@chapter Bitstream Filters
 @c man begin BITSTREAM FILTERS
 

 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}.
 
 You can disable all the bitstream filters using the configure option
 @code{--disable-bsfs}, and selectively enable any bitstream filter using
 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 ff* tools will display the list of
 all the supported bitstream filters included in your build.
 

 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 MPEG-4 Audio Specific Configuration
 bitstream filter.
 
 This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
 ADTS header and removes the ADTS header.
 
 This is required for example when copying an AAC stream from a raw
 ADTS AAC container to a FLV or a MOV/MP4 file.
 

 @section chomp
 

 Remove zero padding at the end of a packet.
 

 @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 h264_mp4toannexb
 

 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 ("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
 

 @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
 
 Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
 
 MJPEG is a video codec wherein each video frame is essentially a
 JPEG image. The individual frames can be extracted without loss,
 e.g. by
 
 @example

 ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg

 @end example
 
 Unfortunately, these chunks are incomplete JPEG images, because
 they lack the DHT segment required for decoding. Quoting from
 @url{http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml}:
 
 Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
 commented that "MJPEG, or at least the MJPEG in AVIs having the
 MJPG fourcc, is restricted JPEG with a fixed -- and *omitted* --
 Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
 and it must use basic Huffman encoding, not arithmetic or
 progressive. . . . You can indeed extract the MJPEG frames and
 decode them with a regular JPEG decoder, but you have to prepend
 the DHT segment to them, or else the decoder won't have any idea
 how to decompress the data. The exact table necessary is given in
 the OpenDML spec."
 
 This bitstream filter patches the header of frames extracted from an MJPEG
 stream (carrying the AVI1 header ID and lacking a DHT segment) to
 produce fully qualified JPEG images.
 
 @example

 ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg

 exiftran -i -9 frame*.jpg

 ffmpeg -i frame_%d.jpg -c:v copy rotated.avi

 @end example
 

 @section mjpega_dump_header
 
 @section movsub
 
 @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 remove_extra

 
 @c man end BITSTREAM FILTERS