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Diffstat (limited to 'doc/bitstream_filters.texi')
| -rw-r--r-- | doc/bitstream_filters.texi | 105 |
1 files changed, 94 insertions, 11 deletions
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi index 6e7f8781ee..6431ce85f2 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}. @@ -10,20 +10,91 @@ 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 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 -@section dump_extradata +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 -@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 ("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 @@ -34,7 +105,7 @@ 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 @@ -57,21 +128,33 @@ 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 movsub -@section mp3_header_compress - @section mp3_header_decompress @section noise -@section remove_extradata +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 |