4 Decoders are configured elements in FFmpeg which allow the decoding of
7 When you configure your FFmpeg build, all the supported native decoders
8 are enabled by default. Decoders requiring an external library must be enabled
9 manually via the corresponding @code{--enable-lib} option. You can list all
10 available decoders using the configure option @code{--list-decoders}.
12 You can disable all the decoders with the configure option
13 @code{--disable-decoders} and selectively enable / disable single decoders
14 with the options @code{--enable-decoder=@var{DECODER}} /
15 @code{--disable-decoder=@var{DECODER}}.
17 The option @code{-decoders} of the ff* tools will display the list of
22 @chapter Video Decoders
23 @c man begin VIDEO DECODERS
25 A description of some of the currently available video decoders
32 This decoder decodes rawvideo streams.
37 @item top @var{top_field_first}
38 Specify the assumed field type of the input video.
41 the video is assumed to be progressive (default)
43 bottom-field-first is assumed
45 top-field-first is assumed
54 libdav1d allows libavcodec to decode the AOMedia Video 1 (AV1) codec.
55 Requires the presence of the libdav1d headers and library during configuration.
56 You need to explicitly configure the build with @code{--enable-libdav1d}.
60 The following options are supported by the libdav1d wrapper.
65 Set amount of frame threads to use during decoding. The default value is 0 (autodetect).
68 Set amount of tile threads to use during decoding. The default value is 0 (autodetect).
71 Apply film grain to the decoded video if present in the bitstream. Defaults to the
72 internal default of the library.
78 AVS2-P2/IEEE1857.4 video decoder wrapper.
80 This decoder allows libavcodec to decode AVS2 streams with davs2 library.
82 @c man end VIDEO DECODERS
84 @chapter Audio Decoders
85 @c man begin AUDIO DECODERS
87 A description of some of the currently available audio decoders
94 This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
95 the undocumented RealAudio 3 (a.k.a. dnet).
97 @subsection AC-3 Decoder Options
101 @item -drc_scale @var{value}
102 Dynamic Range Scale Factor. The factor to apply to dynamic range values
103 from the AC-3 stream. This factor is applied exponentially.
104 There are 3 notable scale factor ranges:
107 DRC disabled. Produces full range audio.
108 @item 0 < drc_scale <= 1
109 DRC enabled. Applies a fraction of the stream DRC value.
110 Audio reproduction is between full range and full compression.
112 DRC enabled. Applies drc_scale asymmetrically.
113 Loud sounds are fully compressed. Soft sounds are enhanced.
122 This decoder aims to implement the complete FLAC specification from Xiph.
124 @subsection FLAC Decoder options
129 The lavc FLAC encoder used to produce buggy streams with high lpc values
130 (like the default value). This option makes it possible to decode such streams
131 correctly by using lavc's old buggy lpc logic for decoding.
137 Internal wave synthesizer.
139 This decoder generates wave patterns according to predefined sequences. Its
140 use is purely internal and the format of the data it accepts is not publicly
145 libcelt decoder wrapper.
147 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
148 Requires the presence of the libcelt headers and library during configuration.
149 You need to explicitly configure the build with @code{--enable-libcelt}.
153 libgsm decoder wrapper.
155 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
156 the presence of the libgsm headers and library during configuration. You need
157 to explicitly configure the build with @code{--enable-libgsm}.
159 This decoder supports both the ordinary GSM and the Microsoft variant.
163 libilbc decoder wrapper.
165 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
166 audio codec. Requires the presence of the libilbc headers and library during
167 configuration. You need to explicitly configure the build with
168 @code{--enable-libilbc}.
172 The following option is supported by the libilbc wrapper.
177 Enable the enhancement of the decoded audio when set to 1. The default
178 value is 0 (disabled).
182 @section libopencore-amrnb
184 libopencore-amrnb decoder wrapper.
186 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
187 Narrowband audio codec. Using it requires the presence of the
188 libopencore-amrnb headers and library during configuration. You need to
189 explicitly configure the build with @code{--enable-libopencore-amrnb}.
191 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
192 without this library.
194 @section libopencore-amrwb
196 libopencore-amrwb decoder wrapper.
198 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
199 Wideband audio codec. Using it requires the presence of the
200 libopencore-amrwb headers and library during configuration. You need to
201 explicitly configure the build with @code{--enable-libopencore-amrwb}.
203 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
204 without this library.
208 libopus decoder wrapper.
210 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
211 Requires the presence of the libopus headers and library during
212 configuration. You need to explicitly configure the build with
213 @code{--enable-libopus}.
215 An FFmpeg native decoder for Opus exists, so users can decode Opus
216 without this library.
218 @c man end AUDIO DECODERS
220 @chapter Subtitles Decoders
221 @c man begin SUBTILES DECODERS
225 ARIB STD-B24 caption decoder.
227 Implements profiles A and C of the ARIB STD-B24 standard.
229 @subsection libaribb24 Decoder Options
233 @item -aribb24-base-path @var{path}
234 Sets the base path for the libaribb24 library. This is utilized for reading of
235 configuration files (for custom unicode conversions), and for dumping of
236 non-text symbols as images under that location.
240 @item -aribb24-skip-ruby-text @var{boolean}
241 Tells the decoder wrapper to skip text blocks that contain half-height ruby
256 Compute clut if no matching CLUT is in the stream.
260 Always compute CLUT and override the one provided in the stream.
263 Selects the dvb substream, or all substreams if -1 which is default.
269 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
270 also be found in VobSub file pairs and in some Matroska files.
276 Specify the global palette used by the bitmaps. When stored in VobSub, the
277 palette is normally specified in the index file; in Matroska, the palette is
278 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
279 palette is stored in the IFO file, and therefore not available when reading
280 from dumped VOB files.
282 The format for this option is a string containing 16 24-bits hexadecimal
283 numbers (without 0x prefix) separated by comas, for example @code{0d00ee,
284 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
285 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
288 Specify the IFO file from which the global palette is obtained.
291 @item forced_subs_only
292 Only decode subtitle entries marked as forced. Some titles have forced
293 and non-forced subtitles in the same track. Setting this flag to @code{1}
294 will only keep the forced subtitles. Default value is @code{0}.
297 @section libzvbi-teletext
299 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
300 subtitles. Requires the presence of the libzvbi headers and library during
301 configuration. You need to explicitly configure the build with
302 @code{--enable-libzvbi}.
308 List of teletext page numbers to decode. Pages that do not match the specified
309 list are dropped. You may use the special @code{*} string to match all pages,
310 or @code{subtitle} to match all subtitle pages.
313 Discards the top teletext line. Default value is 1.
315 Specifies the format of the decoded subtitles.
318 The default format, you should use this for teletext pages, because certain
319 graphics and colors cannot be expressed in simple text or even ASS.
321 Simple text based output without formatting.
323 Formatted ASS output, subtitle pages and teletext pages are returned in
324 different styles, subtitle pages are stripped down to text, but an effort is
325 made to keep the text alignment and the formatting.
328 X offset of generated bitmaps, default is 0.
330 Y offset of generated bitmaps, default is 0.
331 @item txt_chop_spaces
332 Chops leading and trailing spaces and removes empty lines from the generated
333 text. This option is useful for teletext based subtitles where empty spaces may
334 be present at the start or at the end of the lines or empty lines may be
335 present between the subtitle lines because of double-sized teletext characters.
338 Sets the display duration of the decoded teletext pages or subtitles in
339 milliseconds. Default value is -1 which means infinity or until the next
340 subtitle event comes.
341 @item txt_transparent
342 Force transparent background of the generated teletext bitmaps. Default value
343 is 0 which means an opaque background.
345 Sets the opacity (0-255) of the teletext background. If
346 @option{txt_transparent} is not set, it only affects characters between a start
347 box and an end box, typically subtitles. Default value is 0 if
348 @option{txt_transparent} is set, 255 otherwise.
352 @c man end SUBTILES DECODERS