====== Audio - Fu ======

===== Convertimos wma a mp3 =====

<code bash>
mplayer -quiet INPUT.wma -ao pcm
lame -quiet audiodump.wav
mv audiodump.wav.mp3 OUTPUT.mp3 -v
rm audiodump.wav
</code>

===== Convertir un wav a un mp3 =====

<code bash>
ffmpeg -i INPUT.wav -acodec mp3 -ab 192k OUTPUT.mp3
</code>

===== Cortar un trozo de mp3 =====

<code bash>
ffmpeg -i Audio.mp3 -ss [segundo _de_inicio] -t [duración_del_corte] AudioCortado.mp3
</code>

===== De .mp3 a .amr =====

<code bash>
ffmpeg -i INPUT.mp3 \
    -acodec amr_nb \
        -ar 8000 \
        -ac 1 \
        -ab 32 \
    OUTPUT.amr
</code>

===== Une varios ficheros mp3 en uno =====

<code bash>
ffmpeg -i INPUT1.mp3 -i INPUT2.mp3 -i INPUT3.mp3 \
    OUTPUT.mp3
</code>

===== Adjust volume of audio file, gives a 5 dB gain =====

<code bash>
ffmpeg -i input.wav -af "volume=5dB" output.mp3
</code>

===== Combine multiple sources to one destination =====

<code bash>
ffmpeg -f concat -i /tmp/list.txt output3.flac
</code>

where list.txt contains:

<code>
  * file ‘/tmp/file1’
  * file ‘/tmp/file2’
</code>

or try:

<code bash>
ffmpeg -i "concat:input1.mpg|input2.mpg|input3.mpg" -c copy output.mpg
</code>

better still:

<code bash>
ffmpeg -f concat -i <( for f in *.wav; do echo "file '$(pwd)/$f'"; done ) output.wav
</code>

===== Convert .dsf files (SACD) to standard .wav files  =====

(PCM - CD quality). This however, does not give enough audio quality.

<code bash>
ffmpeg -i 04.dsf -acodec pcm_s16le -ar 44100 -ac 2 output.wav
</code>

===== Create multichannel WAVs or FLACs.  =====

This command will ‘rip’ the first 5 minutes (which is the first song actually)
of a quadraphonic (4.0) .WAV file that is 45 minutes long:

<code bash>
ffmpeg -i The\ Doobie\ Bothers-\ Toulouse\ Street.wav -acodec pcm_s16le -b:a 1400k -ss 0:0:0 -t 0:5:0 \
  *ac 4 -map_channel 0.0.0 -map_channel 0.0.1 -map_channel 0.0.4 -map_channel 0.0.5 output.wav -y
</code>

The resulting file ‘output.wav’ will be a multichannel wav with the
following channel order:

  * front left
  * front right
  * rear left
  * rear right

When loaded into audacity, and then when exported into either .WAV or .FLAC move
the channel slider to 6 channels and the following channel mix must be done:

  * output 1 -> channel: 1
  * output 2 -> channel: 2
  * output 3 -> channel: 5
  * output 4 -> channel: 6