Video File Formats 101

[Guest]

"QuickTime video is highly compatible with both Mac and Windows."

QuickTime files are NOT compatible with Windows. To play Quicktime files you must install the Quicktime software.
(I won't beat the dead horse by elaborating more on how horrible that software is....hmmm, though, a brilliant ad for Macs might be not making horrible PC software for Windows...I've seen Mac software..why would I want their operating system?)

 

[mitch074]

Full of incorrect suff!

MPEG-1 is both a video codec (actually early h.262) and a container format. Techniques used in video compression could also be used to compress sound waves, yelding MPEG-1 Audio layers (depending on bitrate and encapsulation: MPEG-1 Layer 2 for example is able to do 5 channels but doesn't work on samples under 32 kHz; Layer 3 can work on sound samples down to 11 kHz).

MPEG-2 uses the same encoding techniques than MPEG-1 (an MPEG-2 decoder can decode MPEG-1 encoded content, and is technically h.262) but doesn't restrict resolution (MPEG-1 can't reach 720x480, for example) and can reach higher bitrates, because the container isn't set: MPEG-1 got as far as defining checksums for each frame, packet etc. (that's why VCDs could hold more MPEG-1 data than a normal CD).

In short, MPEG 1 and 2 are two different profiles for the container, and they can be used for both audio and video (but MPEG-2 for audio concentrates on low-bitrate sound streams, that's why DVDs usually use AC3; technically, they could also use MPEG-1 layer 2, and some actually do, as it is multichannel-capable).

AVI is a container: it can interleave a video stream and zero, one or more sound streams, each encoded the way you want (it is possible to have an MPEG-1 video stream in an AVI file using AAC encoding). The main limitation of AVI is that it doesn't like variable bitrate sound streams.

Microsoft MPEG4 v1, v2 and v3 are simili-MPEG4 encoders (they predate the specification); v1 used high quality, low-motion algorithms, v2 was the opposite, v3 (beta) has a motion adaptive encoding algorithm. They are found in AVI files, true, but guess what? Windows Media Video 7 and 8 are actually v1 and v2! WMV9 is v3 out of beta (thus incompatible).

Since DivX;-) was a hacked (and slightly improved) version of that codec, replacing Microsoft's codecs with DivX;-) didn't prevent you from playing back WMV's.

MPEG-4 is an encoding scheme equivalent to h.263 baseline, on which were added some profiles; h.264 used some techniques developed in "custom profiles" MPEG-4 codecs (such as DivX 5/6 no-profile, or XviD) on top of wavelet compression, but Apple's isn't the only version of an h.264 codec: x264 is another, which can be encapsulated in AVI files. Quicktime is a container format, which was used as inspiration for the tentative MPEG-4 container format (a variant of which is .divx files).

MPEG-4 profiles are: Simple Profile, Advanced Simple Profile (with more motion vectors, adaptive quantizers per macroblock, etc.), and others; not all codecs comply with these profiles (many are limited to Simple Profile), but DivX and XviD mostly share theirs which became de-facto standards.

Microsoft's VC-1 is a slightly modified version of WMV9 to comply (better) with MPEG-4, but which isn't ISO MPEG-4 compliant.

 

[TwoDigital]

No mention of MPEG4 AVC or SMPTE VC-1? This article is a good start but there is a lot that could be added to help 'flesh-out' video codecs and help users choose.

Is there a part 2 coming soon? Don't leave us hanging with your pitch for Quicktime (which isn't a format, but a container just like AVI, or [yes, I'll say it, gulp...] Matroska.)

 

[TwoDigital]

All I can say about quicktime is... do a web search for "quicktime alternative" and you'll find a very nice rip of quicktime's core codecs and container manager exposed as (directshow?) objects so you can double-click 'em and play them back in Windows Media without Apple's extras installed on your system. That will let you play "quicktime" content in MediaCenter as well.

There's a "real alternative" too, but does anyone use those .rm/.ra files anymore?

 

[layzer253]

You also forgot to mention the difference between codecs and containers. You can have a divx codec, inside a mpg or avi container, or even an x.264 inside an avi and possible an mpg container. The extension could be .avi but it could have any number of codecs inside the video.

 

[Guest]

Here's the only guide you'll need:

.wmv and .mpeg video file extensions are the best! .
avi and .mp4 are crap!
3gpp is the worst: it downloads like crap, the whole video is blurry!

wmv & mpeg can not only be watched in EVERY DVD player (including on TV, no problems playback) you can also use them on any video editing software (like WMM and beyond) and you get great quality.

.avi files after published with Windows Movie Maker or any of my professional editing software are completely unusable: 50% of the video (lower half) is a green screen! Video is squished to the top, unwatchable!

Most mp4 files are not recognized by any of my video converters or editing software: meaning the system will not recognize them so I can't even convert them, they're not found at their location! Some mp4's will play fine but NOT on any DVD players and just like avi's are unusable to edit and load on youtube!

FLV files are horrible: they only play on the weird Media Classic Player and some of them won't even start. No other softwares (editing, playback, converters) will recognize the , again they become invisible in the computer, not found by the copy & convert system.

Now you know. You're welcome!

 

[Guest]

I always prefer mp4 with H.264. http/connerpro.com/video-codecs-containers-simplified-with-infographic/