Powerful tape conversion tools using SoX, LAME and Bash Scripting

SoX running in the MacOS X Leopard Terminal.app

One of our recent and ongoing jobs is a very large, over 2000, NAB 10.5 inch reel to reel archive of quarter inch professional tape recordings.

To fit into the budget but maintain quality we needed to find a way to streamline our workflow in converting the high resolution 24 bit 96 Khz master .wav  files to CD quality (16 bit / 44 Khz) and MP3 (320 kbps) audio files.

Typically this would be done manually with 2 track audio software such as Audacity, Peak Audio Tools, Wavelab, etc with a Graphic User Interface (GUI). For such a large amount of individual files this is time consuming, expensive and unnecessary. While many audio editors have batch processing tools, Amadeus Pro being one of our favourites, they are still not as flexible as combining command line tools with a Bash script.

SoX is a powerful command line audio tool that can be used to edit, convert, process, record and play a wide range of digital audio files. It also has a very high quality resampling algorithm which we are using here.

Once the tape reels have been digitised they are split into individual .wav files which are then renamed with artist and track details using a php script that accesses a .csv file. These 24/96 resolution files are then converted to lower, CD resolution using SoX and to 320 kb/s MP3’s using LAME. The script also uses sed, the stream editor, to add the text _16_44.wav or _mp3.mp3 to the filename for ease of identification. The script finds all files with the suffix _24_96.wav in all the subdirectories of it’s working directory and processes these.

At the moment this script is running under Mac OS X 10.5.8 using the MacPorts project but will, in time, be moved to one of our Apple G4 servers running the PowerPC version of Debian GNU/Linux 5.05 ‘Lenny’.

1 comment

Good work dude linux is a very open system perfect for preservation and ypu moght want to lok for og vorbis format kt is open source audio co presion as god as if not better than mp3.

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