From 561e05136f1cbe28a79af1940aa137f70281eef4 Mon Sep 17 00:00:00 2001 From: Timothy Gu Date: Fri, 5 Jul 2013 20:37:18 -0700 Subject: [PATCH] doc/encoders: add libopus encoder doc Signed-off-by: Stefano Sabatini --- doc/encoders.texi | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) diff --git a/doc/encoders.texi b/doc/encoders.texi index afe4952c36..fb475865f7 100644 --- a/doc/encoders.texi +++ b/doc/encoders.texi @@ -600,6 +600,79 @@ default value is 0 (disabled). @end table +@section libopus + +libopus Opus Interactive Audio Codec encoder wrapper. + +Requires the presence of the libopus headers and library during +configuration. You need to explicitly configure the build with +@code{--enable-libopus}. + +@subsection Option Mapping + +Most libopus options are modeled after the @command{opusenc} utility from +opus-tools. The following is an option mapping chart describing options +supported by the libopus wrapper, and their @command{opusenc}-equivalent +in parentheses. + +@table @option + +@item b (@emph{bitrate}) +Set the bit rate in bits/s. FFmpeg's @option{b} option is +expressed in bits/s, while @command{opusenc}'s @option{bitrate} in +kilobits/s. + +@item vbr (@emph{vbr}, @emph{hard-cbr}, and @emph{cvbr}) +Set VBR mode. The FFmpeg @option{vbr} option has the following +valid arguments, with the their @command{opusenc} equivalent options +in parentheses: + +@table @samp +@item off (@emph{hard-cbr}) +Use constant bit rate encoding. + +@item on (@emph{vbr}) +Use variable bit rate encoding (the default). + +@item constrained (@emph{cvbr}) +Use constrained variable bit rate encoding. +@end table + +@item compression_level (@emph{comp}) +Set encoding algorithm complexity. Valid options are integers in +the 0-10 range. 0 gives the fastest encodes but lower quality, while 10 +gives the highest quality but slowest encoding. The default is 10. + +@item frame_duration (@emph{framesize}) +Set maximum frame size, or duration of a frame in milliseconds. The +argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller +frame sizes achieve lower latency but less quality at a given bitrate. +Sizes greater than 20ms are only interesting at fairly low bitrates. +The default of FFmpeg is 10ms, but is 20ms in @command{opusenc}. + +@item packet_loss (@emph{expect-loss}) +Set expected packet loss percentage. The default is 0. + +@item application (N.A.) +Set intended application type. Valid options are listed below: + +@table @samp +@item voip +Favor improved speech intelligibility. +@item audio +Favor faithfulness to the input (the default). +@item lowdelay +Restrict to only the lowest delay modes. +@end table + +@item cutoff (N.A.) +Set cutoff bandwidth in Hz. The argument must be exactly one of the +following: 4000, 6000, 8000, 12000, or 20000, corresponding to +narrowband, mediumband, wideband, super wideband, and fullband +respectively. The default is 0 (cutoff disabled). + +@end table + @section libwavpack A wrapper providing WavPack encoding through libwavpack. -- 2.11.0