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
30 AOMedia Video 1 (AV1) decoder.
37 Select an operating point of a scalable AV1 bitstream (0 - 31). Default is 0.
45 This decoder decodes rawvideo streams.
50 @item top @var{top_field_first}
51 Specify the assumed field type of the input video.
54 the video is assumed to be progressive (default)
56 bottom-field-first is assumed
58 top-field-first is assumed
67 libdav1d allows libavcodec to decode the AOMedia Video 1 (AV1) codec.
68 Requires the presence of the libdav1d headers and library during configuration.
69 You need to explicitly configure the build with @code{--enable-libdav1d}.
73 The following options are supported by the libdav1d wrapper.
78 Set amount of frame threads to use during decoding. The default value is 0 (autodetect).
81 Set amount of tile threads to use during decoding. The default value is 0 (autodetect).
84 Apply film grain to the decoded video if present in the bitstream. Defaults to the
85 internal default of the library.
88 Select an operating point of a scalable AV1 bitstream (0 - 31). Defaults to the
89 internal default of the library.
92 Output all spatial layers of a scalable AV1 bitstream. The default value is false.
98 AVS2-P2/IEEE1857.4 video decoder wrapper.
100 This decoder allows libavcodec to decode AVS2 streams with davs2 library.
102 @c man end VIDEO DECODERS
106 AVS3-P2/IEEE1857.10 video decoder.
108 libuavs3d allows libavcodec to decode AVS3 streams.
109 Requires the presence of the libuavs3d headers and library during configuration.
110 You need to explicitly configure the build with @code{--enable-libuavs3d}.
114 The following option is supported by the libuavs3d wrapper.
119 Set amount of frame threads to use during decoding. The default value is 0 (autodetect).
123 @c man end VIDEO DECODERS
125 @chapter Audio Decoders
126 @c man begin AUDIO DECODERS
128 A description of some of the currently available audio decoders
135 This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
136 the undocumented RealAudio 3 (a.k.a. dnet).
138 @subsection AC-3 Decoder Options
142 @item -drc_scale @var{value}
143 Dynamic Range Scale Factor. The factor to apply to dynamic range values
144 from the AC-3 stream. This factor is applied exponentially. The default value is 1.
145 There are 3 notable scale factor ranges:
148 DRC disabled. Produces full range audio.
149 @item 0 < drc_scale <= 1
150 DRC enabled. Applies a fraction of the stream DRC value.
151 Audio reproduction is between full range and full compression.
153 DRC enabled. Applies drc_scale asymmetrically.
154 Loud sounds are fully compressed. Soft sounds are enhanced.
163 This decoder aims to implement the complete FLAC specification from Xiph.
165 @subsection FLAC Decoder options
170 The lavc FLAC encoder used to produce buggy streams with high lpc values
171 (like the default value). This option makes it possible to decode such streams
172 correctly by using lavc's old buggy lpc logic for decoding.
178 Internal wave synthesizer.
180 This decoder generates wave patterns according to predefined sequences. Its
181 use is purely internal and the format of the data it accepts is not publicly
186 libcelt decoder wrapper.
188 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
189 Requires the presence of the libcelt headers and library during configuration.
190 You need to explicitly configure the build with @code{--enable-libcelt}.
194 libgsm decoder wrapper.
196 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
197 the presence of the libgsm headers and library during configuration. You need
198 to explicitly configure the build with @code{--enable-libgsm}.
200 This decoder supports both the ordinary GSM and the Microsoft variant.
204 libilbc decoder wrapper.
206 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
207 audio codec. Requires the presence of the libilbc headers and library during
208 configuration. You need to explicitly configure the build with
209 @code{--enable-libilbc}.
213 The following option is supported by the libilbc wrapper.
218 Enable the enhancement of the decoded audio when set to 1. The default
219 value is 0 (disabled).
223 @section libopencore-amrnb
225 libopencore-amrnb decoder wrapper.
227 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
228 Narrowband audio codec. Using it requires the presence of the
229 libopencore-amrnb headers and library during configuration. You need to
230 explicitly configure the build with @code{--enable-libopencore-amrnb}.
232 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
233 without this library.
235 @section libopencore-amrwb
237 libopencore-amrwb decoder wrapper.
239 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
240 Wideband audio codec. Using it requires the presence of the
241 libopencore-amrwb headers and library during configuration. You need to
242 explicitly configure the build with @code{--enable-libopencore-amrwb}.
244 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
245 without this library.
249 libopus decoder wrapper.
251 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
252 Requires the presence of the libopus headers and library during
253 configuration. You need to explicitly configure the build with
254 @code{--enable-libopus}.
256 An FFmpeg native decoder for Opus exists, so users can decode Opus
257 without this library.
259 @c man end AUDIO DECODERS
261 @chapter Subtitles Decoders
262 @c man begin SUBTILES DECODERS
266 ARIB STD-B24 caption decoder.
268 Implements profiles A and C of the ARIB STD-B24 standard.
270 @subsection libaribb24 Decoder Options
274 @item -aribb24-base-path @var{path}
275 Sets the base path for the libaribb24 library. This is utilized for reading of
276 configuration files (for custom unicode conversions), and for dumping of
277 non-text symbols as images under that location.
281 @item -aribb24-skip-ruby-text @var{boolean}
282 Tells the decoder wrapper to skip text blocks that contain half-height ruby
297 Compute clut once if no matching CLUT is in the stream.
299 Compute clut if no matching CLUT is in the stream.
303 Always compute CLUT and override the one provided in the stream.
306 Selects the dvb substream, or all substreams if -1 which is default.
312 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
313 also be found in VobSub file pairs and in some Matroska files.
319 Specify the global palette used by the bitmaps. When stored in VobSub, the
320 palette is normally specified in the index file; in Matroska, the palette is
321 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
322 palette is stored in the IFO file, and therefore not available when reading
323 from dumped VOB files.
325 The format for this option is a string containing 16 24-bits hexadecimal
326 numbers (without 0x prefix) separated by commas, for example @code{0d00ee,
327 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
328 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
331 Specify the IFO file from which the global palette is obtained.
334 @item forced_subs_only
335 Only decode subtitle entries marked as forced. Some titles have forced
336 and non-forced subtitles in the same track. Setting this flag to @code{1}
337 will only keep the forced subtitles. Default value is @code{0}.
340 @section libzvbi-teletext
342 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
343 subtitles. Requires the presence of the libzvbi headers and library during
344 configuration. You need to explicitly configure the build with
345 @code{--enable-libzvbi}.
351 List of teletext page numbers to decode. Pages that do not match the specified
352 list are dropped. You may use the special @code{*} string to match all pages,
353 or @code{subtitle} to match all subtitle pages.
355 @item txt_default_region
356 Set default character set used for decoding, a value between 0 and 87 (see
357 ETS 300 706, Section 15, Table 32). Default value is -1, which does not
358 override the libzvbi default. This option is needed for some legacy level 1.0
359 transmissions which cannot signal the proper charset.
361 Discards the top teletext line. Default value is 1.
363 Specifies the format of the decoded subtitles.
366 The default format, you should use this for teletext pages, because certain
367 graphics and colors cannot be expressed in simple text or even ASS.
369 Simple text based output without formatting.
371 Formatted ASS output, subtitle pages and teletext pages are returned in
372 different styles, subtitle pages are stripped down to text, but an effort is
373 made to keep the text alignment and the formatting.
376 X offset of generated bitmaps, default is 0.
378 Y offset of generated bitmaps, default is 0.
379 @item txt_chop_spaces
380 Chops leading and trailing spaces and removes empty lines from the generated
381 text. This option is useful for teletext based subtitles where empty spaces may
382 be present at the start or at the end of the lines or empty lines may be
383 present between the subtitle lines because of double-sized teletext characters.
386 Sets the display duration of the decoded teletext pages or subtitles in
387 milliseconds. Default value is -1 which means infinity or until the next
388 subtitle event comes.
389 @item txt_transparent
390 Force transparent background of the generated teletext bitmaps. Default value
391 is 0 which means an opaque background.
393 Sets the opacity (0-255) of the teletext background. If
394 @option{txt_transparent} is not set, it only affects characters between a start
395 box and an end box, typically subtitles. Default value is 0 if
396 @option{txt_transparent} is set, 255 otherwise.
400 @c man end SUBTILES DECODERS