


>>> I've heard mixed comments re the 100hz TVs sold in Europe.
>>
>> This is because they are mainly used to convert 576/50i to 576/100i
>> - with no real progressive conversion. Some (Philips Natural Motion)
>> even convert material (like film) sourced 576/25p, but broadcast
>> 576/50i, to 576/100i by interpolating in-between fields, giving the
>> whole film sequence a really fluid "video" look. Very disconcerting
>> - and the total opposite of what many producers are now doing
>> (shooting video at 576/50i but reducing the temporal resolution in
>> post-production to 576/25 to give a "film" look)...
>>
>> One problem is that it is difficult to buy a direct view CRT set with
>> external 576/100i or 1080/50i inputs in the UK - so you are
>> dependent on the internal processing architecture - and can't chose
>> your own.
>
> Has their been much interest in progressive-scan DVD players in the
> UK?

Not huge amounts - though quite a few players are available. However there
are very few 50p CRT sets on the market. Prog scan DVDs are mainly used
with inherently progressive display devices that can't display interlace
native - plasmas, DLPs, LCDs etc - which have 576/50p input compatibility.

However the vast majority of TV sales in the UK are still direct-view CRTs -
predominantly in the sub 28" diagonal. However increasingly >21" sets sold
are 16:9 CRT shape - it is very difficult to buy a 4:3 set bigger than 21"
in most UK stores these days. 32" is the largest mass market 16:9 CRT -
though 36"ers are now on offer.

Plasmas are growing in popularity, though like projectors they are still
quite niche.

>
> I'm aware of them being marketed but, as you say, without compatible
> displays their use would be limited.

100i rather than 50p is the marketing thing for direct-view CRTs in the UK.
Annoying as I would rather watch an unprocessed 50i picture - but it is
difficult to buy a high-end TV without processing to 100i now... (And only
the higher end sets have multiple RGB inputs etc.)

>
>>> Obviously they would eliminate the flicker
>>> associated with 50hz; however, if the rescaling (especially for
>>> interlace-video sourced material) is not done well the results might
>>> be less than stellar.
>>
>> The interpolation, motion compensation/tracking etc. used to
>> generate twice the number of fields is the real problem with
>> European 100Hz sets. You get smearing on fast motion, nasty overly
>> vicious noise reduction, enhancement of MPEG2 blocking and HF
>> artefacts etc. introduced on DVD, DSat and DTT transmissions. The
>> RGB interconnects commonly used between DVD / Digital TV set top
>> boxes and European TVs means that some of the MPEG2 artefacts that
>> would be hidden by PAL (or NTSC) composite or S-video encoding
>> aren't - so you see more of the coding errors.
>
> Rescaling is always a balancing act. If the source is technically
> poor it will likely look worse on a high-resolution display.

Yep - though a lot of 100Hz introduces as many artefacts as it also exposes!

[snip]

> If new display formats eliminate flicker associated with PAL (even
> NTSC) and do so without compromising other technical aspects this is
> the way to go IMO.

Technically the flicker is nothing to do with PAL - that is only the chroma
standard!

I think you have to divorce your display rate and your broadcast rate don't
you?

I think that we'd be best suited eventually moving to 1080/25p and 1080/50p
broadcast standards - display on direct CRTs would be at 100i (with
interlace artefacts at 50Hz) - but display on plasma, DLP, LCD etc would be
at 50p without major flicker (as the flicker is more a CRT scanning raster
thing which isn't inherent in other display technologies?)

>
> Someone has even suggested a 120hz standard for American HDTV which
> would be fully compatible with both legacy 60hz NTSC video and all
> movies and 24fps film-sourced TV series (for which each frame would be
> shown five times, eliminating 3:2 pulldown artifacts).

Yep - presumably retaining 24p and 60i/p transmission systems and only
up-converting to 120p or i in the display device by frame repetition?

>
> My major issue with 50hz standards is the excess flicker for standard
> displays, and the fact that all movies and film-sourced American TV
> series must be speeded up which may cause serious audio compromise.
>

Have you watched 50i or 25p material on a non-CRT device? The audio
compromise is only an issue for the small amount of imported stuff we have -
our native stuff has none. The major UK networks show quite small amounts
of imported material - though feature films I agree are compromised
slightly, but I personally find 3:2 more annoying than the audio change!

Steve
 
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Stephen Neal wrote:

>
> Where frame rate conversion is required (say from 60i/p to 50i/p) standards
> convesion is improving now to the point where 50->60 and 60->50 conversion
> is more transparent than MPEG2 encoding... (i.e. more motion artefacts are
> introduced by the MPEG process than the conversion) Using phase correlation
> techniques especially means it is not a major issue.

I don;t understand how this conversion can be done well. Consider
the typical scenario when I watch a 50->60 Hz conversion: A F1 car
is travelling down the track to 100 mph, with buildings and fences
with narrow highly visible poles moving rapidly, as the camera
pans to keep teh car centered. How do you fix up the 5:6 motion of
those highly visible discrete poles? Aboyt 90% of 50Hz originaled TV
is of this sort. It looks bad.



Doug McDonald
 
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manitou910 wrote:

>>> Some HDTVs here now also accept 720p, though most (such as
>>> the current Sony XBRs) convert it to 1080i. [Last I heard, Princeton
>>> Graphics was the only US manufacturer to produce TVs which displayed
>>> native 720p.]

You are talking here only legacy CRT diplays. These will dominate
the HD and all but niche markest only a couple of more years. Then
the non-scanned displays such as plasma, LCD, and DLP will be the
"norm" for all but the most budget concious. These are currently
all either 720p or, disastrously (Sony, of course), 768p. Eventually
they will be 1080p.

Doug McDonald
 
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Could somebody explain how you can change the pitch of music
without changing the speed, without totally screwing up the phase
relationships that control soundstage imaging?

Doug McDonald
 
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Stephen Neal wrote:

>>>>>IIRC, 576p is defined as HDTV in Australia.
>>>>
>>>>Since the article states lack of available content is one of the
>>>>problematic issues, it's a no-brainer that switching to 60hz (1080i,
>>>>720p) would facilitate the change, enabling immediate HDTV telecasts
>>>>of increasing portions of current and ongoing American programing,
>>>>which I'm aware is very popular in the UK.
>>>
>>>Err - the 50/60 issue is a non-issue. A lot of US drama is shot
>>>1080/24p isn't it - which we have no problems watching in 576/50i,
>>>576/25p, 1080/50i etc. with the 4% speed-up we are used to when
>>>watching 24fps film material. We don't have the 24p/60i 3:2 pulldown
>>>problem either, as 24p/50i can be done 2:2 with the speed-up.
>>
>>The speedup can work havoc with an elaborate soundtrack. While pitch
>>is no longer an issue for digital audio, a 4% speedup can drastically
>>alter the character of any music. It is correct, however, that most
>>US dramas (and comedies) are shot at 24fps and still more on film
>>than video.
>
> Given that we've put up with the speed-up on 24p material since about 1936,
> when we launched our 50i TV system (405/50i), I think we're used to it in
> the UK. With digital pitch correction the 4% speed-up is normally not an
> issue. I agree it changes the nature of music programmes - but these are
> often shot 60i or 50i rather than 24p so there is no speed change (as a
> standards conversion rather than speed change is used)
>
>>>Similarly the UK HDTV material shot 1080/25p is slowed down for the
>>>US market and run as 1080/24p (or then 3:2ed to 1080/60i)
>>
>>This has been done for a few movies shot on digital PAL (eg, "The
>>Anniversary Party"), but I've never heard of UK TV shows being slowed
>>down for US telecasts.
>
> The BBC series Rockface was shot 1080/25p on HDCam and was co-produced with
> a US broadcaster/studio. The 25p material was slowed to 24p for the US
> transmissions. (Presumably it was then either broadcast 24p or 60i with 3:2
> pull-down)
>
> I imagine that UK drama shot 25p will follow this model of slow-down to 24p.
> Of course 50i drama will still be converted to 60i with no speed change.

Most of the standards concersions I've seen were very obviously done
with the field/frame interpolation which takes portions of one
field/frame and puts it into another, which always creates ghosting and
other artifacts. While this can be minimized by additional processing,
the result is a much softer picture, and usually (though I don't
understand why) desaturated and otherwise poor color.

>>>Where frame rate conversion is required (say from 60i/p to 50i/p)
>>>standards convesion is improving now to the point where 50->60 and
>>>60->50 conversion is more transparent than MPEG2 encoding... (i.e.
>>>more motion artefacts are introduced by the MPEG process than the
>>>conversion) Using phase correlation techniques especially means it
>>>is not a major issue.
>>
>>I'm very skeptical re standards conversions because I've seen so many
>>that looked atrocious.
>
> They have got massively better in recent years. You get what you pay for.
> In the last 3 or 4 years the Snell and Wilcox Alchemist PhC and Platinum
> conversions approach transparency - even on fast moving sports.
>
> We also have the problem in the UK of having to un-pick 3:2 pull-down of US
> film transfers, as the non-continuous movement confuses motion tracking,
> instead the 3rd redundant field has to be detected and removed. So we go
> from 60i 3:2 to 48i 2:2 using DEFT (Digital Electronic Film Transfer -
> another S&W technique) and then speed up to 50i. It works really well on US
> film drama edited on 480/60i tape. You only notice the slight softness
> difference between 480 and 576 - which is far less obvious than the 3.58NTSC
> vs 4.43PAL softness difference.
>
>>After all the effort to restore "Brideshead Revisited" the NTSC
>>broadcasts (and DVDs) were literally unwatchable.
>
> Well the broadcasts will have been made on 1980s converters. I'm
> disappointed that the DVDs were standards converted at all - AIUI Brideshead
> was shot and edited on film so could have been telecined from the film
> masters to 480/60i or 480/24p for DVD mastering. You'd have probably had a
> slow-down if this were the case as I suspect the UK TV production will have
> been shot 25fps film rather than 24fps (as in Europe film-for-TV is normally
> shot at 25 rather than 24)
>
> The chances are that if the DVD was mastered from the UK VT transfer it may
> well have been the 1980s 1" C format PAL, and the telecine-ing would have
> happened in the 80s as well, if it were mastered from the US broadcast
> masters made in the 80s it will have had a pretty bad conversion as well I
> imagine. Telecine and conversion technology has moved on a-pace since the
> 80s and even the mid 90s...
>
> There are of course all the usual DVD mastering annoyances as well - too
> much noise reduction, excessive compression and addition aperture correction
> etc.

I'm fairly sure the NTSC discs were new conversions (the color was
improved, and identical to the new PAL discs). For some reason they
were just done incredibly badly. I got the PAL discs when they became
available and they are fine.

The R1/NTSC discs, though, are appalling for the unending chop-chop
arising from sub-mediocre frame/field interpolation, especially for
moderate pans and rolling credits.

>>Ditto for the new "Forsyte Saga" (though the PAL DVDs for this were
>>pretty bad too).
>
> Again - a commercial DVD release - presumably not optimised for quality.
> There seem to be a massive range in quality of UK DVD releases - the good
> ones are very good, the bad ones are terrible. The best feature film
> transfers are sourced from 1080/24p HD masters - which are converted to
> 576/50i (576/25p) via scaling and speed-up.
>
> For high quality R1 PAL video and film DVD remastering the Dr Who
> Restoration Team have worked marvels. They use a BBC R&D PAL decoder to
> transfer the D3 copies of the 2" or 1" video masters (which leaves almost no
> composite artefacts), and where possible re-transfer and re-grade any film
> inserts that remain as film in the BBC archive. The quality is often
> stunningly good.

I've noted that the quality of PAL discs seems to vary a lot, and I've
been disappointed often by the discs for UK TV series.

As you say, most movies now are mastered at 1080/24, which makes for
easy downconversion to NTSC and PAL specs.

>>>>576p requires nothing more than display devices with line-doubling
>>>>and perhaps frame doubling (to 100hz) capacity.
>>>
>>>576/50p requires at worst 576/50p acquisition gear - which is rare.
>>>I think it is more common to shoot 1080/50i and then downconvert to
>>>576/50p, or 1080/25p frame doubled? Of course you can also TK 25fps
>>>film (sped up 24fps film as well) to 50p by frame doubling. There is
>>>no advantage over 576/25p, but an improvement over 576/50i if you
>>>don't vertically filter to reduce interlace twitter.
>>
>>I'd assume that with proper conversion to progressive scan, this
>>should work.
>
> 576/50i to 576/50p should be OK if the de-interlacing processing is high
> enough quality. 576/50i to 576/25p will look horrid though, as you are
> chucking away half of the motion information. To reduce display flicker
> then you would either have to move to 576/100p (quite a high scan rate) or
> 576/100i (which will have some interlace artefacts - but these will be at
> 50Hz not 25Hz as is the case with 50i)
>
>>>>This has been available from Faroudja for several years.
>>>
>>>Faroudja are more in the display conversion rather than standards
>>>conversion business aren't they? Snell and Wilcox have made HD
>>>standards converters (and some of THE best SD converters) for a
>>>while.
>>
>>Faroudja is best known for its high-end home scalers (I have one of
>>their NRS series feeding 720p/60 to an Ampro HD3600 CRT projector)
>>and, more recently, the FLI2310 chip used in certain progressive-scan
>>DVD players (with scaling to 720p and 1080i as well as 480p).
>
> Yep -scaling rather than conversion - i.e. the field/frame rates are not
> changing? (Apart from 24 to 60 which is a 3:2 conversion rather than
> anything more complex?)
>
> In other words scalers used to get between 480i to 480p to 720p to 1080i at
> either 30 or 60 (or 24 with 3:2)

Faroudja scalers rescale all NTSC sources to 60 frames. For 24fps
source material, the additional field generated by the 3:2 pulldown is
discarded, a progressive frame is created by combining the two fields
from each movie frame, and the result is output at 60fps, reinstating
the pulldown but eliminating all interlace artifacts.

> If we were to move to 60i, 60p or 30p production in Europe we'd need to use
> field/frame rate tstandards conversion, rather than scaling, permanently to
> convert to or from 576/50i for upconversion of SDTV material, and
> downconversion of HD. Whilst this is now a high quality process it is also
> a much more expensive process than scaling - especially if you have to do it
> for all of your outlets, especially regional ones. Far better to only
> field/frame rate convert the small amount of imported material rather than
> your entire archive and continued SDTV production base?
>
> Given that much of what the UK would import from the US would be 24p, rather
> than 30p or 60i, that would be easily converted to 48i then sped up to 50i
> for playout without conversion. We'd then only need to do a standards
> conversion for the 30p, 60i or 60p material such as sport, gameshows etc.
> which are far less common and popular imports than the 24p stuff.

I realize we can't expect broadcast networks to shange their ways, but
there is no reason for serious home theater people to be short-changed.

Ideally all video sources should be displayed in their original format.

>>>>I've heard mixed comments re the 100hz TVs sold in Europe.
>>>
>>>This is because they are mainly used to convert 576/50i to 576/100i
>>>- with no real progressive conversion. Some (Philips Natural Motion)
>>>even convert material (like film) sourced 576/25p, but broadcast
>>>576/50i, to 576/100i by interpolating in-between fields, giving the
>>>whole film sequence a really fluid "video" look. Very disconcerting
>>>- and the total opposite of what many producers are now doing
>>>(shooting video at 576/50i but reducing the temporal resolution in
>>>post-production to 576/25 to give a "film" look)...
>>>
>>>One problem is that it is difficult to buy a direct view CRT set with
>>>external 576/100i or 1080/50i inputs in the UK - so you are
>>>dependent on the internal processing architecture - and can't chose
>>>your own.
>>
>>Has their been much interest in progressive-scan DVD players in the
>>UK?
>
> Not huge amounts - though quite a few players are available. However there
> are very few 50p CRT sets on the market. Prog scan DVDs are mainly used
> with inherently progressive display devices that can't display interlace
> native - plasmas, DLPs, LCDs etc - which have 576/50p input compatibility.
>
> However the vast majority of TV sales in the UK are still direct-view CRTs -
> predominantly in the sub 28" diagonal. However increasingly >21" sets sold
> are 16:9 CRT shape - it is very difficult to buy a 4:3 set bigger than 21"
> in most UK stores these days. 32" is the largest mass market 16:9 CRT -
> though 36"ers are now on offer.
>
> Plasmas are growing in popularity, though like projectors they are still
> quite niche.
>
>>I'm aware of them being marketed but, as you say, without compatible
>>displays their use would be limited.
>
> 100i rather than 50p is the marketing thing for direct-view CRTs in the UK.
> Annoying as I would rather watch an unprocessed 50i picture - but it is
> difficult to buy a high-end TV without processing to 100i now... (And only
> the higher end sets have multiple RGB inputs etc.)
>
>>>>Obviously they would eliminate the flicker
>>>>associated with 50hz; however, if the rescaling (especially for
>>>>interlace-video sourced material) is not done well the results might
>>>>be less than stellar.
>>>
>>>The interpolation, motion compensation/tracking etc. used to
>>>generate twice the number of fields is the real problem with
>>>European 100Hz sets. You get smearing on fast motion, nasty overly
>>>vicious noise reduction, enhancement of MPEG2 blocking and HF
>>>artefacts etc. introduced on DVD, DSat and DTT transmissions. The
>>>RGB interconnects commonly used between DVD / Digital TV set top
>>>boxes and European TVs means that some of the MPEG2 artefacts that
>>>would be hidden by PAL (or NTSC) composite or S-video encoding
>>>aren't - so you see more of the coding errors.
>>
>>Rescaling is always a balancing act. If the source is technically
>>poor it will likely look worse on a high-resolution display.
>
> Yep - though a lot of 100Hz introduces as many artefacts as it also exposes!
>
>>If new display formats eliminate flicker associated with PAL (even
>>NTSC) and do so without compromising other technical aspects this is
>>the way to go IMO.
>
> Technically the flicker is nothing to do with PAL - that is only the chroma
> standard!
>
> I think you have to divorce your display rate and your broadcast rate don't
> you?
>
> I think that we'd be best suited eventually moving to 1080/25p and 1080/50p
> broadcast standards - display on direct CRTs would be at 100i (with
> interlace artefacts at 50Hz) - but display on plasma, DLP, LCD etc would be
> at 50p without major flicker (as the flicker is more a CRT scanning raster
> thing which isn't inherent in other display technologies?)
>
>>Someone has even suggested a 120hz standard for American HDTV which
>>would be fully compatible with both legacy 60hz NTSC video and all
>>movies and 24fps film-sourced TV series (for which each frame would be
>>shown five times, eliminating 3:2 pulldown artifacts).
>
> Yep - presumably retaining 24p and 60i/p transmission systems and only
> up-converting to 120p or i in the display device by frame repetition?

Exactly. Movies would be should with each frame repeated five times.
NTSC sources would be line doubled and frame doubled.

>>My major issue with 50hz standards is the excess flicker for standard
>>displays, and the fact that all movies and film-sourced American TV
>>series must be speeded up which may cause serious audio compromise.
>
> Have you watched 50i or 25p material on a non-CRT device?

No, only on my Sony PVM monitors, all of which are multistandard.

> The audio
> compromise is only an issue for the small amount of imported stuff we have -
> our native stuff has none. The major UK networks show quite small amounts
> of imported material - though feature films I agree are compromised
> slightly, but I personally find 3:2 more annoying than the audio change!

Feature films IMO are very seriously compromised, and this is my primary
objection re 50hz.

Assuming a multiscan display can be available, my ideal DVD player
would, first, rescale all NTSC and PAL movies to 720p using Faroudja
technology; second, discard the pulldown for NTSC and the speedup for
PAL and output a 72fps display; third, restore the audio for PAL discs
to their correct speed using a digital chip.







C.
 
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Doug McDonald wrote:

> Could somebody explain how you can change the pitch of music
> without changing the speed, without totally screwing up the phase
> relationships that control soundstage imaging?

Analog recording changes the pitch of audio if the playback speed is
changed.

Digital does not, because digital recording increases the speed (ie,
tempo) but not the content (ie, pitch).

I can't comment on phase or soundstage.








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manitou910 wrote:
> Doug McDonald wrote:
>
>> Could somebody explain how you can change the pitch of music
>> without changing the speed, without totally screwing up the phase
>> relationships that control soundstage imaging?
>
>
> Analog recording changes the pitch of audio if the playback speed is
> changed.
>
> Digital does not, because digital recording increases the speed (ie,
> tempo) but not the content (ie, pitch).
>
> I can't comment on phase or soundstage.
>
>

You did'nt even try to answer my question. How do they do this?

Doug McDonald
 
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Doug McDonald wrote:
>>
>> Where frame rate conversion is required (say from 60i/p to 50i/p)
>> standards
>> convesion is improving now to the point where 50->60 and 60->50
>> conversion
>> is more transparent than MPEG2 encoding... (i.e. more motion artefacts
>> are
>> introduced by the MPEG process than the conversion) Using phase
>> correlation
>> techniques especially means it is not a major issue.
>
> I don;t understand how this conversion can be done well. Consider the
> typical scenario when I watch a 50->60 Hz conversion: A F1 car
> is travelling down the track to 100 mph, with buildings and fences with
> narrow highly visible poles moving rapidly, as the camera
> pans to keep teh car centered. How do you fix up the 5:6 motion of those
> highly visible discrete poles? Aboyt 90% of 50Hz originaled TV
> is of this sort. It looks bad.

IMO it is never done well. Even the Snell & Wilcox systems still take
portions of each field or frame and put them in an adjacent one.

While motion artifact correction may minimize artifacts it cannot
eliminate them completely and, at best, these standards conversions from
PAL to NTSC always look soft and fuzzy.

It's important to understand that even the S&W Alchemist was likely
designed for interlace display which camouflages a multitude of sins.

With conversion to progressive scan, these conversions are brutally
unmasked, though they look least bad with Faroudja scaling.







C.
 
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In article <VYakc.28745$huU.18029@news04.bloor.is.net.cable.rogers.com>,
manitou910 <manitou910@rogers.com> writes:
> Doug McDonald wrote:
>
>> Could somebody explain how you can change the pitch of music
>> without changing the speed, without totally screwing up the phase
>> relationships that control soundstage imaging?
>
> Analog recording changes the pitch of audio if the playback speed is
> changed.
>
> Digital does not, because digital recording increases the speed (ie,
> tempo) but not the content (ie, pitch).
>
> I can't comment on phase or soundstage.
>
A really good speed conversion will still likely cause
problems. Theoretically, one might split the modulation
from the tones (al Cepstrum), but that is messy and
impercise also.

There really is no magic bullet for digital audio speed
conversion. Think of it like this:

1) The tones have to be maintained. (maintains musicality.)
2) The modulation of the tones has to be changed. (changes the timing.)

This isn't easy (or even perfectly possible.) For speech or low-fi
(maybe FM radio quality), it isn't probably too bad. I used to be
an aggressive developer, and that is something that even I wouldn't
tackle.

John
 
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John S. Dyson wrote:
=
>
> This isn't easy (or even perfectly possible.) For speech or low-fi
> (maybe FM radio quality), it isn't probably too bad.


FM radio is not low fi, at least not here in the US for the station
I listen to ... it's definately hi-fi.

Doug McDonald
 
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In article <c6rih8$2vd$2@news.ks.uiuc.edu>,
Doug McDonald <mcdonald@scs.uiuc.edu> writes:
> John S. Dyson wrote:
> =
>>
>> This isn't easy (or even perfectly possible.) For speech or low-fi
>> (maybe FM radio quality), it isn't probably too bad.
>
>
> FM radio is not low fi, at least not here in the US for the station
> I listen to ... it's definately hi-fi.
>
I meant, in comparison with CD-like quality. When I was speaking
of FM quality, I meant TYPICAL FM quality. Theoretically, you might
get 80dBSNR with <0.1% distortion over 20-15KHz, but most of the
time, that isn't true :).

John
 
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John S. Dyson wrote:
>
>
> I meant, in comparison with CD-like quality. When I was speaking
> of FM quality, I meant TYPICAL FM quality. Theoretically, you might
> get 80dBSNR with <0.1% distortion over 20-15KHz, but most of the
> time, that isn't true :).


Well, there IS the Optimud.

Doug McDonald
 
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Doug McDonald wrote:
>>
>>> Could somebody explain how you can change the pitch of music
>>> without changing the speed, without totally screwing up the phase
>>> relationships that control soundstage imaging?
>>
>> Analog recording changes the pitch of audio if the playback speed is
>> changed.
>>
>> Digital does not, because digital recording increases the speed (ie,
>> tempo) but not the content (ie, pitch).
>
> You did'nt even try to answer my question. How do they do this?

Er......, why would anyone want to change the pitch of music, other
things being equal?

And, sorry, I don't know (or need to know) how this might be done.

The earlier portions of this thread were concerned with _avoiding_ pitch
distortions resulting from the 4% speedup which analog[audio] PAL videos
and telecasts of theatrical movies create.

Digital audio at least avoids increasing the pitch.






C.
 
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manitou910 wrote:

>>
>>
>> You did'nt even try to answer my question. How do they do this?
>
>
> Er......, why would anyone want to change the pitch of music, other
> things being equal?
>
> And, sorry, I don't know (or need to know) how this might be done.
>
> The earlier portions of this thread were concerned with _avoiding_ pitch
> distortions resulting from the 4% speedup which analog[audio] PAL videos
> and telecasts of theatrical movies create.
>
> Digital audio at least avoids increasing the pitch.
>
>

My question is, how do they avoid changing the pitch
when speeding it up?

Doug McDonald
 
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In article <Pgekc.318598$2oI1.21001@twister01.bloor.is.net.cable.rogers.com>,
manitou910 <manitou910@rogers.com> writes:
> Doug McDonald wrote:
>>>
>>>> Could somebody explain how you can change the pitch of music
>>>> without changing the speed, without totally screwing up the phase
>>>> relationships that control soundstage imaging?
>>>
>>> Analog recording changes the pitch of audio if the playback speed is
>>> changed.
>>>
>>> Digital does not, because digital recording increases the speed (ie,
>>> tempo) but not the content (ie, pitch).
>>
>> You did'nt even try to answer my question. How do they do this?
>
> Er......, why would anyone want to change the pitch of music, other
> things being equal?
>
> And, sorry, I don't know (or need to know) how this might be done.
>
> The earlier portions of this thread were concerned with _avoiding_ pitch
> distortions resulting from the 4% speedup which analog[audio] PAL videos
> and telecasts of theatrical movies create.
>
> Digital audio at least avoids increasing the pitch.
>
Note that we are speaking of the necessary transforms. If you
speed up the timing, then you have to do pitch correction. Digital
audio doesn't MAGICALLY allow for variable timing without pitch
change!!! You cannot just 'clock' the signal faster, because
everything will be faster/slower similar to good old magnetic
tape.

John