doc: Drop DJGPP section, Libav now compiles out-of-the-box on FreeDOS.

[ffmpeg] / doc / encoders.texi

diff --git a/doc/encoders.texi b/doc/encoders.texi
index 59337e2abeb3625adbfb736f64c50347cf0b2b83..d507b66f51369e3651649d298bdbb0e9cf5df51c 100644 (file)
--- a/doc/encoders.texi
+++ b/doc/encoders.texi
@@ -17,11 +17,15 @@ with the options @code{--enable-encoder=@var{ENCODER}} /
 The option @code{-codecs} of the ff* tools will display the list of
 enabled encoders.
 
-A description of some of the currently available encoders follows.
+@c man end ENCODERS
+
+@chapter Audio Encoders
+@c man begin AUDIO ENCODERS
 
-@section Audio Encoders
+A description of some of the currently available audio encoders
+follows.
 
-@subsection ac3 and ac3_fixed
+@section ac3 and ac3_fixed
 
 AC-3 audio encoders.
 
@@ -36,7 +40,7 @@ quality audio for a given bitrate. The @var{ac3_fixed} encoder is not the
 default codec for any of the output formats, so it must be specified explicitly
 using the option @code{-acodec ac3_fixed} in order to use it.
 
-@subheading AC-3 Metadata
+@subsection AC-3 Metadata
 
 The AC-3 metadata options are used to set parameters that describe the audio,
 but in most cases do not affect the audio encoding itself. Some of the options
@@ -55,7 +59,7 @@ documents.
 @item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf,Dolby Digital Professional Encoding Guidelines}
 @end itemize
 
-@subsubheading Metadata Control Options
+@subsubsection Metadata Control Options
 
 @table @option
 
@@ -72,7 +76,7 @@ Metadata values can be changed before encoding each frame.
 
 @end table
 
-@subsubheading Downmix Levels
+@subsubsection Downmix Levels
 
 @table @option
 
@@ -106,7 +110,7 @@ Silence Surround Channel(s)
 
 @end table
 
-@subsubheading Audio Production Information
+@subsubsection Audio Production Information
 Audio Production Information is optional information describing the mixing
 environment.  Either none or both of the fields are written to the bitstream.
 
@@ -140,7 +144,7 @@ Small Room
 
 @end table
 
-@subsubheading Other Metadata Options
+@subsubsection Other Metadata Options
 
 @table @option
 
@@ -195,7 +199,7 @@ Original Source (default)
 
 @end table
 
-@subsubheading Extended Bitstream Information
+@subsection Extended Bitstream Information
 The extended bitstream options are part of the Alternate Bit Stream Syntax as
 specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts.
 If any one parameter in a group is specified, all values in that group will be
@@ -205,7 +209,7 @@ will use these values instead of the ones specified in the @code{center_mixlev}
 and @code{surround_mixlev} options if it supports the Alternate Bit Stream
 Syntax.
 
-@subsubheading Extended Bitstream Information - Part 1
+@subsubsection Extended Bitstream Information - Part 1
 
 @table @option
 
@@ -302,7 +306,7 @@ Silence Surround Channel(s)
 
 @end table
 
-@subsubheading Extended Bitstream Information - Part 2
+@subsubsection Extended Bitstream Information - Part 2
 
 @table @option
 
@@ -353,4 +357,59 @@ HDCD A/D Converter
 
 @end table
 
-@c man end ENCODERS
+@subsection Other AC-3 Encoding Options
+
+@table @option
+
+@item -stereo_rematrixing @var{boolean}
+Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
+is an optional AC-3 feature that increases quality by selectively encoding
+the left/right channels as mid/side. This option is enabled by default, and it
+is highly recommended that it be left as enabled except for testing purposes.
+
+@end table
+
+@subheading Floating-Point-Only AC-3 Encoding Options
+
+These options are only valid for the floating-point encoder and do not exist
+for the fixed-point encoder due to the corresponding features not being
+implemented in fixed-point.
+
+@table @option
+
+@item -channel_coupling @var{boolean}
+Enables/Disables use of channel coupling, which is an optional AC-3 feature
+that increases quality by combining high frequency information from multiple
+channels into a single channel. The per-channel high frequency information is
+sent with less accuracy in both the frequency and time domains. This allows
+more bits to be used for lower frequencies while preserving enough information
+to reconstruct the high frequencies. This option is enabled by default for the
+floating-point encoder and should generally be left as enabled except for
+testing purposes or to increase encoding speed.
+@table @option
+@item -1
+@itemx auto
+Selected by Encoder (default)
+@item 0
+@itemx off
+Disable Channel Coupling
+@item 1
+@itemx on
+Enable Channel Coupling
+@end table
+
+@item -cpl_start_band @var{number}
+Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a
+value higher than the bandwidth is used, it will be reduced to 1 less than the
+coupling end band. If @var{auto} is used, the start band will be determined by
+the encoder based on the bit rate, sample rate, and channel layout. This option
+has no effect if channel coupling is disabled.
+@table @option
+@item -1
+@itemx auto
+Selected by Encoder (default)
+@end table
+
+@end table
+
+@c man end AUDIO ENCODERS