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
91 @chapter Audio Decoders
92 @c man begin AUDIO DECODERS
94 A description of some of the currently available audio decoders
101 This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
102 the undocumented RealAudio 3 (a.k.a. dnet).
104 @subsection AC-3 Decoder Options
108 @item -drc_scale @var{value}
109 Dynamic Range Scale Factor. The factor to apply to dynamic range values
110 from the AC-3 stream. This factor is applied exponentially.
111 There are 3 notable scale factor ranges:
114 DRC disabled. Produces full range audio.
115 @item 0 < drc_scale <= 1
116 DRC enabled. Applies a fraction of the stream DRC value.
117 Audio reproduction is between full range and full compression.
119 DRC enabled. Applies drc_scale asymmetrically.
120 Loud sounds are fully compressed. Soft sounds are enhanced.
129 This decoder aims to implement the complete FLAC specification from Xiph.
131 @subsection FLAC Decoder options
136 The lavc FLAC encoder used to produce buggy streams with high lpc values
137 (like the default value). This option makes it possible to decode such streams
138 correctly by using lavc's old buggy lpc logic for decoding.
144 Internal wave synthesizer.
146 This decoder generates wave patterns according to predefined sequences. Its
147 use is purely internal and the format of the data it accepts is not publicly
152 libcelt decoder wrapper.
154 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
155 Requires the presence of the libcelt headers and library during configuration.
156 You need to explicitly configure the build with @code{--enable-libcelt}.
160 libgsm decoder wrapper.
162 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
163 the presence of the libgsm headers and library during configuration. You need
164 to explicitly configure the build with @code{--enable-libgsm}.
166 This decoder supports both the ordinary GSM and the Microsoft variant.
170 libilbc decoder wrapper.
172 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
173 audio codec. Requires the presence of the libilbc headers and library during
174 configuration. You need to explicitly configure the build with
175 @code{--enable-libilbc}.
179 The following option is supported by the libilbc wrapper.
184 Enable the enhancement of the decoded audio when set to 1. The default
185 value is 0 (disabled).
189 @section libopencore-amrnb
191 libopencore-amrnb decoder wrapper.
193 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
194 Narrowband audio codec. Using it requires the presence of the
195 libopencore-amrnb headers and library during configuration. You need to
196 explicitly configure the build with @code{--enable-libopencore-amrnb}.
198 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
199 without this library.
201 @section libopencore-amrwb
203 libopencore-amrwb decoder wrapper.
205 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
206 Wideband audio codec. Using it requires the presence of the
207 libopencore-amrwb headers and library during configuration. You need to
208 explicitly configure the build with @code{--enable-libopencore-amrwb}.
210 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
211 without this library.
215 libopus decoder wrapper.
217 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
218 Requires the presence of the libopus headers and library during
219 configuration. You need to explicitly configure the build with
220 @code{--enable-libopus}.
222 An FFmpeg native decoder for Opus exists, so users can decode Opus
223 without this library.
225 @c man end AUDIO DECODERS
227 @chapter Subtitles Decoders
228 @c man begin SUBTILES DECODERS
232 ARIB STD-B24 caption decoder.
234 Implements profiles A and C of the ARIB STD-B24 standard.
236 @subsection libaribb24 Decoder Options
240 @item -aribb24-base-path @var{path}
241 Sets the base path for the libaribb24 library. This is utilized for reading of
242 configuration files (for custom unicode conversions), and for dumping of
243 non-text symbols as images under that location.
247 @item -aribb24-skip-ruby-text @var{boolean}
248 Tells the decoder wrapper to skip text blocks that contain half-height ruby
263 Compute clut if no matching CLUT is in the stream.
267 Always compute CLUT and override the one provided in the stream.
270 Selects the dvb substream, or all substreams if -1 which is default.
276 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
277 also be found in VobSub file pairs and in some Matroska files.
283 Specify the global palette used by the bitmaps. When stored in VobSub, the
284 palette is normally specified in the index file; in Matroska, the palette is
285 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
286 palette is stored in the IFO file, and therefore not available when reading
287 from dumped VOB files.
289 The format for this option is a string containing 16 24-bits hexadecimal
290 numbers (without 0x prefix) separated by commas, for example @code{0d00ee,
291 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
292 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
295 Specify the IFO file from which the global palette is obtained.
298 @item forced_subs_only
299 Only decode subtitle entries marked as forced. Some titles have forced
300 and non-forced subtitles in the same track. Setting this flag to @code{1}
301 will only keep the forced subtitles. Default value is @code{0}.
304 @section libzvbi-teletext
306 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
307 subtitles. Requires the presence of the libzvbi headers and library during
308 configuration. You need to explicitly configure the build with
309 @code{--enable-libzvbi}.
315 List of teletext page numbers to decode. Pages that do not match the specified
316 list are dropped. You may use the special @code{*} string to match all pages,
317 or @code{subtitle} to match all subtitle pages.
319 @item txt_default_region
320 Set default G0 character set used for decoding, a value between 0 and 80 (see
321 ETS 300 706, Section 15, Table 32). Default value is -1, which does not
322 override the libzvbi default. This option is needed for some legacy level 1.0
323 transmissions which cannot signal the proper charset.
325 Discards the top teletext line. Default value is 1.
327 Specifies the format of the decoded subtitles.
330 The default format, you should use this for teletext pages, because certain
331 graphics and colors cannot be expressed in simple text or even ASS.
333 Simple text based output without formatting.
335 Formatted ASS output, subtitle pages and teletext pages are returned in
336 different styles, subtitle pages are stripped down to text, but an effort is
337 made to keep the text alignment and the formatting.
340 X offset of generated bitmaps, default is 0.
342 Y offset of generated bitmaps, default is 0.
343 @item txt_chop_spaces
344 Chops leading and trailing spaces and removes empty lines from the generated
345 text. This option is useful for teletext based subtitles where empty spaces may
346 be present at the start or at the end of the lines or empty lines may be
347 present between the subtitle lines because of double-sized teletext characters.
350 Sets the display duration of the decoded teletext pages or subtitles in
351 milliseconds. Default value is -1 which means infinity or until the next
352 subtitle event comes.
353 @item txt_transparent
354 Force transparent background of the generated teletext bitmaps. Default value
355 is 0 which means an opaque background.
357 Sets the opacity (0-255) of the teletext background. If
358 @option{txt_transparent} is not set, it only affects characters between a start
359 box and an end box, typically subtitles. Default value is 0 if
360 @option{txt_transparent} is set, 255 otherwise.
364 @c man end SUBTILES DECODERS