twolame (1) - Linux Man Pages
twolame: an optimised MPEG Audio Layer 2 (MP2) encoder
twolame - an optimised MPEG Audio Layer 2 (MP2) encoder
TwoLAME is an optimised MPEG Audio Layer 2 (MP2) encoder based on tooLAME by Mike Cheng, which in turn is based upon the ISO dist10 code and portions of LAME. Encoding is performed by the libtwolame library backend.
- Specifies that input is raw signed PCM audio. If audio is stereo, than audio samples are interleaved between the two channels.
- Force byte-swapping of the input. Endian detection is performed automatically by libsndfile, so this option shouldn't normally be needed.
-s, --samplerate <int>
- If inputting raw PCM sound, you must specify the sample rate of the audio in Hz. Valid sample rates: 16000, 22050, 24000, 32000, 44100, 48000Hz. Default sample rate is 44100Hz.
- Specifies the sample size (in bits) of the raw PCM audio. Valid sample sizes: 8, 16, 24, 32. Default sample size is 16-bit.
-N, --channels <int>
- If inputting raw PCM sound, you must specify the number of channels in the input audio. Default number of channels is 2.
- Swap the Left and Right channels of a stereo input file.
- Scale the input audio prior to encoding. All of the input audio is multiplied by specified value. Value between 0 and 1 will reduce the audio gain, and a value above 1 will increase the gain of the audio.
- Same as --scale, but only affects the left channel.
- Same as --scale, but only affects the right channel.
-m, --mode <char>
Choose the mode of the resulting audio. Default is auto.
- • "a" auto - choose mode automatically based on the input
- • "s" stereo
- • "d" dual channel
- • "j" joint stereo
- • "m" mono
- If the input file is stereo then, downmix the left and right input channels into a single mono channel.
-b, --bitrate <int>
Sets the total bitrate (in kbps) for the output file. The default bitrate depends on the number of input channels and samplerate.
------------------------------ Sample Rate Mono Stereo ------------------------------ 48000 96 192 44100 96 192 32000 80 160 24000 48 96 22050 48 96 16000 32 64 ------------------------------
-P, --psyc-mode <int>
- Choose the psycho-acoustic model to use (-1 to 4). Model number -1 is turns off psycho-acoustic modelling and uses fixed default values instead. Please see the file psycho for a full description of each of the models available. Default model is 3.
- Enable VBR mode. See vbr documentation file for details. Default VBR level is 5.0.
-V, --vbr-level <float>
- Enable VBR mode and set quality level. The higher the number the better the quality. Maximum range is -50 to 50 but useful range is -10 to 10. See vbr documentation file for details.
-l, --ath <float>
- Set the ATH level. Default level is 0.0.
-q, --quick <int>
- Enable quick mode. Only re-calculate psycho-acoustic model every specified number of frames.
- Enables single frame mode: only a single frame of MPEG audio is output and then the program terminates.
- Turn on Copyright flag in output bitstream.
- Turn off Original flag in output bitstream.
- Turn on Original flag in output bitstream.
- Enable CRC error protection in output bitstream. An extra 16-bit checksum is added to frames.
- Turn on padding in output bitstream.
-R, --reserve <int>
- Reserve specified number of bits in the each from of the output bitstream.
-e, --deemphasis <char>
- Set the de-emphasis type (n/c/5). Default is none.
- Turn on energy level extensions.
-t, --talkativity <int>
- Set the amount of information to be displayed on stderr (0 to 10). Default is 2.
- Don't send any messages to stderr, unless there is an error. (Same as --talkativity=0)
- Only display a minimal number of messages while encoding. This setting is quieter than the default talkativity setting. (Same as --talkativity=1)
- Display an increased number of messages on stderr. This setting is useful to diagnose problems. (Same as --talkativity=4)
If encoding completes successfully, then twolame will return 0. However if encoding is not successful, then it will return one of the following codes.
- • 1 (No encoding performed)
- • 2 (Error opening input file)
- • 4 (Error opening output file)
- • 6 (Error allocating memory)
- • 8 (Error in chosen encoding parameters)
- • 10 (Error reading input audio)
- • 12 (Error occured while encoding)
- • 14 (Error writing output audio)
This will encode sound.wav to sound.mp2 using the default constant bitrate of 192 kbps and using the default psycho-acoustic model (model 3):
Constant bitrate of 160kbps and joint stereo encoding, saved to file sound_160.mp2:
twolame -b 160 -m j sound.aiff sound_160.mp2
Encode sound.wav to newfile.mp2 using psycho-acoustic model 2 and encoding with variable bitrate:
twolame -P 2 -v sound.wav newfile.mp2
Same as example above, except that the negative value of the "-V" argument means that the lower bitrates will be favoured over the higher ones:
twolame -P 2 -V -5 sound.wav newfile.mp2
Resample audio file using sox and pipe straight through twolame:
sox sound_11025.aiff -t raw -r 16000 | twolame -r -s 16000 - - > out.mp2
TwoLAME web site: m[blue]http://www.twolame.org/m
Nicholas J Humfrey <njh [at] aelius.com>