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.
88 Internal wave synthetizer.
90 This decoder generates wave patterns according to predefined sequences. Its
91 use is purely internal and the format of the data it accepts is not publicly
96 libcelt decoder wrapper.
98 libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec.
99 Requires the presence of the libcelt headers and library during configuration.
100 You need to explicitly configure the build with @code{--enable-libcelt}.
104 libgsm decoder wrapper.
106 libgsm allows libavcodec to decode the GSM full rate audio codec. Requires
107 the presence of the libgsm headers and library during configuration. You need
108 to explicitly configure the build with @code{--enable-libgsm}.
110 This decoder supports both the ordinary GSM and the Microsoft variant.
114 libilbc decoder wrapper.
116 libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC)
117 audio codec. Requires the presence of the libilbc headers and library during
118 configuration. You need to explicitly configure the build with
119 @code{--enable-libilbc}.
123 The following option is supported by the libilbc wrapper.
128 Enable the enhancement of the decoded audio when set to 1. The default
129 value is 0 (disabled).
133 @section libopencore-amrnb
135 libopencore-amrnb decoder wrapper.
137 libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate
138 Narrowband audio codec. Using it requires the presence of the
139 libopencore-amrnb headers and library during configuration. You need to
140 explicitly configure the build with @code{--enable-libopencore-amrnb}.
142 An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB
143 without this library.
145 @section libopencore-amrwb
147 libopencore-amrwb decoder wrapper.
149 libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate
150 Wideband audio codec. Using it requires the presence of the
151 libopencore-amrwb headers and library during configuration. You need to
152 explicitly configure the build with @code{--enable-libopencore-amrwb}.
154 An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB
155 without this library.
159 libopus decoder wrapper.
161 libopus allows libavcodec to decode the Opus Interactive Audio Codec.
162 Requires the presence of the libopus headers and library during
163 configuration. You need to explicitly configure the build with
164 @code{--enable-libopus}.
166 An FFmpeg native decoder for Opus exists, so users can decode Opus
167 without this library.
169 @c man end AUDIO DECODERS
171 @chapter Subtitles Decoders
172 @c man begin SUBTILES DECODERS
176 This codec decodes the bitmap subtitles used in DVDs; the same subtitles can
177 also be found in VobSub file pairs and in some Matroska files.
183 Specify the global palette used by the bitmaps. When stored in VobSub, the
184 palette is normally specified in the index file; in Matroska, the palette is
185 stored in the codec extra-data in the same format as in VobSub. In DVDs, the
186 palette is stored in the IFO file, and therefore not available when reading
187 from dumped VOB files.
189 The format for this option is a string containing 16 24-bits hexadecimal
190 numbers (without 0x prefix) separated by comas, for example @code{0d00ee,
191 ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1,
192 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}.
194 @item forced_subs_only
195 Only decode subtitle entries marked as forced. Some titles have forced
196 and non-forced subtitles in the same track. Setting this flag to @code{1}
197 will only keep the forced subtitles. Default value is @code{0}.
200 @section libzvbi-teletext
202 Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext
203 subtitles. Requires the presence of the libzvbi headers and library during
204 configuration. You need to explicitly configure the build with
205 @code{--enable-libzvbi}.
211 List of teletext page numbers to decode. You may use the special * string to
212 match all pages. Pages that do not match the specified list are dropped.
215 Discards the top teletext line. Default value is 1.
217 Specifies the format of the decoded subtitles. The teletext decoder is capable
218 of decoding the teletext pages to bitmaps or to simple text, you should use
219 "bitmap" for teletext pages, because certain graphics and colors cannot be
220 expressed in simple text. You might use "text" for teletext based subtitles if
221 your application can handle simple text based subtitles. Default value is
224 X offset of generated bitmaps, default is 0.
226 Y offset of generated bitmaps, default is 0.
227 @item txt_chop_spaces
228 Chops leading and trailing spaces and removes empty lines from the generated
229 text. This option is useful for teletext based subtitles where empty spaces may
230 be present at the start or at the end of the lines or empty lines may be
231 present between the subtitle lines because of double-sized teletext charactes.
234 Sets the display duration of the decoded teletext pages or subtitles in
235 miliseconds. Default value is 30000 which is 30 seconds.
236 @item txt_transparent
237 Force transparent background of the generated teletext bitmaps. Default value
238 is 0 which means an opaque (black) background.
241 @c man end SUBTILES DECODERS