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Diffstat (limited to 'doc/bitstream_filters.texi')
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1 files changed, 192 insertions, 14 deletions
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi index 49b8a645d0..d394a12db1 100644 --- a/doc/bitstream_filters.texi +++ b/doc/bitstream_filters.texi @@ -1,7 +1,7 @@ @chapter Bitstream Filters @c man begin BITSTREAM FILTERS -When you configure your Libav build, all the supported bitstream +When you configure your FFmpeg build, all the supported bitstream filters are enabled by default. You can list all available ones using the configure option @code{--list-bsfs}. @@ -10,16 +10,69 @@ You can disable all the bitstream filters using the configure option the option @code{--enable-bsf=BSF}, or you can disable a particular bitstream filter using the option @code{--disable-bsf=BSF}. -The option @code{-bsfs} of the av* tools will display the list of +The option @code{-bsfs} of the ff* tools will display the list of all the supported bitstream filters included in your build. -Below is a description of the currently available bitstream filters. +The ff* tools have a -bsf option applied per stream, taking a +comma-separated list of filters, whose parameters follow the filter +name after a '='. + +@example +ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1:opt2=str2][,filter2] OUTPUT +@end example + +Below is a description of the currently available bitstream filters, +with their parameters, if any. @section aac_adtstoasc +Convert MPEG-2/4 AAC ADTS to an MPEG-4 Audio Specific Configuration +bitstream. + +This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4 +ADTS header and removes the ADTS header. + +This filter is required for example when copying an AAC stream from a +raw ADTS AAC or an MPEG-TS container to MP4A-LATM, to an FLV file, or +to MOV/MP4 files and related formats such as 3GP or M4A. Please note +that it is auto-inserted for MP4A-LATM and MOV/MP4 and related formats. + @section chomp -@section dump_extradata +Remove zero padding at the end of a packet. + +@section dca_core + +Extract the core from a DCA/DTS stream, dropping extensions such as +DTS-HD. + +@section dump_extra + +Add extradata to the beginning of the filtered packets. + +The additional argument specifies which packets should be filtered. +It accepts the values: +@table @samp +@item a +add extradata to all key packets, but only if @var{local_header} is +set in the @option{flags2} codec context field + +@item k +add extradata to all key packets + +@item e +add extradata to all packets +@end table + +If not specified it is assumed @samp{k}. + +For example the following @command{ffmpeg} command forces a global +header (thus disabling individual packet headers) in the H.264 packets +generated by the @code{libx264} encoder, but corrects them by adding +the header stored in extradata to the key packets: +@example +ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts +@end example @section extract_extradata @@ -28,7 +81,7 @@ Extract the in-band extradata. Certain codecs allow the long-term headers (e.g. MPEG-2 sequence headers, or H.264/HEVC (VPS/)SPS/PPS) to be transmitted either "in-band" (i.e. as a part of the bitstream containing the coded frames) or "out of band" (e.g. on the -container level). This latter form is called "extradata" in Libav terminology. +container level). This latter form is called "extradata" in FFmpeg terminology. This bitstream filter detects the in-band headers and makes them available as extradata. @@ -41,7 +94,55 @@ bitstream after extraction. @section h264_mp4toannexb -@section imx_dump_header +Convert an H.264 bitstream from length prefixed mode to start code +prefixed mode (as defined in the Annex B of the ITU-T H.264 +specification). + +This is required by some streaming formats, typically the MPEG-2 +transport stream format (muxer @code{mpegts}). + +For example to remux an MP4 file containing an H.264 stream to mpegts +format with @command{ffmpeg}, you can use the command: + +@example +ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts +@end example + +Please note that this filter is auto-inserted for MPEG-TS (muxer +@code{mpegts}) and raw H.264 (muxer @code{h264}) output formats. + +@section hevc_mp4toannexb + +Convert an HEVC/H.265 bitstream from length prefixed mode to start code +prefixed mode (as defined in the Annex B of the ITU-T H.265 +specification). + +This is required by some streaming formats, typically the MPEG-2 +transport stream format (muxer @code{mpegts}). + +For example to remux an MP4 file containing an HEVC stream to mpegts +format with @command{ffmpeg}, you can use the command: + +@example +ffmpeg -i INPUT.mp4 -codec copy -bsf:v hevc_mp4toannexb OUTPUT.ts +@end example + +Please note that this filter is auto-inserted for MPEG-TS (muxer +@code{mpegts}) and raw HEVC/H.265 (muxer @code{h265} or +@code{hevc}) output formats. + +@section imxdump + +Modifies the bitstream to fit in MOV and to be usable by the Final Cut +Pro decoder. This filter only applies to the mpeg2video codec, and is +likely not needed for Final Cut Pro 7 and newer with the appropriate +@option{-tag:v}. + +For example, to remux 30 MB/sec NTSC IMX to MOV: + +@example +ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov +@end example @section mjpeg2jpeg @@ -52,7 +153,7 @@ JPEG image. The individual frames can be extracted without loss, e.g. by @example -avconv -i ../some_mjpeg.avi -c:v copy frames_%d.jpg +ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg @end example Unfortunately, these chunks are incomplete JPEG images, because @@ -75,25 +176,102 @@ stream (carrying the AVI1 header ID and lacking a DHT segment) to produce fully qualified JPEG images. @example -avconv -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg +ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg exiftran -i -9 frame*.jpg -avconv -i frame_%d.jpg -c:v copy rotated.avi +ffmpeg -i frame_%d.jpg -c:v copy rotated.avi @end example -@section mjpega_dump_header +@section mjpegadump + +Add an MJPEG A header to the bitstream, to enable decoding by +Quicktime. + +@anchor{mov2textsub} +@section mov2textsub + +Extract a representable text file from MOV subtitles, stripping the +metadata header from each subtitle packet. + +See also the @ref{text2movsub} filter. -@section movsub +@section mp3decomp -@section mp3_header_compress +Decompress non-standard compressed MP3 audio headers. -@section mp3_header_decompress +@section mpeg4_unpack_bframes + +Unpack DivX-style packed B-frames. + +DivX-style packed B-frames are not valid MPEG-4 and were only a +workaround for the broken Video for Windows subsystem. +They use more space, can cause minor AV sync issues, require more +CPU power to decode (unless the player has some decoded picture queue +to compensate the 2,0,2,0 frame per packet style) and cause +trouble if copied into a standard container like mp4 or mpeg-ps/ts, +because MPEG-4 decoders may not be able to decode them, since they are +not valid MPEG-4. + +For example to fix an AVI file containing an MPEG-4 stream with +DivX-style packed B-frames using @command{ffmpeg}, you can use the command: + +@example +ffmpeg -i INPUT.avi -codec copy -bsf:v mpeg4_unpack_bframes OUTPUT.avi +@end example @section noise +Damages the contents of packets without damaging the container. Can be +used for fuzzing or testing error resilience/concealment. + +Parameters: +A numeral string, whose value is related to how often output bytes will +be modified. Therefore, values below or equal to 0 are forbidden, and +the lower the more frequent bytes will be modified, with 1 meaning +every byte is modified. + +@example +ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv +@end example +applies the modification to every byte. + @section null This bitstream filter passes the packets through unchanged. -@section remove_extradata +@section remove_extra + +Remove extradata from packets. + +It accepts the following parameter: +@table @option +@item freq +Set which frame types to remove extradata from. + +@table @samp +@item k +Remove extradata from non-keyframes only. + +@item keyframe +Remove extradata from keyframes only. + +@item e, all +Remove extradata from all frames. + +@end table +@end table + +@anchor{text2movsub} +@section text2movsub + +Convert text subtitles to MOV subtitles (as used by the @code{mov_text} +codec) with metadata headers. + +See also the @ref{mov2textsub} filter. + +@section vp9_superframe + +Merge VP9 invisible (alt-ref) frames back into VP9 superframes. This +fixes merging of split/segmented VP9 streams where the alt-ref frame +was split from its visible counterpart. @section vp9_superframe_split |