eba453e03f
Partially addresses ticket #3198. Signed-off-by: Lou Logan <lou@lrcd.com> Tested-by: Dave Rice <dave@dericed.com>
145 lines
4.4 KiB
Plaintext
145 lines
4.4 KiB
Plaintext
@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.
|
|
|
|
Below is a description of the currently available bitstream filters.
|
|
|
|
@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 noise
|
|
|
|
Damages the contents of packets without damaging the container. Can be
|
|
used for fuzzing or testing error resilience/concealment.
|
|
|
|
@example
|
|
ffmpeg -i INPUT -c copy -bsf noise output.mkv
|
|
@end example
|
|
|
|
@section remove_extra
|
|
|
|
@c man end BITSTREAM FILTERS
|