awirtz
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SoX is a very useful command-line tool capable of converting between numerous audio file formats and applying a number of effects. I use it to downsample 48kHz/16bit/PCM Wav files into 8kHz/8bit/u-Law Wav files.
Versions are available for most modern operating systems from the following site:
http://sox.sf.net
(NB: SoX currently misinterprets volume adjustment values specified in dB. For some reason it is convinced that +6 dB == 200%. Easy enough to work around once you know it is there, but an odd quirk when unexpected. Just feed it twice the dB value you truly mean.)
The following example command line will take an input audio file (the format can be autodeteced for wav files, so there is no need to specify the input bitrate, etc.), resample the audio using a polyphase algorithm into 8Khz/8bit/mono/u-Law (much better than most other conversion techniques out there), adjust the gain level up by 5.5dB, and output it to another wav file:
sox original.wav -r8000 -b -c1 -U new.wav polyphase vol +11 dB |
awirtz
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Audacity is recording, mixing, and editing tool, with many of the same features as professional packages like CakeWalk or Digital Performer, but completely free and open-source.
Versions are available for Windows, Linux and Mac OS/X
http://audacity.sf.net |
PremiseScienceMuseum
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| Audacity is great for recording, editing, and mixing your files. Alas, it does not export u-Law encoded .wav files. You can only use the linear PCM ecoder. This causes lots of pops and clicks in the background of your file. You will need some sort of conversion utility to change your high quality wavs to the u-Law encoded 8bit wavs. |
