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Aften long help
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Aften long help
Wiesław Šoltés редактировал(а) эту страницу 2017-11-29 10:23:06 +01:00
Aften: A/52 audio encoder
Version git
(c) 2006-2009 Justin Ruggles, Prakash Punnoor, et al.
usage: aften [options] <input.wav> <output.ac3>
options:
CONSOLE OUTPUT OPTIONS
[-h] Print out list of commandline options.
[-longhelp] Print out commandline option details.
[-version] Print out the build version.
[-v #] Verbosity
This controls the level of console output to stderr.
0 - Quiet Mode. No output to stderr.
1 - Shows a running average of encoding statistics.
This is the default setting.
2 - Shows the statistics for each frame.
ENCODING OPTIONS
[-threads #] Number of threads
Aften can use multiple threads to speed up encoding.
By default, Aften uses one thread for each logical CPU
your system has, but you can override this value. A
value of 0 is the default and indicates that Aften
should try to detect the number of CPUs.
[-nosimd X] Comma-separated list of SIMD instruction sets not to use
Aften will auto-detect available SIMD instruction sets
for your CPU, so you shouldn't need to disable sets
explicitly - unless for speed or debugging reasons.
Available sets are mmx, sse, sse2, sse3 and altivec.
No spaces are allowed between the sets and the commas.
Example: -nosimd sse2,sse3
[-b #] CBR bitrate in kbps
CBR mode is selected by default. This option allows for
setting the fixed bitrate. The default bitrate depends
on the number of channels (not including LFE).
mono = 96 kbps
stereo = 192 kbps
3-channel = 256 kbps
4-channel = 384 kbps
5-channel = 448 kbps
[-q #] VBR quality
A value 0 to 1023 which corresponds to SNR offset, where
q=240 equates to an SNR offset of 0. 240 is the default
value. This scale will most likely be replaced in the
future with a better quality measurement.
[-fba #] Fast bit allocation
Fast bit allocation is a less-accurate search method
for CBR bit allocation. It only narrows down the SNR
value to within 16 of the optimal value. The result
is lower overall quality, but faster encoding. This
may not give the same results each time when using
parallel encoding.
[-exps #] Exponent strategy search size
The encoder determines the best combination of
exponent strategies for a frame by searching through
a list of pre-defined exponent strategies. This option
controls the size of the list to be searched. The
value can range from 1 (lower quality but faster) to
32 (higher quality but slower). The default value is 8.
[-pad #] Start-of-stream padding
The AC-3 format uses an overlap/add cycle for encoding
each block. By default, Aften pads the delay buffer
with a block of silence to avoid inaccurate encoding
of the first frame of audio. If this behavior is not
wanted, it can be disabled. The pad value can be a
1 (default) to use padding or 0 to not use padding.
[-w #] Bandwidth
The bandwidth setting corresponds to the high-frequency
cutoff. Specifically, it sets the highest frequency bin
which is encoded. The AC-3 format uses a 512-point MDCT
which gives 256 frequency levels from 0 to 1/2 of the
samplerate. The formula to give the number of coded
frequency bins from bandwidth setting is:
(w * 3) + 73, which gives a range of 73 to 253
I hope to replace this setting with one where the user
specifies the actual cutoff frequency rather than the
bandwidth code.
There are 2 special values, -1 and -2.
When -1 is used, Aften automatically selects what
it thinks is an appropriate bandwidth. This is the
default setting.
When -2 is used, a bandwidth is chosen for each frame
based on CBR frame size and a target quality of 240.
Variable bandwidth cannot be used with VBR mode.
[-wmin #] Minimum bandwidth
For variable bandwidth mode (-2), this option sets the
minimum value for the bandwidth code. This allows the
user to avoid a harsh cutoff frequency by sacrificing
general audio quality. The default value is 0.
[-wmax #] Maximum bandwidth
For variable bandwidth mode (-2), this option sets the
maximum value for the bandwidth code. This can be used
to speed up encoding by using a lower value than 60,
which is the default.
[-m #] Stereo rematrixing
Using stereo rematrixing can increase quality by
removing redundant information between the left and
right channels. This technique is common in audio
encoding, and is sometimes called mid/side encoding.
When this setting is turned on, Aften adaptively turns
rematrixing on or off for each of 4 frequency bands for
each block. When this setting is turned off,
rematrixing is not used for any blocks. The default
value is 1.
[-s #] Block switching
The AC-3 format allows for 2 different types of MDCT
transformations to translate from time-domain to
frequency-domain. The default is a 512-point transform,
which gives better frequency resolution. There is also
a 256-point transform, which gives better time
resolution. The specification gives a suggested method
for determining when to use the 256-point transform.
When block switching is turned on, Aften uses the spec
method for selecting the 256-point MDCT. When it is
turned off, only the 512-point MDCT is used, which is
faster. Block switching is turned off by default.
BITSTREAM INFO METADATA
[-cmix #] Center mix level
When three front channels are in use, this code
indicates the nominal down mix level of the center
channel with respect to the left and right channels.
0 = -3.0 dB (default)
1 = -4.5 dB
2 = -6.0 dB
[-smix #] Surround mix level
If surround channels are in use, this code indicates
the nominal down mix level of the surround channels.
0 = -3 dB (default)
1 = -6 dB
2 = 0
[-dsur #] Dolby Surround mode
When operating in the two channel mode, this code
indicates whether or not the program has been encoded in
Dolby Surround. This information is not used by the
AC-3 decoder, but may be used by other portions of the
audio reproduction equipment.
0 = not indicated (default)
1 = not Dolby surround encoded
2 = Dolby surround encoded
DYNAMIC RANGE COMPRESSION AND DIALOG NORMALIZATION
[-dynrng #] Dynamic Range Compression profile
Dynamic Range Compression allows for the final output
dynamic range to be limited without sacrificing quality.
The full dynamic range audio is still encoded, but a
code is given for each block which tells the decoder to
adjust the output volume for that block. The encoder
must analyze the input audio to determine the best way
to compress the dynamic range based on the loudness and
type of input (film, music, speech).
0 = Film Light
1 = Film Standard
2 = Music Light
3 = Music Standard
4 = Speech
5 = None (default)
[-dnorm #] Dialog normalization [0 - 31] (default: 31)
The dialog normalization value sets the average dialog
level. The value is typically constant for a particular
audio program. The decoder has a target output dialog
level of -31dB, so if the dialog level is specified as
being -31dB already (default), the output volume is not
altered. Otherwise, the overall output volume is
decreased so that the dialog level is adjusted down to
-31dB.
INPUT OPTIONS
By default, information about the input file, such as the channel
configuration and data size, is determined by the input file wav header.
However, the basic WAVE format is limited in that it can only support
up to 4 GB of data and cannot specify all channel layouts possible in the
AC-3 format. The acmod, lfe, and chconfig options allow the user to
explicitly select the desired channel layout. This only controls the
interpretation of the input, so no downmixing or upmixing is done. The
readtoeof option overrides the header and lets the user specify that Aften
should keep reading data until the end-of-file.
[-acmod #] Audio coding mode (overrides wav header)
0 = 1+1 (Ch1,Ch2)
1 = 1/0 (C)
2 = 2/0 (L,R)
3 = 3/0 (L,R,C)
4 = 2/1 (L,R,S)
5 = 3/1 (L,R,C,S)
6 = 2/2 (L,R,SL,SR)
7 = 3/2 (L,R,C,SL,SR)
[-lfe #] Specify use of LFE channel (overrides wav header)
0 = LFE channel is not present
1 = LFE channel is present
[-chconfig X] Specify channel configuration (overrides wav header)
1+1 = (Ch1,Ch2)
1/0 = (C)
2/0 = (L,R)
3/0 = (L,R,C)
2/1 = (L,R,S)
3/1 = (L,R,C,S)
2/2 = (L,R,SL,SR)
3/2 = (L,R,C,SL,SR)
adding "+LFE" indicates use of the LFE channel
[-ch_X file] Add a mono file to the input list as the channel specified
These parameters are used to specify multiple mono
source files instead of a single multi-channel source
file. Only valid AC-3 combinations are allowed. The
acmod, lfe, chconfig, and chmap parameters are all
ignored if multi-mono inputs are used.
ch_fl = Front Left
ch_fc = Front Center
ch_fr = Front Right
ch_sl = Surround Left
ch_s = Surround
ch_sr = Surround Right
ch_m1 = Dual Mono Channel 1
ch_m2 = Dual Mono Channel 2
ch_lfe = LFE
[-raw_fmt X] Raw audio input sample format (default: s16_le)
This options specifies the sample format when using
raw audio input. Using this option forces Aften to
treat the input as raw audio. The choices for the
pre-defined sample formats are:
u8, s8, s16_le, s16_be, s20_le, s20_be, s24_le, s24_be,
s32_le, s32_be, float_le, float_be, double_le, double_be
[-raw_sr #] Raw audio input sample rate (default: 48000)
Using this option forces Aften to treat the input as
raw audio.
[-raw_ch #] Raw audio input channels (default: 1)
Using this option forces Aften to treat the input as
raw audio.
[-chmap #] Channel mapping order of input audio
Some programs create WAVE files which use a channel
mapping other than the standard WAVE mapping. This
option allows the user to specify if the input file
uses WAVE, AC-3, or MPEG channel mapping. The MPEG
channel mapping is used by DTS and by MPEG-2/4 formats
such as MP2 and AAC.
0 = WAVE mapping (default)
1 = AC-3 mapping
2 = MPEG mapping
[-readtoeof #] Read input WAVE audio data until the end-of-file.
This overrides the data size in the WAVE header, and
can be useful for streaming input or files larger than
4 GB.
0 = use data size in header (default)
1 = read data until end-of-file
INPUT FILTERS
[-bwfilter #] Specify use of the bandwidth low-pass filter
The bandwidth low-pass filter pre-filters the input
audio before converting to frequency-domain. This
smooths the cutoff frequency transition for slightly
better quality. When used with variable bandwidth
mode, the maximum bandwidth setting used as the cutoff
frequency.
0 = do not apply filter (default)
1 = apply filter
[-dcfilter #] Specify use of the DC high-pass filter
The DC high-pass filter is listed as optional by the
AC-3 specification. The implementation, as suggested,
is a single pole filter at 3 Hz.
0 = do not apply filter (default)
1 = apply filter
[-lfefilter #] Specify use of the LFE low-pass filter
The LFE low-pass filter is recommended by the AC-3
specification. The cutoff is 120 Hz. The specification
recommends an 8th order elliptic filter, but instead,
Aften uses a Butterworth 2nd order cascaded direct
form II filter.
0 = do not apply filter (default)
1 = apply filter
ALTERNATE BIT STREAM SYNTAX
The alternate bit stream syntax allows for encoding additional metadata by
adding 1 or 2 extended bitstream info sections to each frame.
[-xbsi1 #] Specify use of extended bitstream info 1
Extended bitstream info 1 contains the dmixmod,
ltrtcmix, ltrtsmix, lorocmix, and lorosmix fields. If
this option is turned on, all these values are written
to the output stream.
0 = do not write xbsi1
1 = write xbsi1
[-dmixmod #] Preferred stereo downmix mode
This code indicates the type of stereo downmix preferred
by the mastering engineer, and can be optionally used,
overridden, or ignored by the decoder.
0 = not indicated (default)
1 = Lt/Rt downmix preferred
2 = Lo/Ro downmix preferred
The 4 mix level options below all use the same code table:
0 = +3.0 dB
1 = +1.5 dB
2 = 0.0 dB
3 = -1.5 dB
4 = -3.0 dB (default)
5 = -4.5 dB
6 = -6.0 dB
7 = -inf dB
[-ltrtcmix #] Lt/Rt center mix level
This code indicates the nominal down mix level of the
center channel with respect to the left and right
channels in an Lt/Rt downmix.
[-ltrtsmix #] Lt/Rt surround mix level
This code indicates the nominal down mix level of the
surround channels with respect to the left and right
channels in an Lt/Rt downmix.
[-lorocmix #] Lo/Ro center mix level
This code indicates the nominal down mix level of the
center channel with respect to the left and right
channels in an Lo/Ro downmix.
[-lorosmix #] Lo/Ro surround mix level
This code indicates the nominal down mix level of the
surround channels with respect to the left and right
channels in an Lo/Ro downmix.
[-xbsi2 #] Specify use of extended bitstream info 2
Extended bitstream info 2 contains the dsurexmod,
dheadphon, and adconvtyp fields. If this option is
turned on, all these values are written to the output
stream. These options are not used by the AC-3 decoder,
but may be used by other portions of the audio
reproduction equipment.
0 = do not write xbsi2
1 = write xbsi2
[-dsurexmod #] Dolby Surround EX mode
This code indicates whether or not the program has been
encoded in Dolby Surround EX.
0 = not indicated (default)
1 = Not Dolby Surround EX encoded
2 = Dolby Surround EX encoded
[-dheadphon #] Dolby Headphone mode
This code indicates whether or not the program has been
Dolby Headphone-encoded.
0 = not indicated (default)
1 = Not Dolby Headphone encoded
2 = Dolby Headphone encoded
[-adconvtyp #] A/D converter type
This code indicates the type of A/D converter technology
used to capture the PCM audio.
0 = Standard (default)
1 = HDCD
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WAV to AC3 Encoder Copyright (C) 2007-2017 Wiesław Šoltés wieslaw.soltes@gmail.com