4c592c3908
The format is now: -bsf:X filter1[=opt1=str1/opt2=str2],filter2 ie the parameters are appended after the filter name using '='. As ',' has been reserved already for the list of filters, '/' is just an example of token separation for now, but that could become part of the API to avoid each bsf using its own tokenization. The proper solution would be using AVOption, but this is overkill for now. Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
153 lines
4.7 KiB
Plaintext
153 lines
4.7 KiB
Plaintext
@chapter Bitstream Filters
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@c man begin BITSTREAM FILTERS
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When you configure your FFmpeg build, all the supported bitstream
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filters are enabled by default. You can list all available ones using
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the configure option @code{--list-bsfs}.
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You can disable all the bitstream filters using the configure option
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@code{--disable-bsfs}, and selectively enable any bitstream filter using
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the option @code{--enable-bsf=BSF}, or you can disable a particular
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bitstream filter using the option @code{--disable-bsf=BSF}.
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The option @code{-bsfs} of the ff* tools will display the list of
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all the supported bitstream filters included in your build.
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The ff* tools have a -bsf option applied per stream, taking a
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comma-separated list of filters, whose parameters follow the filter
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name after a '='.
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@example
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ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT
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@end example
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Below is a description of the currently available bitstream filters.
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@section aac_adtstoasc
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Convert MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration
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bitstream filter.
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This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
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ADTS header and removes the ADTS header.
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This is required for example when copying an AAC stream from a raw
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ADTS AAC container to a FLV or a MOV/MP4 file.
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@section chomp
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Remove zero padding at the end of a packet.
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@section dump_extra
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Add extradata to the beginning of the filtered packets.
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The additional argument specifies which packets should be filtered.
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It accepts the values:
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@table @samp
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@item a
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add extradata to all key packets, but only if @var{local_header} is
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set in the @option{flags2} codec context field
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@item k
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add extradata to all key packets
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@item e
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add extradata to all packets
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@end table
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If not specified it is assumed @samp{k}.
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For example the following @command{ffmpeg} command forces a global
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header (thus disabling individual packet headers) in the H.264 packets
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generated by the @code{libx264} encoder, but corrects them by adding
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the header stored in extradata to the key packets:
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@example
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ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
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@end example
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@section h264_mp4toannexb
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Convert an H.264 bitstream from length prefixed mode to start code
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prefixed mode (as defined in the Annex B of the ITU-T H.264
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specification).
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This is required by some streaming formats, typically the MPEG-2
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transport stream format ("mpegts").
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For example to remux an MP4 file containing an H.264 stream to mpegts
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format with @command{ffmpeg}, you can use the command:
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@example
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ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts
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@end example
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@section imxdump
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Modifies the bitstream to fit in MOV and to be usable by the Final Cut
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Pro decoder. This filter only applies to the mpeg2video codec, and is
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likely not needed for Final Cut Pro 7 and newer with the appropriate
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@option{-tag:v}.
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For example, to remux 30 MB/sec NTSC IMX to MOV:
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@example
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ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov
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@end example
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@section mjpeg2jpeg
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Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
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MJPEG is a video codec wherein each video frame is essentially a
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JPEG image. The individual frames can be extracted without loss,
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e.g. by
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@example
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ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
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@end example
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Unfortunately, these chunks are incomplete JPEG images, because
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they lack the DHT segment required for decoding. Quoting from
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@url{http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml}:
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Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
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commented that "MJPEG, or at least the MJPEG in AVIs having the
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MJPG fourcc, is restricted JPEG with a fixed -- and *omitted* --
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Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
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and it must use basic Huffman encoding, not arithmetic or
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progressive. . . . You can indeed extract the MJPEG frames and
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decode them with a regular JPEG decoder, but you have to prepend
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the DHT segment to them, or else the decoder won't have any idea
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how to decompress the data. The exact table necessary is given in
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the OpenDML spec."
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This bitstream filter patches the header of frames extracted from an MJPEG
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stream (carrying the AVI1 header ID and lacking a DHT segment) to
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produce fully qualified JPEG images.
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@example
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ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
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exiftran -i -9 frame*.jpg
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ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
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@end example
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@section mjpega_dump_header
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@section movsub
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@section mp3_header_decompress
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@section noise
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Damages the contents of packets without damaging the container. Can be
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used for fuzzing or testing error resilience/concealment.
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@example
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ffmpeg -i INPUT -c copy -bsf noise output.mkv
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@end example
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@section remove_extra
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@c man end BITSTREAM FILTERS
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