(Help) Converting recordings from GSM to MP3

I’m sorry to post something that has been posted a couple times before but none of those posts addressed my problem.

I’m simply trying to convert a GSM recording to MP3 and no matter what I do LAME creates a short blip of an audio file that is inaudible.

To keep things simple I’m starting with converting the wav to 44.1khz
Then I’m converting it to 2 channel (stereo)…so far so good. At this point I’ve confirmed that the audio is a CD quality file (16 bit, 44.1, ADPCM Wav) and sounds good. Then I run Lame and it always outputs the same thing. Even when I run a different recording, the output looks and sounds the same. The only suggestions I’ve seen on here was to run MLAME, but as I understand it, it just runs LAME anyway.

Here’s what I’m doing now:
sox greeting.gsm -r 44100 -a greeting.wav
sox greeting.wav -c2 greeting2.wav
all good so far…
lame -h greeting2.wav greeting2.mp3
lame -t -V7 greeting2.wav greeting3.mp3
lame -h -b 192 greeting2.wav greeting2.mp3
all produce the same short inaudible file. Everything on the screen indicates that there were no problems.

Any idea’s, suggestions?

I have seen something similar with an audio editor that was not able to correctly identify where the lame stuff was due to more than one version of lame on the same machine / change of location of lame.

Have you verified that your lame is able to convert any other well known wav to mp3?

No, I haven’t had it successfully convert a file. We have had success converting recordings generated using Monitor (as opposed to record) on another machine. I’ll try to convert one of those files…perhaps it’s just the local LAME install that’s the prob. Thanks for the suggestion.

gsm is a loss based codec. you will almost always experience a loss trying to convert it into other formats. This is why the AstLinux group took up contributions to get Allison Smith to record a bunch of sounds into .wav format so that they could be encoded into native phone formats (ulaw, g729 etc).

in the ‘oh by the way’ category… the man page of sox implies that it supports mp3s. The bundled sox with distributions in fact does not, but if you fetch the source or source rpm I bet you could rebuild it to support mp3’s, thus eliminating the need for Lame entirely.