doc/bitstream_filters.texi
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 @chapter Bitstream Filters
 @c man begin BITSTREAM FILTERS
 
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 When you configure your FFmpeg build, all the supported bitstream
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 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.
 
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 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
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 ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1:opt2=str2][,filter2] OUTPUT
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 @end example
 
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 Below is a description of the currently available bitstream filters,
 with their parameters, if any.
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 @section aac_adtstoasc
 
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 Convert MPEG-2/4 AAC ADTS to an MPEG-4 Audio Specific Configuration
 bitstream.
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 This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
 ADTS header and removes the ADTS header.
 
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 This filter is required for example when copying an AAC stream from a
 raw ADTS AAC or an MPEG-TS container to MP4A-LATM, to an FLV file, or
 to MOV/MP4 files and related formats such as 3GP or M4A. Please note
 that it is auto-inserted for MP4A-LATM and MOV/MP4 and related formats.
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 @section chomp
 
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 Remove zero padding at the end of a packet.
 
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 @section dca_core
 
 Extract the core from a DCA/DTS stream, dropping extensions such as
 DTS-HD.
 
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 @section dump_extra
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 Add extradata to the beginning of the filtered packets.
 
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 @table @option
 @item freq
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 The additional argument specifies which packets should be filtered.
 It accepts the values:
 @table @samp
 @item k
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 @item keyframe
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 add extradata to all key packets
 
 @item e
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 @item all
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 add extradata to all packets
 @end table
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 @end table
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 If not specified it is assumed @samp{e}.
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 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
 
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 @section eac3_core
 
 Extract the core from a E-AC-3 stream, dropping extra channels.
 
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 @section extract_extradata
 
 Extract the in-band extradata.
 
 Certain codecs allow the long-term headers (e.g. MPEG-2 sequence headers,
 or H.264/HEVC (VPS/)SPS/PPS) to be transmitted either "in-band" (i.e. as a part
 of the bitstream containing the coded frames) or "out of band" (e.g. on the
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 container level). This latter form is called "extradata" in FFmpeg terminology.
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 This bitstream filter detects the in-band headers and makes them available as
 extradata.
 
 @table @option
 @item remove
 When this option is enabled, the long-term headers are removed from the
 bitstream after extraction.
 @end table
 
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 @section filter_units
 
 Remove units with types in or not in a given set from the stream.
 
 @table @option
 @item pass_types
 List of unit types or ranges of unit types to pass through while removing
 all others.  This is specified as a '|'-separated list of unit type values
 or ranges of values with '-'.
 
 @item remove_types
 Identical to @option{pass_types}, except the units in the given set
 removed and all others passed through.
 @end table
 
 Extradata is unchanged by this transformation, but note that if the stream
 contains inline parameter sets then the output may be unusable if they are
 removed.
 
 For example, to remove all non-VCL NAL units from an H.264 stream:
 @example
 ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=pass_types=1-5' OUTPUT
 @end example
 
 To remove all AUDs, SEI and filler from an H.265 stream:
 @example
 ffmpeg -i INPUT -c:v copy -bsf:v 'filter_units=remove_types=35|38-40' OUTPUT
 @end example
 
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 @section hapqa_extract
 
 Extract Rgb or Alpha part of an HAPQA file, without recompression, in order to create an HAPQ or an HAPAlphaOnly file.
 
 @table @option
 @item texture
 Specifies the texture to keep.
 
 @table @option
 @item color
 @item alpha
 @end table
 
 @end table
 
 Convert HAPQA to HAPQ
 @example
 ffmpeg -i hapqa_inputfile.mov -c copy -bsf:v hapqa_extract=texture=color -tag:v HapY -metadata:s:v:0 encoder="HAPQ" hapq_file.mov
 @end example
 
 Convert HAPQA to HAPAlphaOnly
 @example
 ffmpeg -i hapqa_inputfile.mov -c copy -bsf:v hapqa_extract=texture=alpha -tag:v HapA -metadata:s:v:0 encoder="HAPAlpha Only" hapalphaonly_file.mov
 @end example
 
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 @section h264_metadata
 
 Modify metadata embedded in an H.264 stream.
 
 @table @option
 @item aud
 Insert or remove AUD NAL units in all access units of the stream.
 
 @table @samp
 @item insert
 @item remove
 @end table
 
 @item sample_aspect_ratio
 Set the sample aspect ratio of the stream in the VUI parameters.
 
 @item video_format
 @item video_full_range_flag
 Set the video format in the stream (see H.264 section E.2.1 and
 table E-2).
 
 @item colour_primaries
 @item transfer_characteristics
 @item matrix_coefficients
 Set the colour description in the stream (see H.264 section E.2.1
 and tables E-3, E-4 and E-5).
 
 @item chroma_sample_loc_type
 Set the chroma sample location in the stream (see H.264 section
 E.2.1 and figure E-1).
 
 @item tick_rate
 Set the tick rate (num_units_in_tick / time_scale) in the VUI
 parameters.  This is the smallest time unit representable in the
 stream, and in many cases represents the field rate of the stream
 (double the frame rate).
 @item fixed_frame_rate_flag
 Set whether the stream has fixed framerate - typically this indicates
 that the framerate is exactly half the tick rate, but the exact
 meaning is dependent on interlacing and the picture structure (see
 H.264 section E.2.1 and table E-6).
 
 @item crop_left
 @item crop_right
 @item crop_top
 @item crop_bottom
 Set the frame cropping offsets in the SPS.  These values will replace
 the current ones if the stream is already cropped.
 
 These fields are set in pixels.  Note that some sizes may not be
 representable if the chroma is subsampled or the stream is interlaced
 (see H.264 section 7.4.2.1.1).
 
 @item sei_user_data
 Insert a string as SEI unregistered user data.  The argument must
 be of the form @emph{UUID+string}, where the UUID is as hex digits
 possibly separated by hyphens, and the string can be anything.
 
 For example, @samp{086f3693-b7b3-4f2c-9653-21492feee5b8+hello} will
 insert the string ``hello'' associated with the given UUID.
 
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 @item delete_filler
 Deletes both filler NAL units and filler SEI messages.
 
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 @end table
 
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 @section h264_mp4toannexb
 
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 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
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 transport stream format (muxer @code{mpegts}).
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 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
 
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 Please note that this filter is auto-inserted for MPEG-TS (muxer
 @code{mpegts}) and raw H.264 (muxer @code{h264}) output formats.
 
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 @section h264_redundant_pps
 
 This applies a specific fixup to some Blu-ray streams which contain
 redundant PPSs modifying irrelevant parameters of the stream which
 confuse other transformations which require correct extradata.
 
 A new single global PPS is created, and all of the redundant PPSs
 within the stream are removed.
 
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 @section hevc_metadata
 
 Modify metadata embedded in an HEVC stream.
 
 @table @option
 @item aud
 Insert or remove AUD NAL units in all access units of the stream.
 
 @table @samp
 @item insert
 @item remove
 @end table
 
 @item sample_aspect_ratio
 Set the sample aspect ratio in the stream in the VUI parameters.
 
 @item video_format
 @item video_full_range_flag
 Set the video format in the stream (see H.265 section E.3.1 and
 table E.2).
 
 @item colour_primaries
 @item transfer_characteristics
 @item matrix_coefficients
 Set the colour description in the stream (see H.265 section E.3.1
 and tables E.3, E.4 and E.5).
 
 @item chroma_sample_loc_type
 Set the chroma sample location in the stream (see H.265 section
 E.3.1 and figure E.1).
 
 @item tick_rate
 Set the tick rate in the VPS and VUI parameters (num_units_in_tick /
 time_scale).  Combined with @option{num_ticks_poc_diff_one}, this can
 set a constant framerate in the stream.  Note that it is likely to be
 overridden by container parameters when the stream is in a container.
 
 @item num_ticks_poc_diff_one
 Set poc_proportional_to_timing_flag in VPS and VUI and use this value
 to set num_ticks_poc_diff_one_minus1 (see H.265 sections 7.4.3.1 and
 E.3.1).  Ignored if @option{tick_rate} is not also set.
 
 @item crop_left
 @item crop_right
 @item crop_top
 @item crop_bottom
 Set the conformance window cropping offsets in the SPS.  These values
 will replace the current ones if the stream is already cropped.
 
 These fields are set in pixels.  Note that some sizes may not be
 representable if the chroma is subsampled (H.265 section 7.4.3.2.1).
 
 @end table
 
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 @section hevc_mp4toannexb
 
 Convert an HEVC/H.265 bitstream from length prefixed mode to start code
 prefixed mode (as defined in the Annex B of the ITU-T H.265
 specification).
 
 This is required by some streaming formats, typically the MPEG-2
 transport stream format (muxer @code{mpegts}).
 
 For example to remux an MP4 file containing an HEVC stream to mpegts
 format with @command{ffmpeg}, you can use the command:
 
 @example
 ffmpeg -i INPUT.mp4 -codec copy -bsf:v hevc_mp4toannexb OUTPUT.ts
 @end example
 
 Please note that this filter is auto-inserted for MPEG-TS (muxer
 @code{mpegts}) and raw HEVC/H.265 (muxer @code{h265} or
 @code{hevc}) output formats.
 
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 @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
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 @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
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 ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg
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 @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
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 ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
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 exiftran -i -9 frame*.jpg
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 ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
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 @end example
 
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 @section mjpegadump
 
 Add an MJPEG A header to the bitstream, to enable decoding by
 Quicktime.
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 @anchor{mov2textsub}
 @section mov2textsub
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 Extract a representable text file from MOV subtitles, stripping the
 metadata header from each subtitle packet.
 
 See also the @ref{text2movsub} filter.
 
 @section mp3decomp
 
 Decompress non-standard compressed MP3 audio headers.
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 @section mpeg2_metadata
 
 Modify metadata embedded in an MPEG-2 stream.
 
 @table @option
 @item display_aspect_ratio
 Set the display aspect ratio in the stream.
 
 The following fixed values are supported:
 @table @option
 @item 4/3
 @item 16/9
 @item 221/100
 @end table
 Any other value will result in square pixels being signalled instead
 (see H.262 section 6.3.3 and table 6-3).
 
 @item frame_rate
 Set the frame rate in the stream.  This is constructed from a table
 of known values combined with a small multiplier and divisor - if
 the supplied value is not exactly representable, the nearest
 representable value will be used instead (see H.262 section 6.3.3
 and table 6-4).
 
 @item video_format
 Set the video format in the stream (see H.262 section 6.3.6 and
 table 6-6).
 
 @item colour_primaries
 @item transfer_characteristics
 @item matrix_coefficients
 Set the colour description in the stream (see H.262 section 6.3.6
 and tables 6-7, 6-8 and 6-9).
 
 @end table
 
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 @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
 
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 @section noise
 
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 Damages the contents of packets or simply drops them without damaging the
 container. Can be used for fuzzing or testing error resilience/concealment.
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 Parameters:
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 @table @option
 @item amount
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 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.
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 @item dropamount
 A numeral string, whose value is related to how often packets will be dropped.
 Therefore, values below or equal to 0 are forbidden, and the lower the more
 frequent packets will be dropped, with 1 meaning every packet is dropped.
 @end table
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 The following example applies the modification to every byte but does not drop
 any packets.
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 @example
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 ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv
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 @end example
 
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 @section null
 This bitstream filter passes the packets through unchanged.
 
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 @section remove_extra
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 Remove extradata from packets.
 
 It accepts the following parameter:
 @table @option
 @item freq
 Set which frame types to remove extradata from.
 
 @table @samp
 @item k
 Remove extradata from non-keyframes only.
 
 @item keyframe
 Remove extradata from keyframes only.
 
 @item e, all
 Remove extradata from all frames.
 
 @end table
 @end table
 
 @anchor{text2movsub}
 @section text2movsub
 
 Convert text subtitles to MOV subtitles (as used by the @code{mov_text}
 codec) with metadata headers.
 
 See also the @ref{mov2textsub} filter.
 
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 @section trace_headers
 
 Log trace output containing all syntax elements in the coded stream
 headers (everything above the level of individual coded blocks).
 This can be useful for debugging low-level stream issues.
 
 Supports H.264, H.265 and MPEG-2.
 
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 @section vp9_superframe
 
 Merge VP9 invisible (alt-ref) frames back into VP9 superframes. This
 fixes merging of split/segmented VP9 streams where the alt-ref frame
 was split from its visible counterpart.
 
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 @section vp9_superframe_split
 
 Split VP9 superframes into single frames.
 
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 @section vp9_raw_reorder
 
 Given a VP9 stream with correct timestamps but possibly out of order,
 insert additional show-existing-frame packets to correct the ordering.
 
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 @c man end BITSTREAM FILTERS