ffmpeg/doc/bitstream_filters.texi

   1 @chapter Bitstream Filters
   2 @c man begin BITSTREAM FILTERS
   3
   4 When you configure your FFmpeg build, all the supported bitstream
   5 filters are enabled by default. You can list all available ones using
   6 the configure option @code{--list-bsfs}.
   7
   8 You can disable all the bitstream filters using the configure option
   9 @code{--disable-bsfs}, and selectively enable any bitstream filter using
  10 the option @code{--enable-bsf=BSF}, or you can disable a particular
  11 bitstream filter using the option @code{--disable-bsf=BSF}.
  12
  13 The option @code{-bsfs} of the ff* tools will display the list of
  14 all the supported bitstream filters included in your build.
  15
  16 Below is a description of the currently available bitstream filters.
  17
  18 @section aac_adtstoasc
  19
  20 Convert MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration
  21 bitstream filter.
  22
  23 This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
  24 ADTS header and removes the ADTS header.
  25
  26 This is required for example when copying an AAC stream from a raw
  27 ADTS AAC container to a FLV or a MOV/MP4 file.
  28
  29 @section chomp
  30
  31 Remove zero padding at the end of a packet.
  32
  33 @section dump_extra
  34
  35 Add extradata to the beginning of the filtered packets.
  36
  37 The additional argument specifies which packets should be filtered.
  38 It accepts the values:
  39 @table @samp
  40 @item a
  41 add extradata to all key packets, but only if @var{local_header} is
  42 set in the @option{flags2} codec context field
  43
  44 @item k
  45 add extradata to all key packets
  46
  47 @item e
  48 add extradata to all packets
  49 @end table
  50
  51 If not specified it is assumed @samp{k}.
  52
  53 For example the following @command{ffmpeg} command forces a global
  54 header (thus disabling individual packet headers) in the H.264 packets
  55 generated by the @code{libx264} encoder, but corrects them by adding
  56 the header stored in extradata to the key packets:
  57 @example
  58 ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
  59 @end example
  60
  61 @section h264_mp4toannexb
  62
  63 Convert an H.264 bitstream from length prefixed mode to start code
  64 prefixed mode (as defined in the Annex B of the ITU-T H.264
  65 specification).
  66
  67 This is required by some streaming formats, typically the MPEG-2
  68 transport stream format ("mpegts").
  69
  70 For example to remux an MP4 file containing an H.264 stream to mpegts
  71 format with @command{ffmpeg}, you can use the command:
  72
  73 @example
  74 ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts
  75 @end example
  76
  77 @section imxdump
  78
  79 Modifies the bitstream to fit in MOV and to be usable by the Final Cut
  80 Pro decoder. This filter only applies to the mpeg2video codec, and is
  81 likely not needed for Final Cut Pro 7 and newer with the appropriate
  82 @option{-tag:v}.
  83
  84 For example, to remux 30 MB/sec NTSC IMX to MOV:
  85
  86 @example
  87 ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov
  88 @end example
  89
  90 @section mjpeg2jpeg
  91
  92 Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
  93
  94 MJPEG is a video codec wherein each video frame is essentially a
  95 JPEG image. The individual frames can be extracted without loss,
  96 e.g. by
  97
  98 @example
  99 ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
 100 @end example
 101
 102 Unfortunately, these chunks are incomplete JPEG images, because
 103 they lack the DHT segment required for decoding. Quoting from
 104 @url{http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml}:
 105
 106 Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
 107 commented that "MJPEG, or at least the MJPEG in AVIs having the
 108 MJPG fourcc, is restricted JPEG with a fixed -- and *omitted* --
 109 Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
 110 and it must use basic Huffman encoding, not arithmetic or
 111 progressive. . . . You can indeed extract the MJPEG frames and
 112 decode them with a regular JPEG decoder, but you have to prepend
 113 the DHT segment to them, or else the decoder won't have any idea
 114 how to decompress the data. The exact table necessary is given in
 115 the OpenDML spec."
 116
 117 This bitstream filter patches the header of frames extracted from an MJPEG
 118 stream (carrying the AVI1 header ID and lacking a DHT segment) to
 119 produce fully qualified JPEG images.
 120
 121 @example
 122 ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
 123 exiftran -i -9 frame*.jpg
 124 ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
 125 @end example
 126
 127 @section mjpega_dump_header
 128
 129 @section movsub
 130
 131 @section mp3_header_decompress
 132
 133 @section noise
 134
 135 Damages the contents of packets without damaging the container. Can be
 136 used for fuzzing or testing error resilience/concealment.
 137
 138 @example
 139 ffmpeg -i INPUT -c copy -bsf noise output.mkv
 140 @end example
 141
 142 @section remove_extra
 143
 144 @c man end BITSTREAM FILTERS