pthdnvr wrote:I need to create a file in u-law mono wav, 8000 Hz, 64 kbps for a telephony application.
I've tried some of the files attached in this thread but was not successful.
I've also tried to export from Audacity 2.0.2 in other uncompressed files with options set to, and project rate set to 8000 Hz.
Test 1: wav (microsoft) header and U-law encoding
Test 2: wav (Nist Sphere) header and U-law encoding
Test 3: RAW (headerless) with u-law encoding.
None were able to play. I have not tried command with SOX since I need to hand this over to other people to do on a dynamic basic (changing broadcast messages). I am however able to use GoldWave (software) to convert an audacity created wav-16 bit pcm file into the u-law mono, 8KHz, 64 kps (there's a option for this in Goldwave) and the file works when converted with GoldWave. I'd like to do this with Audacity.
Are you exporting a mono or stereo file from Audacity? The file should be mono.
The only difference I can see in the headers between the Goldwave export and the Audacity export is that the Goldwave export puts the FACT chunk right at the end of the file after the audio data. As far as I am aware this is not standard.
- an unmodified Audacity-exported 8000 Hz 8-bit U-Law-encoded WAV file (the FACT chunk is before the audio data as normal)
- the same Audacity-exported 8000 Hz 8-bit U-Law-encoded WAV file but modified so that the FACT chunk is moved to the end of the file
- the same Audacity-exported 8000 Hz 8-bit U-Law-encoded WAV file but with the FACT chunk duplicated at the end of the file.
I don't think I would recommend Audacity exporting a file with the FACT chunk at the end in case some applications did not like it, but a duplicated FACT chunk might be OK.
Which of files a, b and c play in your application?
To make these sort of changes yourself, you can use a hex editor.