8.3. MP3 Audio

Contributed by Chern Lee.

This section describes some MP3 players available for FreeBSD, how to rip audio CD tracks, and how to encode and decode MP3s.

8.3.1. MP3 Players

A popular graphical MP3 player is XMMS. It supports Winamp skins and additional plugins. The interface is intuitive, with a playlist, graphic equalizer, and more. Those familiar with Winamp will find XMMS simple to use. On FreeBSD, XMMS can be installed from the multimedia/xmms port or package.

The audio/mpg123 package or port provides an alternative, command-line MP3 player. Once installed, specify the MP3 file to play on the command line. If the system has multiple audio devices, the sound device can also be specifed:

# mpg123 -a /dev/dsp1.0 Foobar-GreatestHits.mp3
High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3
        version 1.18.1; written and copyright by Michael Hipp and others
        free software (LGPL) without any warranty but with best wishes

Playing MPEG stream from Foobar-GreatestHits.mp3 ...
MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo

Additional MP3 players are available in the FreeBSD Ports Collection.

8.3.2. Ripping CD Audio Tracks

Before encoding a CD or CD track to MP3, the audio data on the CD must be ripped to the hard drive. This is done by copying the raw CD Digital Audio (CDDA) data to WAV files.

The cdda2wav tool, which is installed with the sysutils/cdrtools suite, can be used to rip audio information from CDs.

With the audio CD in the drive, the following command can be issued as root to rip an entire CD into individual, per track, WAV files:

# cdda2wav -D 0,1,0 -B

In this example, the -D 0,1,0 indicates the SCSI device 0,1,0 containing the CD to rip. Use cdrecord -scanbus to determine the correct device parameters for the system.

To rip individual tracks, use -t to specify the track:

# cdda2wav -D 0,1,0 -t 7

To rip a range of tracks, such as track one to seven, specify a range:

# cdda2wav -D 0,1,0 -t 1+7

To rip from an ATAPI (IDE) CDROM drive, specify the device name in place of the SCSI unit numbers. For example, to rip track 7 from an IDE drive:

# cdda2wav -D /dev/acd0 -t 7

Alternately, dd can be used to extract audio tracks on ATAPI drives, as described in Section 18.5.5, “Duplicating Audio CDs”.

8.3.3. Encoding and Decoding MP3s

Lame is a popular MP3 encoder which can be installed from the audio/lame port. Due to patent issues, a package is not available.

The following command will convert the ripped WAV file audio01.wav to audio01.mp3:

# lame -h -b 128 --tt "Foo Song Title" --ta "FooBar Artist" --tl "FooBar Album" \
--ty "2014" --tc "Ripped and encoded by Foo" --tg "Genre" audio01.wav audio01.mp3

The specified 128 kbits is a standard MP3 bitrate while the 160 and 192 bitrates provide higher quality. The higher the bitrate, the larger the size of the resulting MP3. The -h turns on the higher quality but a little slower mode. The options beginning with --t indicate ID3 tags, which usually contain song information, to be embedded within the MP3 file. Additional encoding options can be found in the lame manual page.

In order to burn an audio CD from MP3s, they must first be converted to a non-compressed file format. XMMS can be used to convert to the WAV format, while mpg123 can be used to convert to the raw Pulse-Code Modulation (PCM) audio data format.

To convert audio01.mp3 using mpg123, specify the name of the PCM file:

# mpg123 -s audio01.mp3 > audio01.pcm

To use XMMS to convert a MP3 to WAV format, use these steps:

Procedure 8.1. Converting to WAV Format in XMMS
  1. Launch XMMS.

  2. Right-click the window to bring up the XMMS menu.

  3. Select Preferences under Options.

  4. Change the Output Plugin to Disk Writer Plugin.

  5. Press Configure.

  6. Enter or browse to a directory to write the uncompressed files to.

  7. Load the MP3 file into XMMS as usual, with volume at 100% and EQ settings turned off.

  8. Press Play. The XMMS will appear as if it is playing the MP3, but no music will be heard. It is actually playing the MP3 to a file.

  9. When finished, be sure to set the default Output Plugin back to what it was before in order to listen to MP3s again.

Both the WAV and PCM formats can be used with cdrecord. When using WAV files, there will be a small tick sound at the beginning of each track. This sound is the header of the WAV file. The audio/sox port or package can be used to remove the header:

% sox -t wav -r 44100 -s -w -c 2 track.wav track.raw

Refer to Section 18.5, “Creating and Using CD Media” for more information on using a CD burner in FreeBSD.

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