encoders.texi: update libvpx documentation

modeled after the libx264 section. Reviewed-by: Lou Logan <lou@lrcd.com> Reviewed-by: Stefano Sabatini <stefasab@gmail.com> Signed-off-by: James Zern <jzern@google.com>
10 years ago · 8ce321f0aa
--- a/doc/encoders.texi
+++ b/doc/encoders.texi
@@ -1416,113 +1416,141 @@ 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
@command{vpxenc}-equivalent options or values are listed in parentheses
 for easy migration.

@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
@ref{codec-options,,the Codec Options chapter}.

@item threads
 g_threads
 To get more documentation of the libvpx options, invoke the command
@command{ffmpeg -h encoder=libvpx}, @command{ffmpeg -h encoder=libvpx-vp9} or
@command{vpxenc --help}. Further information is available in the libvpx API
 documentation.

@item profile
 g_profile
@table @option

@item vb
 rc_target_bitrate
@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
 kilobits/s.

@item g
 kf_max_dist
@item g (@emph{kf-max-dist})

@item keyint_min
 kf_min_dist
@item keyint_min (@emph{kf-min-dist})

@item qmin
 rc_min_quantizer
@item qmin (@emph{min-q})

@item qmax
 rc_max_quantizer
@item qmax (@emph{max-q})

@item bufsize, vb
 rc_buf_sz
@code{(bufsize * 1000 / vb)}
@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:
@code{buf-sz = bufsize * 1000 / bitrate},
@code{buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6}.

 rc_buf_optimal_sz
@code{(bufsize * 1000 / vb * 5 / 6)}
@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:
@code{rc_init_occupancy * 1000 / bitrate}.

@item rc_init_occupancy, vb
 rc_buf_initial_sz
@code{(rc_init_occupancy * 1000 / vb)}
@item undershoot-pct
 Set datarate undershoot (min) percentage of the target bitrate.

@item rc_buffer_aggressivity
 rc_undershoot_pct
@item overshoot-pct
 Set datarate overshoot (max) percentage of the target bitrate.

@item skip_threshold
 rc_dropframe_thresh
@item skip_threshold (@emph{drop-frame})

@item qcomp
 rc_2pass_vbr_bias_pct
@item qcomp (@emph{bias-pct})

@item maxrate, vb
 rc_2pass_vbr_maxsection_pct
@code{(maxrate * 100 / vb)}
@item maxrate (@emph{maxsection-pct})
 Set 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)}.

@item minrate, vb
 rc_2pass_vbr_minsection_pct
@code{(minrate * 100 / vb)}
@item minrate (@emph{minsection-pct})
 Set 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)}.

@item minrate, maxrate, vb
@code{VPX_CBR}
@code{(minrate == maxrate == vb)}
@item minrate, maxrate, b @emph{end-usage=cbr}
@code{(minrate == maxrate == bitrate)}.

@item crf
@code{VPX_CQ}, @code{VP8E_SET_CQ_LEVEL}
@item crf (@emph{end-usage=cq}, @emph{cq-level})

@item quality
@table @option
@item @var{best}
@code{VPX_DL_BEST_QUALITY}
@item @var{good}
@code{VPX_DL_GOOD_QUALITY}
@item @var{realtime}
@code{VPX_DL_REALTIME}
@item quality, deadline (@emph{deadline})
@table @samp
@item 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 good
 Use good quality deadline. This is a good trade-off between speed and quality
 when used with the @option{cpu-used} option.
@item realtime
 Use realtime quality deadline.
@end table

@item speed
@code{VP8E_SET_CPUUSED}
@item speed, cpu-used (@emph{cpu-used})
 Set quality/speed ratio modifier. Higher values speed up the encode at the cost
 of quality.

@item nr
@code{VP8E_SET_NOISE_SENSITIVITY}
@item nr (@emph{noise-sensitivity})

@item mb_threshold
@code{VP8E_SET_STATIC_THRESHOLD}
@item static-thresh
 Set a change threshold on blocks below which they will be skipped by the
 encoder.

@item slices
@code{VP8E_SET_TOKEN_PARTITIONS}
@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
@code{log2(partitions)}.

@item max-intra-rate
@code{VP8E_SET_MAX_INTRA_BITRATE_PCT}
 Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0
 means unlimited.

@item force_key_frames
@code{VPX_EFLAG_FORCE_KF}

@item Alternate reference frame related
@table @option
@item vp8flags altref
@code{VP8E_SET_ENABLEAUTOALTREF}
@item @var{arnr_max_frames}
@code{VP8E_SET_ARNR_MAXFRAMES}
@item @var{arnr_type}
@code{VP8E_SET_ARNR_TYPE}
@item @var{arnr_strength}
@code{VP8E_SET_ARNR_STRENGTH}
@item @var{rc_lookahead}
 g_lag_in_frames
@end table

@item vp8flags error_resilient
 g_error_resilient

@item aq_mode
@code{VP9E_SET_AQ_MODE}
@item auto-alt-ref
 Enable use of alternate reference frames (2-pass only).
@item arnr-max-frames
 Set altref noise reduction max frame count.
@item arnr-type
 Set altref noise reduction filter type: backward, forward, centered.
@item arnr-strength
 Set altref noise reduction filter strength.
@item rc-lookahead, lag-in-frames (@emph{lag-in-frames})
 Set number of frames to look ahead for frametype and ratecontrol.
@end table

@item error-resilient
 Enable error resiliency features.

@item VP9-specific options
@table @option
@item lossless
 Enable lossless mode.
@item tile-columns
 Set number of tile columns to use. Note this is given as
@code{log2(tile_columns)}. For example, 8 tile columns would be requested by
 setting the @option{tile-columns} option to 3.
@item tile-rows
 Set number of tile rows to use. Note this is given as @code{log2(tile_rows)}.
 For example, 4 tile rows would be requested by setting the @option{tile-rows}
 option to 2.
@item frame-parallel
 Enable frame parallel decodability features.
@item aq-mode
 Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3:
 cyclic refresh).
@end table

@end table