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doc/encoders/libx264: review and extend option description

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Also, merge x264opts and x264-opts option docs to avoid duplication
and make it clearer that they provide mostly the same functionality.
This commit is contained in:
Stefano Sabatini 2023-08-26 01:10:09 +02:00
parent f84412d6f4
commit ddecc39c39
1 changed files with 36 additions and 29 deletions
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doc/encoders.texi
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@ -2421,6 +2421,10 @@ To get a more accurate and extensive documentation of the libx264
options, invoke the command @command{x264 --fullhelp} or consult
the libx264 documentation.
In the list below, note that the @command{x264} option name is shown
in parentheses after the libavcodec corresponding name, in case there
is a direct mapping.
@table @option
@item b (@emph{bitrate})
Set bitrate in bits/s. Note that FFmpeg's @option{b} option is
@ -2428,17 +2432,19 @@ expressed in bits/s, while @command{x264}'s @option{bitrate} is in
kilobits/s.
@item bf (@emph{bframes})
Number of B-frames between I and P-frames
@item g (@emph{keyint})
Maximum GOP size
@item qmin (@emph{qpmin})
Minimum quantizer scale.
Minimum quantizer scale
@item qmax (@emph{qpmax})
Maximum quantizer scale.
Maximum quantizer scale
@item qdiff (@emph{qpstep})
Maximum difference between quantizer scales.
Maximum difference between quantizer scales
@item qblur (@emph{qblur})
Quantizer curve blur
@ -2447,7 +2453,7 @@ Quantizer curve blur
Quantizer curve compression factor
@item refs (@emph{ref})
Number of reference frames each P-frame can use. The range is from @var{0-16}.
Number of reference frames each P-frame can use. The range is @var{0-16}.
@item level (@emph{level})
Set the @code{x264_param_t.i_level_idc} value in case the value is
@ -2469,7 +2475,8 @@ Sets the threshold for the scene change detection.
@item trellis (@emph{trellis})
Performs Trellis quantization to increase efficiency. Enabled by default.
@item nr (@emph{nr})
@item nr (@emph{nr})
Noise reduction
@item me_range (@emph{merange})
Maximum range of the motion search in pixels.
@ -2550,6 +2557,7 @@ open GOP by setting it to @code{-cgop}. The result is similar to
the behavior of @command{x264}'s @option{--open-gop} option.
@item rc_init_occupancy (@emph{vbv-init})
Initial VBV buffer occupancy
@item preset (@emph{preset})
Set the encoding preset.
@ -2595,7 +2603,7 @@ Set AQ strength, reduce blocking and blurring in flat and textured areas.
Use psychovisual optimizations when set to 1. When set to 0, it has the
same effect as @command{x264}'s @option{--no-psy} option.
@item psy-rd (@emph{psy-rd})
@item psy-rd (@emph{psy-rd})
Set strength of psychovisual optimization, in
@var{psy-rd}:@var{psy-trellis} format.
@ -2627,7 +2635,7 @@ to 1.
@item avcintra-class (@emph{class})
Configure the encoder to generate AVC-Intra.
Valid values are 50,100 and 200
Valid values are 50, 100 and 200
@item bluray-compat (@emph{bluray-compat})
Configure the encoder to be compatible with the bluray standard.
@ -2678,8 +2686,8 @@ Set loop filter parameters, in @var{alpha}:@var{beta} form.
Set fluctuations reduction in QP (before curve compression).
@item partitions (@emph{partitions})
Set partitions to consider as a comma-separated list of. Possible
values in the list:
Set partitions to consider as a comma-separated list of values.
Possible values in the list:
@table @samp
@item p8x8
@ -2735,19 +2743,32 @@ Variable bit rate.
Constant bit rate (not allowed in MP4 container).
@end table
@item x264opts (N.A.)
Set any x264 option, see @command{x264 --fullhelp} for a list.
@item x264opts @var{opts}
@item x264-params @var{opts}
Override the x264 configuration using a :-separated list of key=value
options.
Argument is a list of @var{key}=@var{value} couples separated by
":". In @var{filter} and @var{psy-rd} options that use ":" as a separator
themselves, use "," instead. They accept it as well since long ago but this
is kept undocumented for some reason.
The argument for both options is a list of @var{key}=@var{value}
couples separated by ":". With @option{x264opts} the value can be
omitted, and the value @code{1} is assumed in that case.
For @var{filter} and @var{psy-rd} options values that use ":" as a
separator themselves, use "," instead. They accept it as well since
long ago but this is kept undocumented for some reason.
For example, the options might be provided as:
@example
level=30:bframes=0:weightp=0:cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:no-fast-pskip=1:subq=6:8x8dct=0:trellis=0
@end example
For example to specify libx264 encoding options with @command{ffmpeg}:
@example
ffmpeg -i foo.mpg -c:v libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
@end example
To get the complete list of the libx264 options, invoke the command
@command{x264 --fullhelp} or consult the libx264 documentation.
@item a53cc @var{boolean}
Import closed captions (which must be ATSC compatible format) into output.
Only the mpeg2 and h264 decoders provide these. Default is 1 (on).
@ -2758,20 +2779,6 @@ Import user data unregistered SEI if available into output. Default is 0 (off).
@item mb_info @var{boolean}
Set mb_info data through AVFrameSideData, only useful when used from the
API. Default is 0 (off).
@item x264-params (N.A.)
Override the x264 configuration using a :-separated list of key=value
parameters.
This option is functionally the same as the @option{x264opts}, but is
duplicated for compatibility with the Libav fork.
For example to specify libx264 encoding options with @command{ffmpeg}:
@example
ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT
@end example
@end table
Encoding ffpresets for common usages are provided so they can be used with the