1151 lines
31 KiB
Plaintext
1151 lines
31 KiB
Plaintext
@chapter Encoders
|
|
@c man begin ENCODERS
|
|
|
|
Encoders are configured elements in FFmpeg which allow the encoding of
|
|
multimedia streams.
|
|
|
|
When you configure your FFmpeg build, all the supported native encoders
|
|
are enabled by default. Encoders requiring an external library must be enabled
|
|
manually via the corresponding @code{--enable-lib} option. You can list all
|
|
available encoders using the configure option @code{--list-encoders}.
|
|
|
|
You can disable all the encoders with the configure option
|
|
@code{--disable-encoders} and selectively enable / disable single encoders
|
|
with the options @code{--enable-encoder=@var{ENCODER}} /
|
|
@code{--disable-encoder=@var{ENCODER}}.
|
|
|
|
The option @code{-codecs} of the ff* tools will display the list of
|
|
enabled encoders.
|
|
|
|
@c man end ENCODERS
|
|
|
|
@chapter Audio Encoders
|
|
@c man begin AUDIO ENCODERS
|
|
|
|
A description of some of the currently available audio encoders
|
|
follows.
|
|
|
|
@section ac3 and ac3_fixed
|
|
|
|
AC-3 audio encoders.
|
|
|
|
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as
|
|
the undocumented RealAudio 3 (a.k.a. dnet).
|
|
|
|
The @var{ac3} encoder uses floating-point math, while the @var{ac3_fixed}
|
|
encoder only uses fixed-point integer math. This does not mean that one is
|
|
always faster, just that one or the other may be better suited to a
|
|
particular system. The floating-point encoder will generally produce better
|
|
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.
|
|
|
|
@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
|
|
do directly affect or influence the decoding and playback of the resulting
|
|
bitstream, while others are just for informational purposes. A few of the
|
|
options will add bits to the output stream that could otherwise be used for
|
|
audio data, and will thus affect the quality of the output. Those will be
|
|
indicated accordingly with a note in the option list below.
|
|
|
|
These parameters are described in detail in several publicly-available
|
|
documents.
|
|
@itemize
|
|
@item @uref{http://www.atsc.org/cms/standards/a_52-2010.pdf,A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard}
|
|
@item @uref{http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf,A/54 - Guide to the Use of the ATSC Digital Television Standard}
|
|
@item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf,Dolby Metadata Guide}
|
|
@item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf,Dolby Digital Professional Encoding Guidelines}
|
|
@end itemize
|
|
|
|
@subsubsection Metadata Control Options
|
|
|
|
@table @option
|
|
|
|
@item -per_frame_metadata @var{boolean}
|
|
Allow Per-Frame Metadata. Specifies if the encoder should check for changing
|
|
metadata for each frame.
|
|
@table @option
|
|
@item 0
|
|
The metadata values set at initialization will be used for every frame in the
|
|
stream. (default)
|
|
@item 1
|
|
Metadata values can be changed before encoding each frame.
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@subsubsection Downmix Levels
|
|
|
|
@table @option
|
|
|
|
@item -center_mixlev @var{level}
|
|
Center Mix Level. The amount of gain the decoder should apply to the center
|
|
channel when downmixing to stereo. This field will only be written to the
|
|
bitstream if a center channel is present. The value is specified as a scale
|
|
factor. There are 3 valid values:
|
|
@table @option
|
|
@item 0.707
|
|
Apply -3dB gain
|
|
@item 0.595
|
|
Apply -4.5dB gain (default)
|
|
@item 0.500
|
|
Apply -6dB gain
|
|
@end table
|
|
|
|
@item -surround_mixlev @var{level}
|
|
Surround Mix Level. The amount of gain the decoder should apply to the surround
|
|
channel(s) when downmixing to stereo. This field will only be written to the
|
|
bitstream if one or more surround channels are present. The value is specified
|
|
as a scale factor. There are 3 valid values:
|
|
@table @option
|
|
@item 0.707
|
|
Apply -3dB gain
|
|
@item 0.500
|
|
Apply -6dB gain (default)
|
|
@item 0.000
|
|
Silence Surround Channel(s)
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@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.
|
|
|
|
@table @option
|
|
|
|
@item -mixing_level @var{number}
|
|
Mixing Level. Specifies peak sound pressure level (SPL) in the production
|
|
environment when the mix was mastered. Valid values are 80 to 111, or -1 for
|
|
unknown or not indicated. The default value is -1, but that value cannot be
|
|
used if the Audio Production Information is written to the bitstream. Therefore,
|
|
if the @code{room_type} option is not the default value, the @code{mixing_level}
|
|
option must not be -1.
|
|
|
|
@item -room_type @var{type}
|
|
Room Type. Describes the equalization used during the final mixing session at
|
|
the studio or on the dubbing stage. A large room is a dubbing stage with the
|
|
industry standard X-curve equalization; a small room has flat equalization.
|
|
This field will not be written to the bitstream if both the @code{mixing_level}
|
|
option and the @code{room_type} option have the default values.
|
|
@table @option
|
|
@item 0
|
|
@itemx notindicated
|
|
Not Indicated (default)
|
|
@item 1
|
|
@itemx large
|
|
Large Room
|
|
@item 2
|
|
@itemx small
|
|
Small Room
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@subsubsection Other Metadata Options
|
|
|
|
@table @option
|
|
|
|
@item -copyright @var{boolean}
|
|
Copyright Indicator. Specifies whether a copyright exists for this audio.
|
|
@table @option
|
|
@item 0
|
|
@itemx off
|
|
No Copyright Exists (default)
|
|
@item 1
|
|
@itemx on
|
|
Copyright Exists
|
|
@end table
|
|
|
|
@item -dialnorm @var{value}
|
|
Dialogue Normalization. Indicates how far the average dialogue level of the
|
|
program is below digital 100% full scale (0 dBFS). This parameter determines a
|
|
level shift during audio reproduction that sets the average volume of the
|
|
dialogue to a preset level. The goal is to match volume level between program
|
|
sources. A value of -31dB will result in no volume level change, relative to
|
|
the source volume, during audio reproduction. Valid values are whole numbers in
|
|
the range -31 to -1, with -31 being the default.
|
|
|
|
@item -dsur_mode @var{mode}
|
|
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround
|
|
(Pro Logic). This field will only be written to the bitstream if the audio
|
|
stream is stereo. Using this option does @b{NOT} mean the encoder will actually
|
|
apply Dolby Surround processing.
|
|
@table @option
|
|
@item 0
|
|
@itemx notindicated
|
|
Not Indicated (default)
|
|
@item 1
|
|
@itemx off
|
|
Not Dolby Surround Encoded
|
|
@item 2
|
|
@itemx on
|
|
Dolby Surround Encoded
|
|
@end table
|
|
|
|
@item -original @var{boolean}
|
|
Original Bit Stream Indicator. Specifies whether this audio is from the
|
|
original source and not a copy.
|
|
@table @option
|
|
@item 0
|
|
@itemx off
|
|
Not Original Source
|
|
@item 1
|
|
@itemx on
|
|
Original Source (default)
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@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
|
|
written to the bitstream. Default values are used for those that are written
|
|
but have not been specified. If the mixing levels are written, the decoder
|
|
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.
|
|
|
|
@subsubsection Extended Bitstream Information - Part 1
|
|
|
|
@table @option
|
|
|
|
@item -dmix_mode @var{mode}
|
|
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt
|
|
(Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
|
|
@table @option
|
|
@item 0
|
|
@itemx notindicated
|
|
Not Indicated (default)
|
|
@item 1
|
|
@itemx ltrt
|
|
Lt/Rt Downmix Preferred
|
|
@item 2
|
|
@itemx loro
|
|
Lo/Ro Downmix Preferred
|
|
@end table
|
|
|
|
@item -ltrt_cmixlev @var{level}
|
|
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the
|
|
center channel when downmixing to stereo in Lt/Rt mode.
|
|
@table @option
|
|
@item 1.414
|
|
Apply +3dB gain
|
|
@item 1.189
|
|
Apply +1.5dB gain
|
|
@item 1.000
|
|
Apply 0dB gain
|
|
@item 0.841
|
|
Apply -1.5dB gain
|
|
@item 0.707
|
|
Apply -3.0dB gain
|
|
@item 0.595
|
|
Apply -4.5dB gain (default)
|
|
@item 0.500
|
|
Apply -6.0dB gain
|
|
@item 0.000
|
|
Silence Center Channel
|
|
@end table
|
|
|
|
@item -ltrt_surmixlev @var{level}
|
|
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the
|
|
surround channel(s) when downmixing to stereo in Lt/Rt mode.
|
|
@table @option
|
|
@item 0.841
|
|
Apply -1.5dB gain
|
|
@item 0.707
|
|
Apply -3.0dB gain
|
|
@item 0.595
|
|
Apply -4.5dB gain
|
|
@item 0.500
|
|
Apply -6.0dB gain (default)
|
|
@item 0.000
|
|
Silence Surround Channel(s)
|
|
@end table
|
|
|
|
@item -loro_cmixlev @var{level}
|
|
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the
|
|
center channel when downmixing to stereo in Lo/Ro mode.
|
|
@table @option
|
|
@item 1.414
|
|
Apply +3dB gain
|
|
@item 1.189
|
|
Apply +1.5dB gain
|
|
@item 1.000
|
|
Apply 0dB gain
|
|
@item 0.841
|
|
Apply -1.5dB gain
|
|
@item 0.707
|
|
Apply -3.0dB gain
|
|
@item 0.595
|
|
Apply -4.5dB gain (default)
|
|
@item 0.500
|
|
Apply -6.0dB gain
|
|
@item 0.000
|
|
Silence Center Channel
|
|
@end table
|
|
|
|
@item -loro_surmixlev @var{level}
|
|
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the
|
|
surround channel(s) when downmixing to stereo in Lo/Ro mode.
|
|
@table @option
|
|
@item 0.841
|
|
Apply -1.5dB gain
|
|
@item 0.707
|
|
Apply -3.0dB gain
|
|
@item 0.595
|
|
Apply -4.5dB gain
|
|
@item 0.500
|
|
Apply -6.0dB gain (default)
|
|
@item 0.000
|
|
Silence Surround Channel(s)
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@subsubsection Extended Bitstream Information - Part 2
|
|
|
|
@table @option
|
|
|
|
@item -dsurex_mode @var{mode}
|
|
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX
|
|
(7.1 matrixed to 5.1). Using this option does @b{NOT} mean the encoder will actually
|
|
apply Dolby Surround EX processing.
|
|
@table @option
|
|
@item 0
|
|
@itemx notindicated
|
|
Not Indicated (default)
|
|
@item 1
|
|
@itemx on
|
|
Dolby Surround EX Off
|
|
@item 2
|
|
@itemx off
|
|
Dolby Surround EX On
|
|
@end table
|
|
|
|
@item -dheadphone_mode @var{mode}
|
|
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone
|
|
encoding (multi-channel matrixed to 2.0 for use with headphones). Using this
|
|
option does @b{NOT} mean the encoder will actually apply Dolby Headphone
|
|
processing.
|
|
@table @option
|
|
@item 0
|
|
@itemx notindicated
|
|
Not Indicated (default)
|
|
@item 1
|
|
@itemx on
|
|
Dolby Headphone Off
|
|
@item 2
|
|
@itemx off
|
|
Dolby Headphone On
|
|
@end table
|
|
|
|
@item -ad_conv_type @var{type}
|
|
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
|
|
conversion.
|
|
@table @option
|
|
@item 0
|
|
@itemx standard
|
|
Standard A/D Converter (default)
|
|
@item 1
|
|
@itemx hdcd
|
|
HDCD A/D Converter
|
|
@end table
|
|
|
|
@end table
|
|
|
|
@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
|
|
|
|
@subsection 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
|
|
|
|
@section libmp3lame
|
|
|
|
LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper.
|
|
|
|
Requires the presence of the libmp3lame headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libmp3lame}.
|
|
|
|
@subsection Option Mapping
|
|
|
|
The following options are supported by the libmp3lame wrapper,
|
|
the LAME-equivalent options follow the FFmpeg ones.
|
|
|
|
@multitable @columnfractions .2 .2
|
|
@item FFmpeg @tab LAME
|
|
@item b @tab b
|
|
Set bitrate expressed in bits/s, LAME @code{bitrate} is expressed in
|
|
kilobits/s.
|
|
@item q @tab V
|
|
Set quality setting for VBR.
|
|
@item compression_level @tab q
|
|
Set algorithm quality. Valid arguments are integers in the 0-9 range.
|
|
@item reservoir @tab N.A.
|
|
Enable use of bit reservoir. LAME has this enabled by default.
|
|
@item joint_stereo @tab -m j
|
|
Enable the encoder to use (on a frame by frame basis) either L/R
|
|
stereo or mid/side stereo.
|
|
@end multitable
|
|
|
|
@section libopencore-amrnb
|
|
|
|
OpenCORE Adaptive Multi-Rate Narrowband encoder.
|
|
|
|
Requires the presence of the libopencore-amrnb headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libopencore-amrnb --enable-version3}.
|
|
|
|
This is a mono-only encoder. Officially it only supports 8000Hz sample rate,
|
|
but you can override it by setting @option{strict} to @samp{unofficial} or
|
|
lower.
|
|
|
|
@subsection Options
|
|
|
|
@table @option
|
|
|
|
@item b
|
|
Set bitrate in bits per second. Only the following bitrates are supported,
|
|
otherwise libavcodec will round to the nearest valid bitrate.
|
|
|
|
@table @option
|
|
@item 4750
|
|
@item 5150
|
|
@item 5900
|
|
@item 6700
|
|
@item 7400
|
|
@item 7950
|
|
@item 10200
|
|
@item 12200
|
|
@end table
|
|
|
|
@item dtx
|
|
Allow discontinuous transmission (generate comfort noise) when set to 1. The
|
|
default value is 0 (disabled).
|
|
|
|
@end table
|
|
|
|
@section libtwolame
|
|
|
|
TwoLAME MP2 encoder wrapper.
|
|
|
|
Requires the presence of the libtwolame headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libtwolame}.
|
|
|
|
@subsection Options Mapping
|
|
|
|
The following options are supported by the libtwolame wrapper. The
|
|
TwoLAME-equivalent options follow the FFmpeg ones and are in
|
|
parentheses.
|
|
|
|
@table @option
|
|
@item b
|
|
(b) Set bitrate in bits/s. Note that FFmpeg @code{b} option is
|
|
expressed in bits/s, twolame @code{b} in kilobits/s. The default
|
|
value is 128k.
|
|
|
|
@item q
|
|
(V) Set quality for experimental VBR support. Maximum value range is
|
|
from -50 to 50, useful range is from -10 to 10.
|
|
|
|
@item mode
|
|
(mode) Set MPEG mode. Possible values:
|
|
|
|
@table @samp
|
|
@item auto
|
|
Choose mode automatically based on the input. This is the default.
|
|
@item stereo
|
|
Stereo
|
|
@item joint_stereo
|
|
Joint stereo
|
|
@item dual_channel
|
|
Dual channel
|
|
@item mono
|
|
Mono
|
|
@end table
|
|
|
|
@item psymodel
|
|
(psyc-mode) Set psychoacoustic model to use in encoding. The argument
|
|
must be an integer between -1 and 4, inclusive. The higher the value,
|
|
the better the quality. The default value is 3.
|
|
|
|
@item energy_levels
|
|
(energy) Enable energy levels extensions when set to 1. The default
|
|
value is 0 (disabled).
|
|
|
|
@item error_protection
|
|
(protect) Enable CRC error protection when set to 1. The default value
|
|
is 0 (disabled).
|
|
|
|
@item copyright
|
|
(copyright) Set MPEG audio copyright flag when set to 1. The default
|
|
value is 0 (disabled).
|
|
|
|
@item original
|
|
(original) Set MPEG audio original flag when set to 1. The default
|
|
value is 0 (disabled).
|
|
|
|
@end table
|
|
|
|
@section libvo-aacenc
|
|
|
|
VisualOn AAC encoder.
|
|
|
|
Requires the presence of the libvo-aacenc headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libvo-aacenc --enable-version3}.
|
|
|
|
@subsection Options
|
|
|
|
The VisualOn AAC encoder only support encoding AAC-LC and up to 2
|
|
channels. It is also CBR-only. It is considered to be worse than the
|
|
native experimental FFmpeg AAC encoder.
|
|
|
|
@table @option
|
|
|
|
@item b
|
|
Bitrate.
|
|
|
|
@end table
|
|
|
|
@section libvo-amrwbenc
|
|
|
|
VisualOn Adaptive Multi-Rate Wideband encoder.
|
|
|
|
Requires the presence of the libvo-amrwbenc headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libvo-amrwbenc --enable-version3}.
|
|
|
|
This is a mono-only encoder. Officially it only supports 16000Hz sample
|
|
rate, but you can override it by setting @option{strict} to
|
|
@samp{unofficial} or lower.
|
|
|
|
@subsection Options
|
|
|
|
@table @option
|
|
|
|
@item b
|
|
Set bitrate in bits/s. Only the following bitrates are supported, otherwise
|
|
libavcodec will round to the nearest valid bitrate.
|
|
|
|
@table @samp
|
|
@item 6600
|
|
@item 8850
|
|
@item 12650
|
|
@item 14250
|
|
@item 15850
|
|
@item 18250
|
|
@item 19850
|
|
@item 23050
|
|
@item 23850
|
|
@end table
|
|
|
|
@item dtx
|
|
Allow discontinuous transmission (generate comfort noise) when set to 1. The
|
|
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.
|
|
|
|
Only lossless mode using 32-bit integer samples is supported currently.
|
|
The @option{compression_level} option can be used to control speed vs.
|
|
compression tradeoff, with the values mapped to libwavpack as follows:
|
|
|
|
@table @option
|
|
|
|
@item 0
|
|
Fast mode - corresponding to the wavpack @option{-f} option.
|
|
|
|
@item 1
|
|
Normal (default) settings.
|
|
|
|
@item 2
|
|
High quality - corresponding to the wavpack @option{-h} option.
|
|
|
|
@item 3
|
|
Very high quality - corresponding to the wavpack @option{-hh} option.
|
|
|
|
@item 4-8
|
|
Same as 3, but with extra processing enabled - corresponding to the wavpack
|
|
@option{-x} option. I.e. 4 is the same as @option{-x2} and 8 is the same as
|
|
@option{-x6}.
|
|
|
|
@end table
|
|
|
|
@c man end AUDIO ENCODERS
|
|
|
|
@chapter Video Encoders
|
|
@c man begin VIDEO ENCODERS
|
|
|
|
A description of some of the currently available video encoders
|
|
follows.
|
|
|
|
@section libtheora
|
|
|
|
Theora format supported through libtheora.
|
|
|
|
Requires the presence of the libtheora headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libtheora}.
|
|
|
|
@subsection Options
|
|
|
|
The following global options are mapped to internal libtheora options
|
|
which affect the quality and the bitrate of the encoded stream.
|
|
|
|
@table @option
|
|
@item b
|
|
Set the video bitrate, only works if the @code{qscale} flag in
|
|
@option{flags} is not enabled.
|
|
|
|
@item flags
|
|
Used to enable constant quality mode encoding through the
|
|
@option{qscale} flag, and to enable the @code{pass1} and @code{pass2}
|
|
modes.
|
|
|
|
@item g
|
|
Set the GOP size.
|
|
|
|
@item global_quality
|
|
Set the global quality in lambda units, only works if the
|
|
@code{qscale} flag in @option{flags} is enabled. The value is clipped
|
|
in the [0 - 10*@code{FF_QP2LAMBDA}] range, and then multiplied for 6.3
|
|
to get a value in the native libtheora range [0-63]. A higher value
|
|
corresponds to a higher quality.
|
|
|
|
For example, to set maximum constant quality encoding with
|
|
@command{ffmpeg}:
|
|
@example
|
|
ffmpeg -i INPUT -flags:v qscale -global_quality:v "10*QP2LAMBDA" -codec:v libtheora OUTPUT.ogg
|
|
@end example
|
|
@end table
|
|
|
|
@section libvpx
|
|
|
|
VP8 format supported through libvpx.
|
|
|
|
Requires the presence of the libvpx headers and library during configuration.
|
|
You need to explicitly configure the build with @code{--enable-libvpx}.
|
|
|
|
@subsection Options
|
|
|
|
Mapping from FFmpeg to libvpx options with conversion notes in parentheses.
|
|
|
|
@table @option
|
|
|
|
@item threads
|
|
g_threads
|
|
|
|
@item profile
|
|
g_profile
|
|
|
|
@item vb
|
|
rc_target_bitrate
|
|
|
|
@item g
|
|
kf_max_dist
|
|
|
|
@item keyint_min
|
|
kf_min_dist
|
|
|
|
@item qmin
|
|
rc_min_quantizer
|
|
|
|
@item qmax
|
|
rc_max_quantizer
|
|
|
|
@item bufsize, vb
|
|
rc_buf_sz
|
|
@code{(bufsize * 1000 / vb)}
|
|
|
|
rc_buf_optimal_sz
|
|
@code{(bufsize * 1000 / vb * 5 / 6)}
|
|
|
|
@item rc_init_occupancy, vb
|
|
rc_buf_initial_sz
|
|
@code{(rc_init_occupancy * 1000 / vb)}
|
|
|
|
@item rc_buffer_aggressivity
|
|
rc_undershoot_pct
|
|
|
|
@item skip_threshold
|
|
rc_dropframe_thresh
|
|
|
|
@item qcomp
|
|
rc_2pass_vbr_bias_pct
|
|
|
|
@item maxrate, vb
|
|
rc_2pass_vbr_maxsection_pct
|
|
@code{(maxrate * 100 / vb)}
|
|
|
|
@item minrate, vb
|
|
rc_2pass_vbr_minsection_pct
|
|
@code{(minrate * 100 / vb)}
|
|
|
|
@item minrate, maxrate, vb
|
|
@code{VPX_CBR}
|
|
@code{(minrate == maxrate == vb)}
|
|
|
|
@item crf
|
|
@code{VPX_CQ}, @code{VP8E_SET_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}
|
|
@end table
|
|
|
|
@item speed
|
|
@code{VP8E_SET_CPUUSED}
|
|
|
|
@item nr
|
|
@code{VP8E_SET_NOISE_SENSITIVITY}
|
|
|
|
@item mb_threshold
|
|
@code{VP8E_SET_STATIC_THRESHOLD}
|
|
|
|
@item slices
|
|
@code{VP8E_SET_TOKEN_PARTITIONS}
|
|
|
|
@item max-intra-rate
|
|
@code{VP8E_SET_MAX_INTRA_BITRATE_PCT}
|
|
|
|
@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
|
|
|
|
@end table
|
|
|
|
For more information about libvpx see:
|
|
@url{http://www.webmproject.org/}
|
|
|
|
@section libx264
|
|
|
|
x264 H.264/MPEG-4 AVC encoder wrapper.
|
|
|
|
Requires the presence of the libx264 headers and library during
|
|
configuration. You need to explicitly configure the build with
|
|
@code{--enable-libx264}.
|
|
|
|
x264 supports an impressive number of features, including 8x8 and 4x4 adaptive
|
|
spatial transform, adaptive B-frame placement, CAVLC/CABAC entropy coding,
|
|
interlacing (MBAFF), lossless mode, psy optimizations for detail retention
|
|
(adaptive quantization, psy-RD, psy-trellis).
|
|
|
|
The FFmpeg wrapper provides a mapping for most of them using global options
|
|
that match those of the encoders and provides private options for the unique
|
|
encoder options. Additionally an expert override is provided to directly pass
|
|
a list of key=value tuples as accepted by x264_param_parse.
|
|
|
|
@subsection Option Mapping
|
|
|
|
The following options are supported by the x264 wrapper, the x264-equivalent
|
|
options follow the FFmpeg ones.
|
|
|
|
@multitable @columnfractions .2 .2
|
|
@item b @tab bitrate
|
|
FFmpeg @code{b} option is expressed in bits/s, x264 @code{bitrate} in kilobits/s.
|
|
@item bf @tab bframes
|
|
Maximum number of B-frames.
|
|
@item g @tab keyint
|
|
Maximum GOP size.
|
|
@item qmin @tab qpmin
|
|
@item qmax @tab qpmax
|
|
@item qdiff @tab qpstep
|
|
@item qblur @tab qblur
|
|
@item qcomp @tab qcomp
|
|
@item refs @tab ref
|
|
@item sc_threshold @tab scenecut
|
|
@item trellis @tab trellis
|
|
@item nr @tab nr
|
|
Noise reduction.
|
|
@item me_range @tab merange
|
|
@item me_method @tab me
|
|
@item subq @tab subme
|
|
@item b_strategy @tab b-adapt
|
|
@item keyint_min @tab keyint-min
|
|
@item coder @tab cabac
|
|
Set coder to @code{ac} to use CABAC.
|
|
@item cmp @tab chroma-me
|
|
Set to @code{chroma} to use chroma motion estimation.
|
|
@item threads @tab threads
|
|
@item thread_type @tab sliced_threads
|
|
Set to @code{slice} to use sliced threading instead of frame threading.
|
|
@item flags -cgop @tab open-gop
|
|
Set @code{-cgop} to use recovery points to close GOPs.
|
|
@item rc_init_occupancy @tab vbv-init
|
|
Initial buffer occupancy.
|
|
@end multitable
|
|
|
|
@subsection Private Options
|
|
@table @option
|
|
@item -preset @var{string}
|
|
Set the encoding preset (cf. x264 --fullhelp).
|
|
@item -tune @var{string}
|
|
Tune the encoding params (cf. x264 --fullhelp).
|
|
@item -profile @var{string}
|
|
Set profile restrictions (cf. x264 --fullhelp).
|
|
@item -fastfirstpass @var{integer}
|
|
Use fast settings when encoding first pass.
|
|
@item -crf @var{float}
|
|
Select the quality for constant quality mode.
|
|
@item -crf_max @var{float}
|
|
In CRF mode, prevents VBV from lowering quality beyond this point.
|
|
@item -qp @var{integer}
|
|
Constant quantization parameter rate control method.
|
|
@item -aq-mode @var{integer}
|
|
AQ method
|
|
|
|
Possible values:
|
|
@table @samp
|
|
@item none
|
|
|
|
@item variance
|
|
Variance AQ (complexity mask).
|
|
@item autovariance
|
|
Auto-variance AQ (experimental).
|
|
@end table
|
|
@item -aq-strength @var{float}
|
|
AQ strength, reduces blocking and blurring in flat and textured areas.
|
|
@item -psy @var{integer}
|
|
Use psychovisual optimizations.
|
|
@item -psy-rd @var{string}
|
|
Strength of psychovisual optimization, in <psy-rd>:<psy-trellis> format.
|
|
@item -rc-lookahead @var{integer}
|
|
Number of frames to look ahead for frametype and ratecontrol.
|
|
@item -weightb @var{integer}
|
|
Weighted prediction for B-frames.
|
|
@item -weightp @var{integer}
|
|
Weighted prediction analysis method.
|
|
|
|
Possible values:
|
|
@table @samp
|
|
@item none
|
|
|
|
@item simple
|
|
|
|
@item smart
|
|
|
|
@end table
|
|
@item -ssim @var{integer}
|
|
Calculate and print SSIM stats.
|
|
@item -intra-refresh @var{integer}
|
|
Use Periodic Intra Refresh instead of IDR frames.
|
|
@item -b-bias @var{integer}
|
|
Influences how often B-frames are used.
|
|
@item -b-pyramid @var{integer}
|
|
Keep some B-frames as references.
|
|
|
|
Possible values:
|
|
@table @samp
|
|
@item none
|
|
|
|
@item strict
|
|
Strictly hierarchical pyramid.
|
|
@item normal
|
|
Non-strict (not Blu-ray compatible).
|
|
@end table
|
|
@item -mixed-refs @var{integer}
|
|
One reference per partition, as opposed to one reference per macroblock.
|
|
@item -8x8dct @var{integer}
|
|
High profile 8x8 transform.
|
|
@item -fast-pskip @var{integer}
|
|
@item -aud @var{integer}
|
|
Use access unit delimiters.
|
|
@item -mbtree @var{integer}
|
|
Use macroblock tree ratecontrol.
|
|
@item -deblock @var{string}
|
|
Loop filter parameters, in <alpha:beta> form.
|
|
@item -cplxblur @var{float}
|
|
Reduce fluctuations in QP (before curve compression).
|
|
@item -partitions @var{string}
|
|
A comma-separated list of partitions to consider, possible values: p8x8, p4x4, b8x8, i8x8, i4x4, none, all.
|
|
@item -direct-pred @var{integer}
|
|
Direct MV prediction mode
|
|
|
|
Possible values:
|
|
@table @samp
|
|
@item none
|
|
|
|
@item spatial
|
|
|
|
@item temporal
|
|
|
|
@item auto
|
|
|
|
@end table
|
|
@item -slice-max-size @var{integer}
|
|
Limit the size of each slice in bytes.
|
|
@item -stats @var{string}
|
|
Filename for 2 pass stats.
|
|
@item -nal-hrd @var{integer}
|
|
Signal HRD information (requires vbv-bufsize; cbr not allowed in .mp4).
|
|
|
|
Possible values:
|
|
@table @samp
|
|
@item none
|
|
|
|
@item vbr
|
|
|
|
@item cbr
|
|
|
|
@end table
|
|
|
|
@item x264opts @var{options}
|
|
Allow to set any x264 option, see @code{x264 --fullhelp} for a list.
|
|
|
|
@var{options} is a list of @var{key}=@var{value} couples separated by
|
|
":". In @var{filter} and @var{psy-rd} options that use ":" as a separator
|
|
themselves, use "," instead. They accept it as well since long ago but this
|
|
is kept undocumented for some reason.
|
|
|
|
For example to specify libx264 encoding options with @command{ffmpeg}:
|
|
@example
|
|
ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
|
|
@end example
|
|
|
|
For more information about libx264 and the supported options see:
|
|
@url{http://www.videolan.org/developers/x264.html}
|
|
|
|
@item -x264-params @var{string}
|
|
Override the x264 configuration using a :-separated list of key=value parameters.
|
|
@example
|
|
-x264-params level=30:bframes=0:weightp=0:cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:no-fast-pskip=1:subq=6:8x8dct=0:trellis=0
|
|
@end example
|
|
@end table
|
|
|
|
Encoding avpresets for common usages are provided so they can be used with the
|
|
general presets system (e.g. passing the @code{-pre} option).
|
|
|
|
@section png
|
|
|
|
PNG image encoder.
|
|
|
|
@subsection Private options
|
|
|
|
@table @option
|
|
@item dpi @var{integer}
|
|
Set physical density of pixels, in dots per inch, unset by default
|
|
@item dpm @var{integer}
|
|
Set physical density of pixels, in dots per meter, unset by default
|
|
@end table
|
|
|
|
@section ProRes
|
|
|
|
Apple ProRes encoder.
|
|
|
|
FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder.
|
|
The used encoder can be choosen with the @code{-vcodec} option.
|
|
|
|
@subsection Private Options for prores-ks
|
|
|
|
@table @option
|
|
@item profile @var{integer}
|
|
Select the ProRes profile to encode
|
|
@table @samp
|
|
@item proxy
|
|
@item lt
|
|
@item standard
|
|
@item hq
|
|
@item 4444
|
|
@end table
|
|
|
|
@item quant_mat @var{integer}
|
|
Select quantization matrix.
|
|
@table @samp
|
|
@item auto
|
|
@item default
|
|
@item proxy
|
|
@item lt
|
|
@item standard
|
|
@item hq
|
|
@end table
|
|
If set to @var{auto}, the matrix matching the profile will be picked.
|
|
If not set, the matrix providing the highest quality, @var{default}, will be
|
|
picked.
|
|
|
|
@item bits_per_mb @var{integer}
|
|
How many bits to allot for coding one macroblock. Different profiles use
|
|
between 200 and 2400 bits per macroblock, the maximum is 8000.
|
|
|
|
@item mbs_per_slice @var{integer}
|
|
Number of macroblocks in each slice (1-8); the default value (8)
|
|
should be good in almost all situations.
|
|
|
|
@item vendor @var{string}
|
|
Override the 4-byte vendor ID.
|
|
A custom vendor ID like @var{apl0} would claim the stream was produced by
|
|
the Apple encoder.
|
|
|
|
@item alpha_bits @var{integer}
|
|
Specify number of bits for alpha component.
|
|
Possible values are @var{0}, @var{8} and @var{16}.
|
|
Use @var{0} to disable alpha plane coding.
|
|
|
|
@end table
|
|
|
|
@subsection Speed considerations
|
|
|
|
In the default mode of operation the encoder has to honor frame constraints
|
|
(i.e. not produc frames with size bigger than requested) while still making
|
|
output picture as good as possible.
|
|
A frame containing a lot of small details is harder to compress and the encoder
|
|
would spend more time searching for appropriate quantizers for each slice.
|
|
|
|
Setting a higher @option{bits_per_mb} limit will improve the speed.
|
|
|
|
For the fastest encoding speed set the @option{qscale} parameter (4 is the
|
|
recommended value) and do not set a size constraint.
|
|
|
|
@c man end VIDEO ENCODERS
|