--- formats.html Fri Mar 29 00:24:21 2002 +++ formats-gabucino.html Fri Mar 29 22:27:01 2002 @@ -15,23 +15,22 @@

It is important to clarify a common mistake. When people see a file with a -.AVI extension, they immediately conclude that it is not a MPEG file. +.AVI extension, they immediately conclude that it is not an MPEG file. That is not true. At least not entirely. Contrary to popular belief such a file can contain MPEG1 video.

You see, a codec is not the same as a file format.
-Video codecs are: MPEG1, MPEG2, DivX, Indeo5, 3ivx.
-Video formats are: MPG, AVI, ASF.
+Examples of video codecs are: MPEG1, MPEG2, DivX, Indeo5, 3ivx.
+Examples of file formats are: MPG, AVI, ASF.

In theory, you can happily put an OpenDivX video and MP3 audio -into a MPG format file. Most players will not play it, though, since -they expect MPEG1 video and MP2 audio (.MPG does not have the -necessary fields to describe its video and audio streams, like .AVI -does). Or you might put MPEG1 video into an .AVI file. FFmpeg +

In theory, you can put an OpenDivX video and MP3 audio +into an MPG format file. However, most players will not play it, since +they expect MPEG1 video and MP2 audio (unlike AVI, MPG does not have the +necessary fields to describe its video and audio streams). +Or you might put MPEG1 video into an AVI file. FFmpeg and MEncoder can create these files.

In contrast to that audio codecs and audio formats are basically the same terms.

2.1.1. Video formats

@@ -39,18 +38,20 @@

2.1.1.1. MPEG files

MPG : This is the most basic form of the MPEG file formats. It contains +

MPEG files come in different guises:

+ +

MPG: This is the most basic form of the MPEG file formats. It contains MPEG1 video, and MP2 (MPEG-1 layer 2) or rarely MP1 audio.
DAT : This is the very same format as MPG with a different extension. It is used +
DAT: This is the very same format as MPG with a different extension. It is used on Video CDs. Due to the way VCDs are created and Linux is designed, the DAT files cannot be played nor copied from VCDs as regular files. You have to use the -vcd option to play the Video CD.
VOB : This is the MPEG file format on DVDs. It is the same as MPG, plus the +
VOB: This is the MPEG file format on DVDs. It is the same as MPG, plus the capability to contain subtitles or non-MPEG (AC3) audio. It contains encoded MPEG2 video and usually AC3 audio, but DTS, MP2 and uncompressed LPCM are allowed, too.
Read the DVD section !

Series of frames form independent groups in MPEG files. This means that you can cut/join an MPEG file with standard file tools (like dd, cut), and it @@ -72,26 +73,26 @@ 2GB. There exists an extension allowing bigger files called OpenDMS. M$ currently strongly discourages its use and encourages ASF/WMV. Not that anybody cares.
-NOTE: DV cameras can create two types of AVI formats. One is common and +NOTE: DV cameras can create two types of AVI formats. One is common and playable, the other is neither.

There are two kinds of AVI files: +

There are two kinds of AVI files:

Interleaved: Audio and video content is interleaved. This is the +
Interleaved: Audio and video content is interleaved. This is the standard usage. Recommended and mostly used. Some tools create interleaved AVIs with bad sync. MPlayer detects these as interleaved, and this climaxes in loss of A/V sync, probably at seeking. These files should be played as non-interleaved (with the -ni option).
Non-interleaved: First comes the whole video stream, then the whole +
Non-interleaved: First comes the whole video stream, then the whole audio stream. It thus needs a lot of seeking, making playing from network or CD-Rom difficult.

MPlayer supports two kinds of timings for AVI files: +

MPlayer supports two kinds of timings for AVI files:

bps-based: It is based on the bitrate/samplerate of the video/audio stream. This - method is used by most players, including avifile and windows media player. + method is used by most players, including avifile + and windows media player. Files with broken headers, and files created with VBR audio but not VBR-compliant encoder will result in A/V desync with this method (mostly at seeking).

Any audio and video codec is allowed, but note that VBR audio is not well supported by most players. The file format makes it possible to use VBR @@ -116,25 +116,25 @@ media player and windows media encoder) and is very secret. v2.0 is published and patented :). Of course they differ, there is no compatibility at all (it is just another legal game). MPlayer supports only v1.0, as nobody has ever seen -v2.0 files :) . Note, that .ASF files nowdays come with the extension .WMA or +v2.0 files :). Note that ASF files nowadays come with the extension .WMA or .WMV.

2.1.1.4. QuickTime/MOV files

These are from the Macintosh. They usually have a .QT or .MOV extension. Note +

These formats were designed by Apple. They usually have a .QT or .MOV extension. Note that since the MPEG4 group chose QuickTime as the recommended file format -for MPEG4, their .MOV files come with a .MPG or .MP4 extension (Interestingly -the video and audio streams in these files are real .MPG and .AAC files. With the --dumpvideo/-dumpaudio options you can even extract them!).

+for MPEG4, their MOV files come with a .MPG or .MP4 extension (Interestingly +the video and audio streams in these files are real MPG and AAC files. With the +-dumpvideo and -dumpaudio options you can even extract them!).

Codecs: Any codec is allowed, both CBR and VBR. Note: most new QuickTime files use -Sorensen video and QDesign Music audio. These formats are completely -secret, and only Apple's QuickTime player is able to play these files (on -win/mac only).

+Sorensen video and QDesign Music audio. These formats have not been +disclosed and will probably remain so in the future, making Apple's QuickTime +player the only player able to play these files (on Windows/Mac OS only).

2.1.1.5. VIV files

2.1.1.5. VIVO files

MPlayer happily demuxes VIVO file formats. The biggest disadvantage of the format is that it has no index block, nor a fixed packet size or sync bytes @@ -144,8 +144,8 @@ of VIVO/2.0 files is a modified, nonstandard h.263v2. The audio is the same, it may be g.723 (standard), or Vivo Siren.

See the VIVO video codec -and VIVO audio codec sections for installation +

See the VIVO video codec +and VIVO audio codec sections for installation instructions.

@@ -169,7 +169,7 @@

2.1.1.8. NuppelVideo files

NuppelVideo -is a TV grabber tool (AFAIK:). MPlayer can read its .nuv +is a TV grabber tool (AFAIK:). MPlayer can read its .NUV files (only NuppelVideo 5.0). Those files can contain uncompressed YV12, YV12+RTJpeg compressed, YV12 RTJpeg+lzo compressed, and YV12+lzo compressed frames. MPlayer decodes (and also encodes them with MEncoder to