[FFmpeg-devel] [PATCH] encoders.texi: update libvpx documentation

James Zern jzern at google.com
Thu Jun 11 05:58:33 CEST 2015

modeled after the libx264 section.
 doc/encoders.texi | 163 ++++++++++++++++++++++++++++++------------------------
 1 file changed, 92 insertions(+), 71 deletions(-)

diff --git a/doc/encoders.texi b/doc/encoders.texi
index 753e683..e0ad13e 100644
--- a/doc/encoders.texi
+++ b/doc/encoders.texi
@@ -1416,113 +1416,134 @@ You need to explicitly configure the build with @code{--enable-libvpx}.
 @subsection Options
-Mapping from FFmpeg to libvpx options with conversion notes in parentheses.
+The following options are supported by the libvpx wrapper. The
+ at command{vpxenc}-equivalent options or values are listed in parentheses
+for easy migration.
- at table @option
+To reduce the duplication of documentation, only the private options
+and some others requiring special attention are documented here. For
+the documentation of the undocumented generic options, see
+ at ref{codec-options,,the Codec Options chapter}.
- at item threads
+To get more documentation of the libvpx options, invoke the command
+ at command{ffmpeg -h encoder=libvpx}, @command{ffmpeg -h encoder=libvpx-vp9} or
+ at command{vpxenc --help}. Further information is available in the libvpx API
- at item profile
+ at table @option
- at item vb
+ at item b (@emph{target-bitrate})
+Set bitrate in bits/s. Note that FFmpeg's @option{b} option is
+expressed in bits/s, while @command{vpxenc}'s @option{target-bitrate} is in
- at item g
+ at item g (@emph{kf-max-dist})
- at item keyint_min
+ at item keyint_min (@emph{kf-min-dist})
- at item qmin
+ at item qmin (@emph{min-q})
- at item qmax
+ at item qmax (@emph{max-q})
- at item bufsize, vb
- at code{(bufsize * 1000 / vb)}
+ at item bufsize (@emph{buf-sz}, @emph{buf-optimal-sz})
+Set ratecontrol buffer size (in bits). Note @command{vpxenc}'s options are
+specified in milliseconds, the libvpx wrapper converts this value as follows:
+ at code{buf-sz = bufsize * 1000 / bitrate},
+ at code{buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6}.
- at code{(bufsize * 1000 / vb * 5 / 6)}
+ at item rc_init_occupancy (@emph{buf-initial-sz})
+Set number of bits which should be loaded into the rc buffer before decoding
+starts. Note @command{vpxenc}'s option is specified in milliseconds, the libvpx
+wrapper converts this value as follows:
+ at code{rc_init_occupancy * 1000 / bitrate}.
- at item rc_init_occupancy, vb
- at code{(rc_init_occupancy * 1000 / vb)}
+ at item undershoot-pct
+Datarate undershoot (min) percentage of the target bitrate.
- at item rc_buffer_aggressivity
+ at item overshoot-pct
+Datarate overshoot (max) percentage of the target bitrate.
- at item skip_threshold
+ at item skip_threshold (@emph{drop-frame})
- at item qcomp
+ at item qcomp (@emph{bias-pct})
- at item maxrate, vb
- at code{(maxrate * 100 / vb)}
+ at item maxrate (@emph{maxsection-pct})
+GOP max bitrate in bits/s. Note @command{vpxenc}'s option is specified as a
+percentage of the target bitrate, the libvpx wrapper converts this value as
+follows: @code{(maxrate * 100 / bitrate)}.
- at item minrate, vb
- at code{(minrate * 100 / vb)}
+ at item minrate (@emph{minsection-pct})
+GOP min bitrate in bits/s. Note @command{vpxenc}'s option is specified as a
+percentage of the target bitrate, the libvpx wrapper converts this value as
+follows: @code{(minrate * 100 / bitrate)}.
- at item minrate, maxrate, vb
- at code{VPX_CBR}
- at code{(minrate == maxrate == vb)}
+ at item minrate, maxrate, b @emph{end-usage=cbr}
+ at code{(minrate == maxrate == bitrate)}.
- at item crf
- at code{VPX_CQ}, @code{VP8E_SET_CQ_LEVEL}
+ at item crf (@emph{end-usage=cq}, @emph{cq-level})
- at item quality
+ at item quality, deadline (@emph{deadline})
 @table @option
 @item @var{best}
+Use best quality deadline. Poorly named and quite slow, this option should be
+avoided as it may give worse quality output than good.
 @item @var{good}
+Use good quality deadline. This is a good trade-off between speed and quality
+when used with the @option{cpu-used} option.
 @item @var{realtime}
- at code{VPX_DL_REALTIME}
+Use realtime quality deadline.
 @end table
- at item speed
- at code{VP8E_SET_CPUUSED}
+ at item speed, cpu-used (@emph{cpu-used})
+Quality/Speed ratio modifier.
- at item nr
+ at item nr (@emph{noise-sensitivity})
- at item mb_threshold
+ at item static-thresh
+A change threshold on blocks below which they will be skipped by the encoder.
- at item slices
+ at item slices (@emph{token-parts})
+Note that FFmpeg's @option{slices} option gives the total number of partitions,
+while @command{vpxenc}'s @option{token-parts} is given as
+ at code{log2(partitions)}.
 @item max-intra-rate
+Maximum I-frame bitrate (pct) 0=unlimited.
 @item force_key_frames
 @item Alternate reference frame related
 @table @option
- at item vp8flags altref
- at item @var{arnr_max_frames}
- at item @var{arnr_type}
- at code{VP8E_SET_ARNR_TYPE}
- at item @var{arnr_strength}
- at item @var{rc_lookahead}
- at end table
- at item vp8flags error_resilient
- at item aq_mode
- at code{VP9E_SET_AQ_MODE}
+ at item auto-alt-ref
+Enable use of alternate reference frames (2-pass only).
+ at item arnr-max-frames
+altref noise reduction max frame count.
+ at item arnr-type
+altref noise reduction filter type: backward, forward, centered.
+ at item arnr-strength
+altref noise reduction filter strength.
+ at item rc-lookahead, lag-in-frames (@emph{lag-in-frames})
+Set number of frames to look ahead for frametype and ratecontrol.
+ at end table
+ at item error-resilient
+Enable error resiliency features.
+ at item VP9-specific options
+ at table @option
+ at item lossless
+Lossless mode.
+ at item tile-columns
+Number of tile columns to use, log2.
+ at item tile-rows
+Number of tile rows to use, log2.
+ at item frame-parallel
+Enable frame parallel decodability features.
+ at item aq-mode
+Adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3:
+cyclic refresh).
+ at end table
 @end table

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