diff options
Diffstat (limited to 'DOCS/formats.html')
| -rw-r--r-- | DOCS/formats.html | 93 |
1 files changed, 73 insertions, 20 deletions
diff --git a/DOCS/formats.html b/DOCS/formats.html index 045edb0d9c..d1e2fa6bed 100644 --- a/DOCS/formats.html +++ b/DOCS/formats.html @@ -29,7 +29,7 @@ faces, then tell them to RTFM.</P> <P>You see, a <B>codec</B> isn't equal to a <B>file format</B>.<BR> Video <B>codecs</B> are: MPEG1, MPEG2, DivX, Indeo5, 3ivx.<BR> -Video <B>formats</B> are: MPG, VOB, AVI, ASF.<BR> +Video <B>formats</B> are: MPG, AVI, ASF.<BR> </P> <P>In theory, you can happily put an OpenDivX video and MP3 audio @@ -45,25 +45,30 @@ create these files.</P> <P><B><A NAME=2.1.1>2.1.1. Video formats</A></B></P> -<P><B><A NAME=2.1.1.1>2.1.1.1. MPG, VOB, DAT files</A></B></P> +<P><B><A NAME=2.1.1.1>2.1.1.1. MPEG files</A></B></P> <P> <LI>MPG : this is the most <B>basic</B> form of MPEG file formats. Contains -MPEG1 video, and MP2 audio.</LI> -<LI>VOB : this is the MPEG file format on <B>DVD</B>s. Contains optionally -encoded MPEG2 video, and usually AC3 audio.<BR> -<B>Read the <A HREF="cd-dvd.html#4.2">DVD section</A> !</B></LI> -<LI>DAT : this is the MPEG file format on <B>Video CD</B>s. It's the same -as the MPG, but due to the nature VCDs are created and Linux is designed, +MPEG1 video, and MP2 (MPEG-1 layer 2) audio, or rarely MP1.</LI> +<LI>DAT : this is the very same format as MPG, just different extension. Used +on <B>Video CD</B>s. Due to the nature VCDs are created and Linux is designed, the DAT files can't be played nor copied from VCDs. You have to use the <CODE>-vcd</CODE> option to play the VideoCD.</LI> +<LI>VOB : this is the MPEG file format on <B>DVD</B>s. The same as MPG, plus +capability to contain subtitles, or non-MPEG (AC3) audio. Contains encoded MPEG2 +video, and usually AC3 audio, but MP2 is allowed too.<BR> +<B>Read the <A HREF="cd-dvd.html#4.2">DVD section</A> !</B></LI> </P> +<P>In MPEG files, series of frames are grouped together, and are independent +from the other groups. What this means is you can cut/join an MPEG file with +standard file-tools (like dd, cut), and it remains completely functional.</P> + <P>One important feature for MPGs is that they have a field to describe the aspect ratio of the video stream within. For example SVCDs have 480x480 resolution video, and in the header that field is set to 4:3, so it's played at 640x480. AVI files don't have this field, so one has to -scale it during encoding.</P> +rescale it during encoding.</P> <P><B><A NAME=2.1.1.2>2.1.1.2. AVI files</A></B></P> @@ -78,26 +83,74 @@ anybody cares.<BR> <B>NOTE</B> : DV cameras can create two types of AVI format, one is the usual and playable, the other is neither.</P> +<P>There are two kinds of AVI files: +<UL> + <LI><B>Interleaved</B> : audio and video content is interleaved. This is the + standard usage. Recommended and mostly used. Some tools create interleaved + AVIs with bad sync. <B>MPlayer</B> 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 <CODE>-ni</CODE> option).</LI> + <LI><B>Non-interleaved</B> : bad. First come the whole video stream, then the whole + audio stream, thus needs a lot of seeking. It's very bad when playing from + network or CDROM.</LI> +</UL> +</P> + +<P>MPlayer supports 2 kind of timing for AVI files: +<UL> + <LI><B>bps-based</B> : it is based on bitrate/samplerate of video/audio stream. This + 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).</LI> + <LI><B>interleaving-based</B> : it doesn't use bitrate value of the header, instead + it uses the relative position of interleaved audio and video chunks. Makes + some badly encoded file with VBR audio playable.</LI> +</UL> +</P> + +<P>Any audio and video codec is allowed, but note that VBR audio isn't well +supported by most of the players. The file format makes it possible to use VBR +audio, but most players expect CBR audio, thus they fail with VBR. VBR is +unusual, and Microsoft's AVI specs only describe CBR audio. I also note, that +most AVI encoders/multiplexers create bad files if using VBR audio. only 2 +exception (known by me): NaNDub and <A HREF="encoding.html">MEncoder</A>.</P> + <P><B><A NAME=2.1.1.3>2.1.1.3. ASF/WMV files</A></B></P> -<P>ASF is a new very undocumented fileformat from M$, and WMV is its -successor. They are very commercial, and anyone who writes an opensource -parser for them, soon meets certain doom. While creating the parser, it -was obvious to see how bulky, shit, and unusable they are. Not if anybody -would expect something else from M$. +<P>ASF (active streaming format) comes from Microsoft. They developed two +variants of ASF, v1.0 and v2.0. v1.0 is used by their media tools (windows +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's +just another legal game). <B>MPlayer</B> supports only v1.0, as nobody has ever seen +v2.0 files :) . Note, that .ASF files nowdays come with the extension .WMA or +.WMV.</P> + +<P><B><A NAME=2.1.1.4>2.1.1.4. QuickTime/MOV files</A></B></P> -<P><B><A NAME=2.1.1.4>2.1.1.4. QT/MOV files</A></B></P> +<P>These are from Macintosh. Usually have extensions of .QT or .MOV . Note +that since the MPEG4 Group chose QuickTime as the recommended file format +for MPEG4, their .MOV files come with .MPG or .MP4 extension.</P> + +<P><B>Codecs</B>: any codecs allowed, both CBR and VBR. Note: most new mov files use +<B>Sorenson</B> 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).</P> -<P>They are Apple's formats. Not much to say, basically well designed, -multipurpose, streamable, many features etc. Kinda hard to find documentation, -but we think the parser is perfect. <P><B><A NAME=2.1.1.5>2.1.1.5. VIV files</A></B></P> -<P><B>MPlayer</B> happily demuxes VIVO file formats. This code is new, and -is possibly buggy, no seeking yet. See the <A HREF=codecs.html#2.2.1.4>VIVO video codec</A> +<P><B>MPlayer</B> happily demuxes VIVO file formats. The format's big +disadvantage is that it has no index block, nor fixed packetsize or sync bytes, +and most files lack even keyframes, so forget seeking!</P> + +<P>VIVO/1.0 files' video codec is standard <B>h.263</B> . The VIVO/2.0 files' +video codec is a modified, nonstandard <B>h.263</B> . Audio is the same, +it may be <B>g.723</B> (standard), or <B>Vivo Siren</B> .</P> + +<P>See the <A HREF=codecs.html#2.2.1.4>VIVO video codec</A> and <A HREF=codecs.html#2.2.2.3>VIVO audio codec</A> sections for installation instructions.</P> |