MPEG-1 and/or MPEG-2 Audio Layer III, more commonly referred to as MP3, is an audio coding format for digital audio which uses a form of lossy data compression. It is a common audio format for consumer audio streaming or storage.
$ sudo apt-get install lame libmp3lame-dev
LAME is a high quality MPEG Audio Layer III (MP3) encoder licensed under the LGPL.
LAME features:
- Many improvements in quality in speed over ISO reference software. See history.
- MPEG1,2 and 2.5 layer III encoding.
- CBR (constant bitrate) and two types of variable bitrate, VBR and ABR.
- Encoding engine can be compiled as a shared library (Linux/UNIX), DLL , Directshow filter or ACM codec (Windows).
- Free format encoding and decoding.
- GPSYCHO: a GPL'd psycho acoustic and noise shaping model.
- Powerful and easy to use presets.
- Quality better than all other encoders at most bitrates.
- Fast! Encodes faster than real time on a PII 266 at highest quality mode.
- MP3x: a GTK/X-Window MP3 frame analyzer for both .mp3 and unencoded audio files.
$ sudo apt-get install madplay libmad0-dev
MAD (libmad) is a high-quality MPEG audio decoder. It currently supports MPEG-1 and the MPEG-2 extension to Lower Sampling Frequencies, as well as the so-called MPEG 2.5 format. All three audio layers (Layer I, Layer II, and Layer III a.k.a. MP3) are fully implemented.
MAD does not yet support MPEG-2 multichannel audio (although it should be backward compatible with such streams) nor does it currently support AAC.
MAD has the following special features:
- 24-bit PCM output
- 100% fixed-point (integer) computation
- completely new implementation based on the ISO/IEC standards
- distributed under the terms of the GNU General Public License (GPL)
http://m.baert.free.fr/contrib/docs/libmad/doxy/html/index.html
$ sudo apt-get install mpg123 libmpg123-dev
mpg123 is a console mpeg audio decoder/player.
libmpg123 is the decoder part of mpg123 is usable as a library in application.
Features include:
- decoding of MPEG 1.0/2.0/2.5 layer I/II/III audio streams to interleaved PCM, also free-format bitrates over 320 kbit/s
- sample-accurate seeking and gapless playback (via LAME Info frame)
- choice of sample encoding (from 8 bit µlaw to 32 bit float), mono mix
- build-time choice for integer or floating-point synth
- assembly/SIMD optimisations for common sample encodings and decoding modes
- choices between accuracy and efficiency (rounding modes, dithering)
- efficient 2:1 or 4:1 downsampling, sparing decoder work to evaluate the dropped samples
- n:m pseudo-resampler (repeat/drop samples without interpolation) as last resort to enable playback with enforced sample rate
- tune frequency scale factors for zero-cost equaliser (with 32 linearly-spaced bands given my MPEG; not pretty, but hey, it's free!)
- tune volume via scale factors, again without extra CPU cost
- parse and apply relative volume adjustment read from metadata (RVA2, ReplayGain)
- parse ID3v1, ID3v2 and ICY stream metadata (with configured interval), silenty skip other stuff
- graceful handling of stream errors (silence instead of whiny twittering)
- disabling of features to enable smaller builds for embedded systems (a generic x86-64 float-output binary of from mpg123-1.23.0 using gcc-4.9.2 with -Os is 118 KiB stripped, still with all the essential sample-accurate codec functionality)
mpg123 had claims of being very fast, MAD claimed it was very accurate.
Wesley Moore did a benchmark test on the performance of libmad and libmpg123, result on the post: http://www.wezm.net/technical/2008/04/mp3-decoder-libraries-compared/
| Size | 126,083,072 bytes |
|---|---|
| Bitrate | 224 kbps |
| Channels | 2 (Joint Stereo) |
| Length | 1:15:02 |
| Library | Average Elapsed Time | Average Processor Time | Processor Time Std. Deviation |
|---|---|---|---|
| mpg123 | 37.00 | 32.21 | 0.19 |
| mad | 100.10 | 94.44 | 0.15 |
| Core Audio | 84.00 | 78.34 | 0.34 |
http://www.wezm.net/technical/2008/04/mp3-decoder-libraries-compared/