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 The ff* tools have a -bsf option applied per stream, taking a
  17 comma-separated list of filters, whose parameters follow the filter
  18 name after a '='.
  19
  20 @example
  21 ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT
  22 @end example
  23
  24 Below is a description of the currently available bitstream filters,
  25 with their parameters, if any.
  26
  27 @section aac_adtstoasc
  28
  29 Convert MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration
  30 bitstream filter.
  31
  32 This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
  33 ADTS header and removes the ADTS header.
  34
  35 This is required for example when copying an AAC stream from a raw
  36 ADTS AAC container to a FLV or a MOV/MP4 file.
  37
  38 @section chomp
  39
  40 Remove zero padding at the end of a packet.
  41
  42 @section dump_extra
  43
  44 Add extradata to the beginning of the filtered packets.
  45
  46 The additional argument specifies which packets should be filtered.
  47 It accepts the values:
  48 @table @samp
  49 @item a
  50 add extradata to all key packets, but only if @var{local_header} is
  51 set in the @option{flags2} codec context field
  52
  53 @item k
  54 add extradata to all key packets
  55
  56 @item e
  57 add extradata to all packets
  58 @end table
  59
  60 If not specified it is assumed @samp{k}.
  61
  62 For example the following @command{ffmpeg} command forces a global
  63 header (thus disabling individual packet headers) in the H.264 packets
  64 generated by the @code{libx264} encoder, but corrects them by adding
  65 the header stored in extradata to the key packets:
  66 @example
  67 ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts
  68 @end example
  69
  70 @section h264_mp4toannexb
  71
  72 Convert an H.264 bitstream from length prefixed mode to start code
  73 prefixed mode (as defined in the Annex B of the ITU-T H.264
  74 specification).
  75
  76 This is required by some streaming formats, typically the MPEG-2
  77 transport stream format ("mpegts").
  78
  79 For example to remux an MP4 file containing an H.264 stream to mpegts
  80 format with @command{ffmpeg}, you can use the command:
  81
  82 @example
  83 ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts
  84 @end example
  85
  86 @section imxdump
  87
  88 Modifies the bitstream to fit in MOV and to be usable by the Final Cut
  89 Pro decoder. This filter only applies to the mpeg2video codec, and is
  90 likely not needed for Final Cut Pro 7 and newer with the appropriate
  91 @option{-tag:v}.
  92
  93 For example, to remux 30 MB/sec NTSC IMX to MOV:
  94
  95 @example
  96 ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov
  97 @end example
  98
  99 @section mjpeg2jpeg
 100
 101 Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.
 102
 103 MJPEG is a video codec wherein each video frame is essentially a
 104 JPEG image. The individual frames can be extracted without loss,
 105 e.g. by
 106
 107 @example
 108 ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
 109 @end example
 110
 111 Unfortunately, these chunks are incomplete JPEG images, because
 112 they lack the DHT segment required for decoding. Quoting from
 113 @url{http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml}:
 114
 115 Avery Lee, writing in the rec.video.desktop newsgroup in 2001,
 116 commented that "MJPEG, or at least the MJPEG in AVIs having the
 117 MJPG fourcc, is restricted JPEG with a fixed -- and *omitted* --
 118 Huffman table. The JPEG must be YCbCr colorspace, it must be 4:2:2,
 119 and it must use basic Huffman encoding, not arithmetic or
 120 progressive. . . . You can indeed extract the MJPEG frames and
 121 decode them with a regular JPEG decoder, but you have to prepend
 122 the DHT segment to them, or else the decoder won't have any idea
 123 how to decompress the data. The exact table necessary is given in
 124 the OpenDML spec."
 125
 126 This bitstream filter patches the header of frames extracted from an MJPEG
 127 stream (carrying the AVI1 header ID and lacking a DHT segment) to
 128 produce fully qualified JPEG images.
 129
 130 @example
 131 ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
 132 exiftran -i -9 frame*.jpg
 133 ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
 134 @end example
 135
 136 @section mjpega_dump_header
 137
 138 @section movsub
 139
 140 @section mp3_header_decompress
 141
 142 @section noise
 143
 144 Damages the contents of packets without damaging the container. Can be
 145 used for fuzzing or testing error resilience/concealment.
 146
 147 Parameters:
 148 A numeral string, whose value is related to how often output bytes will
 149 be modified. Therefore, values below or equal to 0 are forbidden, and
 150 the lower the more frequent bytes will be modified, with 1 meaning
 151 every byte is modified.
 152
 153 @example
 154 ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv
 155 @end example
 156 applies the modification to every byte.
 157
 158 @section remove_extra
 159
 160 @c man end BITSTREAM FILTERS