diff options
author | Stefano Sabatini <stefasab@gmail.com> | 2013-10-30 17:25:29 +0400 |
---|---|---|
committer | Stefano Sabatini <stefasab@gmail.com> | 2013-11-01 15:51:39 +0400 |
commit | 2acc525d786f0ee4b0a354858a5f146ce6580658 (patch) | |
tree | 9c7a53907868a04bf42b7f0f58498d3b5e9a5d0a /doc/encoders.texi | |
parent | d339e03fc3b889fe60cc1dd00cdd18cb68aaa2ab (diff) |
doc/encoders: add libfaac encoder documentation
Diffstat (limited to 'doc/encoders.texi')
-rw-r--r-- | doc/encoders.texi | 111 |
1 files changed, 109 insertions, 2 deletions
diff --git a/doc/encoders.texi b/doc/encoders.texi index 840d55e5ab..d8583a52e2 100644 --- a/doc/encoders.texi +++ b/doc/encoders.texi @@ -38,8 +38,8 @@ As this encoder is experimental, unexpected behavior may exist from time to time. For a more stable AAC encoder, see @ref{libvo-aacenc}. However, be warned that it has a worse quality reported by some users. -@c todo @ref{libfaac}, @ref{libaacplus} -See also @ref{libfdk-aac-enc,,the libfdk_aac section}. +@c todo @ref{libaacplus} +See also @ref{libfdk-aac-enc,,libfdk_aac} and @ref{libfaac}. @subsection Options @@ -494,6 +494,113 @@ Selected by Encoder (default) @end table +@anchor{libfaac} +@section libfaac + +libfaac AAC (Advanced Audio Coding) encoder wrapper. + +Requires the presence of the libfaac headers and library during +configuration. You need to explicitly configure the build with +@code{--enable-libfaac --enable-nonfree}. + +This encoder is considered to be of higher quality with respect to the +@ref{aacenc,,the native experimental FFmpeg AAC encoder}. + +For more information see the libfaac project at +@url{http://www.audiocoding.com/faac.html/}. + +@subsection Options + +The following shared FFmpeg codec options are recognized. + +The following options are supported by the libfaac wrapper. The +@command{faac}-equivalent of the options are listed in parentheses. + +@table @option +@item b (@emph{-b}) +Set bit rate in bits/s for ABR (Average Bit Rate) mode. If the bit rate +is not explicitly specified, it is automatically set to a suitable +value depending on the selected profile. @command{faac} bitrate is +expressed in kilobits/s. + +Note that libfaac does not support CBR (Constant Bit Rate) but only +ABR (Average Bit Rate). + +If VBR mode is enabled this option is ignored. + +@item ar (@emph{-R}) +Set audio sampling rate (in Hz). + +@item ac (@emph{-c}) +Set the number of audio channels. + +@item cutoff (@emph{-C}) +Set cutoff frequency. If not specified (or explicitly set to 0) it +will use a value automatically computed by the library. Default value +is 0. + +@item profile +Set audio profile. + +The following profiles are recognized: +@table @samp +@item aac_main +Main AAC (Main) + +@item aac_low +Low Complexity AAC (LC) + +@item aac_ssr +Scalable Sample Rate (SSR) + +@item aac_ltp +Long Term Prediction (LTP) +@end table + +If not specified it is set to @samp{aac_low}. + +@item flags +qscale +Set constant quality VBR (Variable Bit Rate) mode. + +@item global_quality +Set quality in VBR mode as an integer number of lambda units. + +Only relevant when VBR mode is enabled with @code{flags +qscale}. The +value is converted to QP units by dividing it by @code{FF_QP2LAMBDA}, +and used to set the quality value used by libfaac. A reasonable range +for the option value in QP units is [10-500], the higher the value the +higher the quality. + +@item q (@emph{-q}) +Enable VBR mode when set to a non-negative value, and set constant +quality value as a double floating point value in QP units. + +The value sets the quality value used by libfaac. A reasonable range +for the option value is [10-500], the higher the value the higher the +quality. + +This option is valid only using the @command{ffmpeg} command-line +tool. For library interface users, use @option{global_quality}. +@end table + +@subsection Examples + +@itemize +@item +Use @command{ffmpeg} to convert an audio file to ABR 128 kbps AAC in an M4A (MP4) +container: +@example +ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a +@end example + +@item +Use @command{ffmpeg} to convert an audio file to VBR AAC, using the +LTP AAC profile: +@example +ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a +@end example +@end itemize + @anchor{libfdk-aac-enc} @section libfdk_aac |