Convert GSM6.10 to PCM with no data loss

Question

I have code that converts audio from PCM to GSM6.10 and back, using MSACM functions. When I run it to convert back and forth a few times, I get a noticeable degradation in audio quality.

I did similar conversions in Audacity, and saw a similar degradation.

Does anyone have a way to do this conversion without suffering audio degradation?

Answer 1

GSM 6.10 is a lossy audio encoding, each time you compress audio - you lose in quality. There is no way to compress with GSM 6.10 without quality loss. The best you can do is to compress into maximal bitrate so that you lose less in quality. Or, you need a lossless compression (not GSM 6.10) instead.