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.
75 Select an operating point of a scalable AV1 bitstream (0 - 31). Defaults to the
76 internal default of the library.
79 Output all spatial layers of a scalable AV1 bitstream. The default value is false.
85 AVS2-P2/IEEE1857.4 video decoder wrapper.
87 This decoder allows libavcodec to decode AVS2 streams with davs2 library.
89 @c man end VIDEO DECODERS
93 AVS3-P2/IEEE1857.10 video decoder.
95 libuavs3d allows libavcodec to decode AVS3 streams.
96 Requires the presence of the libuavs3d headers and library during configuration.
97 You need to explicitly configure the build with @code{--enable-libuavs3d}.
101 The following option is supported by the libuavs3d wrapper.
106 Set amount of frame threads to use during decoding. The default value is 0 (autodetect).
110 @c man end VIDEO DECODERS
112 @chapter Audio Decoders
113 @c man begin AUDIO DECODERS
115 A description of some of the currently available audio decoders
122 This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
123 the undocumented RealAudio 3 (a.k.a. dnet).
125 @subsection AC-3 Decoder Options
129 @item -drc_scale @var{value}
130 Dynamic Range Scale Factor. The factor to apply to dynamic range values
131 from the AC-3 stream. This factor is applied exponentially. The default value is 1.
132 There are 3 notable scale factor ranges:
135 DRC disabled. Produces full range audio.
136 @item 0 < drc_scale <= 1
137 DRC enabled. Applies a fraction of the stream DRC value.
138 Audio reproduction is between full range and full compression.
140 DRC enabled. Applies drc_scale asymmetrically.
141 Loud sounds are fully compressed. Soft sounds are enhanced.
150 This decoder aims to implement the complete FLAC specification from Xiph.
152 @subsection FLAC Decoder options
157 The lavc FLAC encoder used to produce buggy streams with high lpc values
158 (like the default value). This option makes it possible to decode such streams
159 correctly by using lavc's old buggy lpc logic for decoding.
165 Internal wave synthesizer.
167 This decoder generates wave patterns according to predefined sequences. Its
168 use is purely internal and the format of the data it accepts is not publicly
173 libcelt decoder wrapper.
175 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
176 Requires the presence of the libcelt headers and library during configuration.
177 You need to explicitly configure the build with @code{--enable-libcelt}.
181 libgsm decoder wrapper.
183 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
184 the presence of the libgsm headers and library during configuration. You need
185 to explicitly configure the build with @code{--enable-libgsm}.
187 This decoder supports both the ordinary GSM and the Microsoft variant.
191 libilbc decoder wrapper.
193 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
194 audio codec. Requires the presence of the libilbc headers and library during
195 configuration. You need to explicitly configure the build with
196 @code{--enable-libilbc}.
200 The following option is supported by the libilbc wrapper.
205 Enable the enhancement of the decoded audio when set to 1. The default
206 value is 0 (disabled).
210 @section libopencore-amrnb
212 libopencore-amrnb decoder wrapper.
214 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
215 Narrowband audio codec. Using it requires the presence of the
216 libopencore-amrnb headers and library during configuration. You need to
217 explicitly configure the build with @code{--enable-libopencore-amrnb}.
219 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
220 without this library.
222 @section libopencore-amrwb
224 libopencore-amrwb decoder wrapper.
226 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
227 Wideband audio codec. Using it requires the presence of the
228 libopencore-amrwb headers and library during configuration. You need to
229 explicitly configure the build with @code{--enable-libopencore-amrwb}.
231 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
232 without this library.
236 libopus decoder wrapper.
238 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
239 Requires the presence of the libopus headers and library during
240 configuration. You need to explicitly configure the build with
241 @code{--enable-libopus}.
243 An FFmpeg native decoder for Opus exists, so users can decode Opus
244 without this library.
246 @c man end AUDIO DECODERS
248 @chapter Subtitles Decoders
249 @c man begin SUBTILES DECODERS
253 ARIB STD-B24 caption decoder.
255 Implements profiles A and C of the ARIB STD-B24 standard.
257 @subsection libaribb24 Decoder Options
261 @item -aribb24-base-path @var{path}
262 Sets the base path for the libaribb24 library. This is utilized for reading of
263 configuration files (for custom unicode conversions), and for dumping of
264 non-text symbols as images under that location.
268 @item -aribb24-skip-ruby-text @var{boolean}
269 Tells the decoder wrapper to skip text blocks that contain half-height ruby
284 Compute clut if no matching CLUT is in the stream.
288 Always compute CLUT and override the one provided in the stream.
291 Selects the dvb substream, or all substreams if -1 which is default.
297 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
298 also be found in VobSub file pairs and in some Matroska files.
304 Specify the global palette used by the bitmaps. When stored in VobSub, the
305 palette is normally specified in the index file; in Matroska, the palette is
306 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
307 palette is stored in the IFO file, and therefore not available when reading
308 from dumped VOB files.
310 The format for this option is a string containing 16 24-bits hexadecimal
311 numbers (without 0x prefix) separated by commas, for example @code{0d00ee,
312 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
313 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
316 Specify the IFO file from which the global palette is obtained.
319 @item forced_subs_only
320 Only decode subtitle entries marked as forced. Some titles have forced
321 and non-forced subtitles in the same track. Setting this flag to @code{1}
322 will only keep the forced subtitles. Default value is @code{0}.
325 @section libzvbi-teletext
327 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
328 subtitles. Requires the presence of the libzvbi headers and library during
329 configuration. You need to explicitly configure the build with
330 @code{--enable-libzvbi}.
336 List of teletext page numbers to decode. Pages that do not match the specified
337 list are dropped. You may use the special @code{*} string to match all pages,
338 or @code{subtitle} to match all subtitle pages.
340 @item txt_default_region
341 Set default character set used for decoding, a value between 0 and 87 (see
342 ETS 300 706, Section 15, Table 32). Default value is -1, which does not
343 override the libzvbi default. This option is needed for some legacy level 1.0
344 transmissions which cannot signal the proper charset.
346 Discards the top teletext line. Default value is 1.
348 Specifies the format of the decoded subtitles.
351 The default format, you should use this for teletext pages, because certain
352 graphics and colors cannot be expressed in simple text or even ASS.
354 Simple text based output without formatting.
356 Formatted ASS output, subtitle pages and teletext pages are returned in
357 different styles, subtitle pages are stripped down to text, but an effort is
358 made to keep the text alignment and the formatting.
361 X offset of generated bitmaps, default is 0.
363 Y offset of generated bitmaps, default is 0.
364 @item txt_chop_spaces
365 Chops leading and trailing spaces and removes empty lines from the generated
366 text. This option is useful for teletext based subtitles where empty spaces may
367 be present at the start or at the end of the lines or empty lines may be
368 present between the subtitle lines because of double-sized teletext characters.
371 Sets the display duration of the decoded teletext pages or subtitles in
372 milliseconds. Default value is -1 which means infinity or until the next
373 subtitle event comes.
374 @item txt_transparent
375 Force transparent background of the generated teletext bitmaps. Default value
376 is 0 which means an opaque background.
378 Sets the opacity (0-255) of the teletext background. If
379 @option{txt_transparent} is not set, it only affects characters between a start
380 box and an end box, typically subtitles. Default value is 0 if
381 @option{txt_transparent} is set, 255 otherwise.
385 @c man end SUBTILES DECODERS