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
50 @c man end VIDEO DECODERS
52 @chapter Audio Decoders
53 @c man begin AUDIO DECODERS
55 A description of some of the currently available audio decoders
62 This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as
63 the undocumented RealAudio 3 (a.k.a. dnet).
65 @subsection AC-3 Decoder Options
69 @item -drc_scale @var{value}
70 Dynamic Range Scale Factor. The factor to apply to dynamic range values
71 from the AC-3 stream. This factor is applied exponentially.
72 There are 3 notable scale factor ranges:
75 DRC disabled. Produces full range audio.
76 @item 0 < drc_scale <= 1
77 DRC enabled. Applies a fraction of the stream DRC value.
78 Audio reproduction is between full range and full compression.
80 DRC enabled. Applies drc_scale asymmetrically.
81 Loud sounds are fully compressed. Soft sounds are enhanced.
90 This decoder aims to implement the complete FLAC specification from Xiph.
92 @subsection FLAC Decoder options
97 The lavc FLAC encoder used to produce buggy streams with high lpc values
98 (like the default value). This option makes it possible to decode such streams
99 correctly by using lavc's old buggy lpc logic for decoding.
105 Internal wave synthetizer.
107 This decoder generates wave patterns according to predefined sequences. Its
108 use is purely internal and the format of the data it accepts is not publicly
113 libcelt decoder wrapper.
115 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
116 Requires the presence of the libcelt headers and library during configuration.
117 You need to explicitly configure the build with @code{--enable-libcelt}.
121 libgsm decoder wrapper.
123 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
124 the presence of the libgsm headers and library during configuration. You need
125 to explicitly configure the build with @code{--enable-libgsm}.
127 This decoder supports both the ordinary GSM and the Microsoft variant.
131 libilbc decoder wrapper.
133 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
134 audio codec. Requires the presence of the libilbc headers and library during
135 configuration. You need to explicitly configure the build with
136 @code{--enable-libilbc}.
140 The following option is supported by the libilbc wrapper.
145 Enable the enhancement of the decoded audio when set to 1. The default
146 value is 0 (disabled).
150 @section libopencore-amrnb
152 libopencore-amrnb decoder wrapper.
154 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
155 Narrowband audio codec. Using it requires the presence of the
156 libopencore-amrnb headers and library during configuration. You need to
157 explicitly configure the build with @code{--enable-libopencore-amrnb}.
159 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
160 without this library.
162 @section libopencore-amrwb
164 libopencore-amrwb decoder wrapper.
166 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
167 Wideband audio codec. Using it requires the presence of the
168 libopencore-amrwb headers and library during configuration. You need to
169 explicitly configure the build with @code{--enable-libopencore-amrwb}.
171 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
172 without this library.
176 libopus decoder wrapper.
178 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
179 Requires the presence of the libopus headers and library during
180 configuration. You need to explicitly configure the build with
181 @code{--enable-libopus}.
183 An FFmpeg native decoder for Opus exists, so users can decode Opus
184 without this library.
186 @c man end AUDIO DECODERS
188 @chapter Subtitles Decoders
189 @c man begin SUBTILES DECODERS
193 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
194 also be found in VobSub file pairs and in some Matroska files.
200 Specify the global palette used by the bitmaps. When stored in VobSub, the
201 palette is normally specified in the index file; in Matroska, the palette is
202 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
203 palette is stored in the IFO file, and therefore not available when reading
204 from dumped VOB files.
206 The format for this option is a string containing 16 24-bits hexadecimal
207 numbers (without 0x prefix) separated by comas, for example @code{0d00ee,
208 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
209 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
212 Specify the IFO file from which the global palette is obtained.
215 @item forced_subs_only
216 Only decode subtitle entries marked as forced. Some titles have forced
217 and non-forced subtitles in the same track. Setting this flag to @code{1}
218 will only keep the forced subtitles. Default value is @code{0}.
221 @section libzvbi-teletext
223 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
224 subtitles. Requires the presence of the libzvbi headers and library during
225 configuration. You need to explicitly configure the build with
226 @code{--enable-libzvbi}.
232 List of teletext page numbers to decode. You may use the special * string to
233 match all pages. Pages that do not match the specified list are dropped.
236 Discards the top teletext line. Default value is 1.
238 Specifies the format of the decoded subtitles. The teletext decoder is capable
239 of decoding the teletext pages to bitmaps or to simple text, you should use
240 "bitmap" for teletext pages, because certain graphics and colors cannot be
241 expressed in simple text. You might use "text" for teletext based subtitles if
242 your application can handle simple text based subtitles. Default value is
245 X offset of generated bitmaps, default is 0.
247 Y offset of generated bitmaps, default is 0.
248 @item txt_chop_spaces
249 Chops leading and trailing spaces and removes empty lines from the generated
250 text. This option is useful for teletext based subtitles where empty spaces may
251 be present at the start or at the end of the lines or empty lines may be
252 present between the subtitle lines because of double-sized teletext charactes.
255 Sets the display duration of the decoded teletext pages or subtitles in
256 miliseconds. Default value is 30000 which is 30 seconds.
257 @item txt_transparent
258 Force transparent background of the generated teletext bitmaps. Default value
259 is 0 which means an opaque (black) background.
262 @c man end SUBTILES DECODERS