Uhmm microsoft says that mpg is actually an avi

[dinkob]

Is this true?

I heavily question this explanation (bottom):

Credit (as explained on): http://www.microsoft.com/windows/windowsmedia/mp10/codecs.aspx

However, a file format such as Audio Video Interleaved (AVI) can contain data that is compressed by any of a number of different codecs, including the MPEG-2, DivX, or XVid codecs. AVI files can also contain data that is not compressed by any codec. Consequently, you might be able to play some AVI files and not others, depending on which codecs were used to compress the file and which codecs you have installed on your computer. For the same reason, you also might be able to play the audio portion of an AVI file, but not the video portion.


How do I determine what format a file is in?
You might be able to tell what a file's format is by looking at the file's extension (such as .wma, .wmv, .mp3, or .avi). However, there are limits to this approach.

Many programs create files with custom file extensions. And it's possible for anyone to rename a file without changing the file's format. A file with the extension .mpg or .dvr-ms, for instance, is usually just an AVI file that has been compressed by using some version of an MPEG video codec. (huh?)

[offline]

Yes, the article is correct but confusing. Mpg is not an AVI but it can be held within an AVI. This means some AVI's can be mpg.

AVI is just a wrapper that can contain different codecs, not a codec in itself. In other words AVI is just a container which holds audio and video streams in a specified structure.

The codec "contained" is identified in the RIFF header (FOURCC). Programs such as Gspot can read this header and identify the codec used.

Think of AVI as like a frozen TV dinner tray- the tray stays the same but the meals (video/audio codecs) change.

[thecoalman]

Think of AVI as like a frozen TV dinner tray- the tray stays the same but the meals (video/audio codecs) change.

I'm going to write that one down....

[redwudz]

I worry that he thinks in terms of TV dinners. That can't be a good sign.

BTW, How do I convert a 'Swanson' AVI to a 'Banquet' AVI? (American TV dinners for the uninitiated.)

I've seen many references to MPEG 4 AVIs, so I can see why people could be confused.

[offline]

AFAIK there are no TV dinners to be had in my country. At the very least the term is unknown bar those who bathe regularly in American culture. It is through said culture that I discovered the importance of this repast. The anthropologist in me sought to employ local idioms in order to maximize translation. :P

Next time I'll say it's like a box of chocolates....

[kschang]

Slightly more on the technicaly side... AVI 2.0 standard (OpenVML?) specified the whole "wrapper" idea. AVI2 also allows multiple audio streams in the same file (but still no subtitles).

Think of AVI in the same way as Matrovska Files (.MKV)

The REALLY confusing part is MP4 (MPEG4) itself is also a "wrapper" standard, in addition of being a codec standard.

[Cornucopia]

Quicktime, Real, AVI, Matroska, Windows Media (aka ASF), MPEG, and Flash are ALL multimedia container formats.

Some allow a wide variety of codecs (QT, AVI, Matroska) and some only allow their ~proprietary codecs (Real, WMV and --in a slightly different way--MPEG).

MPEG is both codec (MPG1, MPG2--MP@ML, MPG2--SP@ML, MPG4--SP@ML, MPG4--ASP@ML, etc) and a stream container (MPG1--SystemStream, MPG2--ProgramStream, MPG2--TransportStream, MPG4, etc). Sometimes, particularly in the case of audio files (MP3), you'll see the raw streams not encapsulated in the container.

OT note: AVI has capability for multiple other types of streams (subs, chaptermarks, text, midi), but they're undefined except in certain variant formats (BSplayer, DivX6)

BTW, that's OpenDML.

Scott

[lordsmurf]

AFAIK there are no TV dinners to be had in my country.

I think I'd die of starvation.