unofficial abma/aba faq
Annotated :: Single Page/Plain :: Text :: Notes

1. Preface
2. Introduction
3. Newsgroups
4. Encoding
     a. uu
     b. mime
     c. yEnc
5. Archives
     a. .rar/.r##/.part##.rar
     b. RAR recovery
     c. .ace/.c##
     d. .###
     e. .zip
6. Support Files
     a. .sfv
     b. .par/.p##
     c. .rev
     d. .idx/.sub/.ifo
     e. .smi/.ssa/.srt
     f. .nfo/.txt/.md5
7. Newsreaders
8. Posting
     a. Bad Requests
9. Auto-Posters
10. Hentai
11. Formats/codecs
     a. avi/ogm
     b. mpeg4
     c. mpg
     d. rm
     e. audio
     f. linux
12. News servers
13. Software
14. Appendices
     a. About the FAQ
     b. Mirroring the FAQ

The new home of the FAQ is http://animeusenet.org/wiki/.

This site exists only for historical/archival purposes.

11a. Multimedia Wrapper Formats (AVI & OGM)

Multimedia Wrapper Formats (AVI & OGM) [Keikai]

While the .AVI extension has often been associated with the MPEG4 codec, they are actually not the same thing. In fact, AVI files can contain codecs other than MPEG4 and there are MPEG4 codec encodes that are not ,AVI files.

.AVI files, amongst others, are wrapper formats that explain the multimedia content. They explain to the operating system what it will need to play the files. Also, they allow for synchronization between the video, audio, and other encoded information within a multimedia file, including subtitles. Modern implementations allow for multiple audio and subtitle tracks.

Nearly all multimedia files actually contain a wrapper as well and the encoded streams, however, some are not codec specific. Examples of codec specific wrapper files are .WMV, .ASF, .RM, and .QT. These are all discussed in their associated codec section of this FAQ.

.AVI (Audio-Video Interleave) Files [Keikai]

.AVI files are by far the most common multimedia file to be found in AB(M)A. And while they are generally associated with DivX files, they can actually contain streams encoded by any number of codecs. The codec(s) needed by the contained video and audio streams must already be installed to play any .AVI file. Therefore, it is necessary to be aware of what codecs an .AVI file needs. This information will often be provided by the poster of the file. If not, this FAQ lists other methods to determining the codec.

See the subtitle section for more information on displaying subtitles with AVI files.

. OGM (Ogg Media) Files [Orqyman, Keikai, xo, ed.]

Ogg Media (.OGM) files are a far more recent wrapper format than .AVI. Usually, they contain either DivX or XviD encoded video streams. .OGM files are becoming popular as they are far more adept at supporing multiple audio and subtitle streams than .AVI. As with .AVI files,you must have the codecs needed by the contained streams to play these files. Therefore, it is necessary to be aware of what codecs an .OGM file needs. This information will often be provided by the poster of the file. If not, this FAQ lists other methods to determining the codec.

Assuming the necessary video and audio codecs of the OGM file are known, and are already installed, it is also necessary to install the Ogg Vorbis Directshow filters available at http://tobias.everwicked.com/. Any DirectShow-compatible media play should then be able to play Ogg Media files. DirectX 8.0 or higher is necessary, as well.

When subtitles are encoded into the Ogg Media file, either DVobSub or SubTitDS is necessary to display them. The SubTitDS method will not work, however, for Windows 9x/ME users, and, therefore, DVobSub will be necessary.

See the subtitle section for more information on these DirectShow filters.

Some of the advantages of Ogg Media files over AVI files are:

  • Less overhead for muxing of streams than AVI
  • Multiple audio streams (nandub AVIs support a maximum of 2 audio streams)
  • Embedded Subtitles
  • Chaptering
  • Faster Keyframe Seeks
  • Ogg Vorbis may be used for audio, which many proclaim to be better than mp3 in many respects

Determining the codec inside a Wrapper File

To be added later

User Contributed Notes

2003-02-13 04:25pm
Should add a section pointing to ffdshow at http://sourceforge.net/projects/ffdshow/ This program will play allow the user to play AVIs through Windows Mediaplayer. It includes the Xvid, Divx and other codecs so it's a one stop shop.
2003-11-07 12:17am
Determining the codec inside a Wrapper File - GSpot, of course. You can download this program from it's homepage: http://www.headbands.com/gspot/.
2003-11-08 08:40am
LJ suggested that the term 'wrapper' be replaced with 'container'. I agreed that this is more accurate.
2003-12-23 09:06am
gspot doesn't show the bitrates for ogm's this program does http://sourceforge.net/projects/avi-ogminfo/
2003-12-23 09:06am
2004-03-29 09:21am
Should also perhaps add a section on .MKV, which are gradually becoming popular. Essentially an OGM with something like 1.5MB less overhead. Or maybe it's a percent. VLC plays all of the above mentioned.
2004-05-25 07:48am
I have AVI file with 2 audio streams. How can I change the AVI file to watch it with a specific stream?
2005-04-26 04:56pm
I decompress ogm audio with GOLDWAVE and input the ogm and wav file into TMPGEnc to convert to SVCD. The completed SVCD doesn't show any subtitle from the original ogm file. Can anyone show me how to encode the embedded subtitle from the ogm onto the SVCD during the conversion? Thanks very much.
2005-05-30 10:26pm
Lazy Man's Guide to OGM and Ogg Media Files http://ld-anime.subforge.net/guide/ogm-en.php
2005-06-01 03:28pm
I have found that the Core Media Player works best for me when dealing with .AVI .OGG .OGM and .MKV files.
It is especially useful for selecting from multiple audio streams.
2005-07-13 01:47am
Zoomplayer works well too.