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lame

Section: LAME audio compressor (1)
Updated: July 08, 2008
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NAME

lame - create mp3 audio files

SYNOPSIS

lame [options] <infile> <outfile>

DESCRIPTION

LAME is a program which can be used to create compressed audio files. (Lame ain't an MP3 encoder). These audio files can be played back by popular MP3 players such as mpg123 or madplay. To read from stdin, use "-" for <infile>. To write to stdout, use "-" for <outfile>.

OPTIONS

Input options:

-r

Assume the input file is raw pcm. Sampling rate and mono/stereo/jstereo must be specified on the command line. For each stereo sample, LAME expects the input data to be ordered left channel first, then right channel. By default, LAME expects them to be signed integers with a bitwidth of 16. Without -r, LAME will perform several fseek()'s on the input file looking for WAV and AIFF headers.
Might not be available on your release.

-x

Swap bytes in the input file or output file when using --decode.
For sorting out little endian/big endian type problems. If your encodings sounds like static, try this first.
Without using -x, LAME will treat input file as native endian.

-s sfreq

sfreq = 8/11.025/12/16/22.05/24/32/44.1/48

Required only for raw PCM input files. Otherwise it will be determined from the header of the input file.

LAME will automatically resample the input file to one of the supported MP3 samplerates if necessary.

--bitwidth n

Input bit width per sample.
n = 8, 16, 24, 32 (default 16)

Required only for raw PCM input files. Otherwise it will be determined from the header of the input file.

--signed

Instructs LAME that the samples from the input are signed (the default for 16, 24 and 32 bits raw pcm data).

Required only for raw PCM input files.

--unsigned

Instructs LAME that the samples from the input are unsigned (the default for 8 bits raw pcm data, where 0x80 is zero).

Required only for raw PCM input files and only available at bitwidth 8.

--little-endian

Instructs LAME that the samples from the input are in little-endian form.

Required only for raw PCM input files.

--big-endian

Instructs LAME that the samples from the input are in big-endian form.

Required only for raw PCM input files.

--mp2input

Assume the input file is a MPEG Layer II (ie MP2) file.
If the filename ends in ".mp2" LAME will assume it is a MPEG Layer II file. For stdin or Layer II files which do not end in .mp2 you need to use this switch.

--mp3input

Assume the input file is a MP3 file.
Useful for downsampling from one mp3 to another. As an example, it can be useful for streaming through an IceCast server.
If the filename ends in ".mp3" LAME will assume it is an MP3. For stdin or MP3 files which do not end in .mp3 you need to use this switch.

--nogap file1 file2 ...

gapless encoding for a set of contiguous files

--nogapout dir

output dir for gapless encoding (must precede --nogap)

Operational options:

-m mode

mode = s, j, f, d, m, l, r

Joint-stereo is the default mode for stereo files with VBR when -V is more than 4 or fixed bitrates of 160kbs or less. At higher fixed bitrates or higher VBR settings, the default is stereo.

(s)imple stereo
In this mode, the encoder makes no use of potentially existing correlations between the two input channels. It can, however, negotiate the bit demand between both channel, i.e. give one channel more bits if the other contains silence or needs less bits because of a lower complexity.

(j)oint stereo
In this mode, the encoder will make use of a correlation between both channels. The signal will be matrixed into a sum ("mid"), computed by L+R, and difference ("side") signal, computed by L-R, and more bits are allocated to the mid channel. This will effectively increase the bandwidth if the signal does not have too much stereo separation, thus giving a significant gain in encoding quality.

Using mid/side stereo inappropriately can result in audible compression artifacts. To much switching between mid/side and regular stereo can also sound bad. To determine when to switch to mid/side stereo, LAME uses a much more sophisticated algorithm than that described in the ISO documentation, and thus is safe to use in joint stereo mode.

(f)orced MS stereo
This mode will force MS stereo on all frames. It is slightly faster than joint stereo, but it should be used only if you are sure that every frame of the input file has very little stereo separation.

(d)ual mono
In this mode, the 2 channels will be totally independently encoded. Each channel will have exactly half of the bitrate. This mode is designed for applications like dual languages encoding (for example: English in one channel and French in the other). Using this encoding mode for regular stereo files will result in a lower quality encoding.

(m)ono
The input will be encoded as a mono signal. If it was a stereo signal, it will be downsampled to mono. The downmix is calculated as the sum of the left and right channel, attenuated by 6 dB.

(l)eft channel only
The input will be encoded as a mono signal. If it was a stereo signal, the left channel will be encoded only.

(r)ight channel only
The input will be encoded as a mono signal. If it was a stereo signal, the right channel will be encoded only.

-a

Mix the stereo input file to mono and encode as mono.
The downmix is calculated as the sum of the left and right channel, attenuated by 6 dB.

This option is only needed in the case of raw PCM stereo input (because LAME cannot determine the number of channels in the input file). To encode a stereo PCM input file as mono, use lame -m s -a.

For WAV and AIFF input files, using -m will always produce a mono .mp3 file from both mono and stereo input.

-d

Allows the left and right channels to use different block size types.

--freeformat

Produces a free format bitstream. With this option, you can use -b with any bitrate higher than 8 kbps.

However, even if an mp3 decoder is required to support free bitrates at least up to 320 kbps, many players are unable to deal with it.

Tests have shown that the following decoders support free format:
FreeAmp up to 440 kbps
in_mpg123 up to 560 kbps
l3dec up to 310 kbps
LAME up to 560 kbps
MAD up to 640 kbps

--decode

Uses LAME for decoding to a wav file. The input file can be any input type supported by encoding, including layer II files. LAME uses a bugfixed version of mpglib for decoding.

If -t is used (disable wav header), LAME will output raw pcm in native endian format. You can use -x to swap bytes order.

This option is not usable if the MP3 decoder was explicitly disabled in the build of LAME.

-t

Disable writing of the INFO Tag on encoding.
This tag in embedded in frame 0 of the MP3 file. It includes some information about the encoding options of the file, and in VBR it lets VBR aware players correctly seek and compute playing times of VBR files.

When --decode is specified (decode to WAV), this flag will disable writing of the WAV header. The output will be raw pcm, native endian format. Use -x to swap bytes.

--comp arg

Instead of choosing bitrate, using this option, user can choose compression ratio to achieve.

--scale n

--scale-l n

--scale-r n

Scales input (every channel, only left channel or only right channel) by n. This just multiplies the PCM data (after it has been converted to floating point) by n.

n > 1: increase volume
n = 1: no effect
n < 1: reduce volume

Use with care, since most MP3 decoders will truncate data which decodes to values greater than 32768.

--replaygain-fast

Compute ReplayGain fast but slightly inaccurately.

This computes "Radio" ReplayGain on the input data stream after user-specified volume-scaling and/or resampling.

The ReplayGain analysis does not affect the content of a compressed data stream itself, it is a value stored in the header of a sound file. Information on the purpose of ReplayGain and the algorithms used is available from http://www.replaygain.org/.

Only the "RadioGain" Replaygain value is computed, it is stored in the LAME tag. The analysis is performed with the reference volume equal to 89dB. Note: the reference volume has been changed from 83dB on transition from version 3.95 to 3.95.1.

This switch is enabled by default.

See also: --replaygain-accurate, --noreplaygain

--replaygain-accurate

Compute ReplayGain more accurately and find the peak sample.

This enables decoding on the fly, computes "Radio" ReplayGain on the decoded data stream, finds the peak sample of the decoded data stream and stores it in the file.
The ReplayGain analysis does not affect the content of a compressed data stream itself, it is a value stored in the header of a sound file. Information on the purpose of ReplayGain and the algorithms used is available from http://www.replaygain.org/.

By default, LAME performs ReplayGain analysis on the input data (after the user-specified volume scaling). This behavior might give slightly inaccurate results because the data on the output of a lossy compression/decompression sequence differs from the initial input data. When --replaygain-accurate is specified the mp3 stream gets decoded on the fly and the analysis is performed on the decoded data stream. Although theoretically this method gives more accurate results, it has several disadvantages:

*: tests have shown that the difference between the ReplayGain values computed on the input data and decoded data is usually not greater than 0.5dB, although the minimum volume difference the human ear can perceive is about 1.0dB
*: decoding on the fly significantly slows down the encoding process

: The apparent advantage is that:

*: with --replaygain-accurate the real peak sample is determined and stored in the file. The knowledge of the peak sample can be useful to decoders (players) to prevent a negative effect called 'clipping' that introduces distortion into the sound.

: Only the "RadioGain" ReplayGain value is computed, it is stored in the LAME tag. The analysis is performed with the reference volume equal to 89dB. Note: the reference volume has been changed from 83dB on transition from version 3.95 to 3.95.1.
This option is not usable if the MP3 decoder was explicitly disabled in the build of LAME. (Note: if LAME is compiled without the MP3 decoder, ReplayGain analysis is performed on the input data after user-specified volume scaling).
See also: --replaygain-fast, --noreplaygain --clipdetect

--noreplaygain

Disable ReplayGain analysis.

By default ReplayGain analysis is enabled. This switch disables it.

See also: --replaygain-fast, --replaygain-accurate

--clipdetect

Clipping detection.

Enable --replaygain-accurate and print a message whether clipping occurs and how far in dB the waveform is from full scale.
This option is not usable if the MP3 decoder was explicitly disabled in the build of LAME.

ID3 TAGS

LAME is able to embed ID3 v1, v1.1 or v2 tags inside the encoded MP3 file. This allows to have some useful information about the music track included inside the file. Those data can be read by most MP3 players.

Lame will smartly choose which tags to use. It will add ID3 v2 tags only if the input comments won't fit in v1 or v1.1 tags, i.e. if they are more than 30 characters. In this case, both v1 and v2 tags will be added, to ensure reading of tags by MP3 players which are unable to read ID3 v2 tags.

ENCODING MODES

LAME is able to encode your music using one of its 3 encoding modes: constant bitrate (CBR), average bitrate (ABR) and variable bitrate (VBR).

Constant Bitrate (CBR): This is the default encoding mode, and also the most basic. In this mode, the bitrate will be the same for the whole file. It means that each part of your mp3 file will be using the same number of bits. The musical passage being a difficult one to encode or an easy one, the encoder will use the same bitrate, so the quality of your mp3 is variable. Complex parts will be of a lower quality than the easiest ones. The main advantage is that the final files size won't change and can be accurately predicted.
Average Bitrate (ABR): In this mode, you choose the encoder will maintain an average bitrate while using higher bitrates for the parts of your music that need more bits. The result will be of higher quality than CBR encoding but the average file size will remain predictable, so this mode is highly recommended over CBR. This encoding mode is similar to what is referred as vbr in AAC or Liquid Audio (2 other compression technologies).
Variable bitrate (VBR): In this mode, you choose the desired quality on a scale from 9 (lowest quality/biggest distortion) to 0 (highest quality/lowest distortion). Then encoder tries to maintain the given quality in the whole file by choosing the optimal number of bits to spend for each part of your music. The main advantage is that you are able to specify the quality level that you want to reach, but the inconvenient is that the final file size is totally unpredictable.

PRESETS

The --preset switches are aliases over LAME settings.

To activate these presets:

For VBR modes (generally highest quality):

--preset medium: This preset should provide near transparency to most people on most music.
--preset standard: This preset should generally be transparent to most people on most music and is already quite high in quality.
--preset extreme: If you have extremely good hearing and similar equipment, this preset will generally provide slightly higher quality than the standard mode.

For CBR 320kbps (highest quality possible from the --preset switches):

--preset insane: This preset will usually be overkill for most people and most situations, but if you must have the absolute highest quality with no regard to filesize, this is the way to go.

For ABR modes (high quality per given bitrate but not as high as VBR):

--preset kbps: Using this preset will usually give you good quality at a specified bitrate. Depending on the bitrate entered, this preset will determine the optimal settings for that particular situation. While this approach works, it is not nearly as flexible as VBR, and usually will not attain the same level of quality as VBR at higher bitrates.

The following options are also available for the corresponding profiles:

standard|extreme
cbr kbps

cbr

If you use the ABR mode (read above) with a significant bitrate such as 80, 96, 112, 128, 160, 192, 224, 256, 320, you can use the cbr option to force CBR mode encoding instead of the standard ABR mode. ABR does provide higher quality but CBR may be useful in situations such as when streaming an MP3 over the Internet may be important.

EXAMPLES

Fixed bit rate jstereo 128kbs encoding:

: lame sample.wav sample.mp3

Fixed bit rate jstereo 128 kbps encoding, highest quality (recommended):

: lame -h sample.wav sample.mp3

Fixed bit rate jstereo 112 kbps encoding:

: lame -b 112 sample.wav sample.mp3

To disable joint stereo encoding (slightly faster, but less quality at bitrates <= 128 kbps):

: lame -m s sample.wav sample.mp3

Fast encode, low quality (no psycho-acoustics):

: lame -f sample.wav sample.mp3

Variable bitrate (use -V n to adjust quality/filesize):

: lame -h -V 6 sample.wav sample.mp3

Streaming mono 22.05 kHz raw pcm, 24 kbps output:

: cat inputfile | lame -r -m m -b 24 -s 22.05 - - > output

Streaming mono 44.1 kHz raw pcm, with downsampling to 22.05 kHz:

: cat inputfile | lame -r -m m -b 24 --resample 22.05 - - > output

Encode with the standard preset:

: lame --preset standard sample.wav sample.mp3

BUGS

Probably there are some.

AUTHORS

LAME originally developed by Mike Cheng and now maintained by
Mark Taylor, and the LAME team.

GPSYCHO psycho-acoustic model by Mark Taylor.
(See http://www.mp3dev.org/).

mpglib by Michael Hipp

Manual page by William Schelter, Nils Faerber, Alexander Leidinger,
and Rog['e]rio Brito.

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lame

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

ID3 TAGS

ENCODING MODES

PRESETS

EXAMPLES

BUGS

SEE ALSO

AUTHORS

Index