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diff --git a/doc/decoders.texi b/doc/decoders.texi index 99d2008101..01fca9fc55 100644 --- a/doc/decoders.texi +++ b/doc/decoders.texi @@ -1,10 +1,10 @@ @chapter Decoders @c man begin DECODERS -Decoders are configured elements in Libav which allow the decoding of +Decoders are configured elements in FFmpeg which allow the decoding of multimedia streams. -When you configure your Libav build, all the supported native decoders +When you configure your FFmpeg build, all the supported native decoders are enabled by default. Decoders requiring an external library must be enabled manually via the corresponding @code{--enable-lib} option. You can list all available decoders using the configure option @code{--list-decoders}. @@ -14,11 +14,41 @@ You can disable all the decoders with the configure option with the options @code{--enable-decoder=@var{DECODER}} / @code{--disable-decoder=@var{DECODER}}. -The option @code{-decoders} of the av* tools will display the list of +The option @code{-decoders} of the ff* tools will display the list of enabled decoders. @c man end DECODERS +@chapter Video Decoders +@c man begin VIDEO DECODERS + +A description of some of the currently available video decoders +follows. + +@section rawvideo + +Raw video decoder. + +This decoder decodes rawvideo streams. + +@subsection Options + +@table @option +@item top @var{top_field_first} +Specify the assumed field type of the input video. +@table @option +@item -1 +the video is assumed to be progressive (default) +@item 0 +bottom-field-first is assumed +@item 1 +top-field-first is assumed +@end table + +@end table + +@c man end VIDEO DECODERS + @chapter Audio Decoders @c man begin AUDIO DECODERS @@ -53,4 +83,163 @@ Loud sounds are fully compressed. Soft sounds are enhanced. @end table +@section ffwavesynth + +Internal wave synthetizer. + +This decoder generates wave patterns according to predefined sequences. Its +use is purely internal and the format of the data it accepts is not publicly +documented. + +@section libcelt + +libcelt decoder wrapper. + +libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec. +Requires the presence of the libcelt headers and library during configuration. +You need to explicitly configure the build with @code{--enable-libcelt}. + +@section libgsm + +libgsm decoder wrapper. + +libgsm allows libavcodec to decode the GSM full rate audio codec. Requires +the presence of the libgsm headers and library during configuration. You need +to explicitly configure the build with @code{--enable-libgsm}. + +This decoder supports both the ordinary GSM and the Microsoft variant. + +@section libilbc + +libilbc decoder wrapper. + +libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC) +audio codec. Requires the presence of the libilbc headers and library during +configuration. You need to explicitly configure the build with +@code{--enable-libilbc}. + +@subsection Options + +The following option is supported by the libilbc wrapper. + +@table @option +@item enhance + +Enable the enhancement of the decoded audio when set to 1. The default +value is 0 (disabled). + +@end table + +@section libopencore-amrnb + +libopencore-amrnb decoder wrapper. + +libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate +Narrowband audio codec. Using it requires the presence of the +libopencore-amrnb headers and library during configuration. You need to +explicitly configure the build with @code{--enable-libopencore-amrnb}. + +An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB +without this library. + +@section libopencore-amrwb + +libopencore-amrwb decoder wrapper. + +libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate +Wideband audio codec. Using it requires the presence of the +libopencore-amrwb headers and library during configuration. You need to +explicitly configure the build with @code{--enable-libopencore-amrwb}. + +An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB +without this library. + +@section libopus + +libopus decoder wrapper. + +libopus allows libavcodec to decode the Opus Interactive Audio Codec. +Requires the presence of the libopus headers and library during +configuration. You need to explicitly configure the build with +@code{--enable-libopus}. + +An FFmpeg native decoder for Opus exists, so users can decode Opus +without this library. + @c man end AUDIO DECODERS + +@chapter Subtitles Decoders +@c man begin SUBTILES DECODERS + +@section dvdsub + +This codec decodes the bitmap subtitles used in DVDs; the same subtitles can +also be found in VobSub file pairs and in some Matroska files. + +@subsection Options + +@table @option +@item palette +Specify the global palette used by the bitmaps. When stored in VobSub, the +palette is normally specified in the index file; in Matroska, the palette is +stored in the codec extra-data in the same format as in VobSub. In DVDs, the +palette is stored in the IFO file, and therefore not available when reading +from dumped VOB files. + +The format for this option is a string containing 16 24-bits hexadecimal +numbers (without 0x prefix) separated by comas, for example @code{0d00ee, +ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, +7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}. + +@item ifo_palette +Specify the IFO file from which the global palette is obtained. +(experimental) + +@item forced_subs_only +Only decode subtitle entries marked as forced. Some titles have forced +and non-forced subtitles in the same track. Setting this flag to @code{1} +will only keep the forced subtitles. Default value is @code{0}. +@end table + +@section libzvbi-teletext + +Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext +subtitles. Requires the presence of the libzvbi headers and library during +configuration. You need to explicitly configure the build with +@code{--enable-libzvbi}. + +@subsection Options + +@table @option +@item txt_page +List of teletext page numbers to decode. You may use the special * string to +match all pages. Pages that do not match the specified list are dropped. +Default value is *. +@item txt_chop_top +Discards the top teletext line. Default value is 1. +@item txt_format +Specifies the format of the decoded subtitles. The teletext decoder is capable +of decoding the teletext pages to bitmaps or to simple text, you should use +"bitmap" for teletext pages, because certain graphics and colors cannot be +expressed in simple text. You might use "text" for teletext based subtitles if +your application can handle simple text based subtitles. Default value is +bitmap. +@item txt_left +X offset of generated bitmaps, default is 0. +@item txt_top +Y offset of generated bitmaps, default is 0. +@item txt_chop_spaces +Chops leading and trailing spaces and removes empty lines from the generated +text. This option is useful for teletext based subtitles where empty spaces may +be present at the start or at the end of the lines or empty lines may be +present between the subtitle lines because of double-sized teletext charactes. +Default value is 1. +@item txt_duration +Sets the display duration of the decoded teletext pages or subtitles in +miliseconds. Default value is 30000 which is 30 seconds. +@item txt_transparent +Force transparent background of the generated teletext bitmaps. Default value +is 0 which means an opaque (black) background. +@end table + +@c man end SUBTILES DECODERS |