I’m starting on a project to have a small microcontroller take 8 bit unsigned PCM data from FAT32 files on an SD card and send those audio samples to an onboard DAC, to be voiced out over a two-way radio system. Once I get that working I may want to try using uLaw PCM to gain a little bit better S/N. Since the radio link has limited bandwidth (3 kHz), the over-the-radio fidelity is not too important, instead intelligibility is of prime importance.
My plan is to record the voice phrases and words with good fidelity at 44100 using Audacity and then use the Macro feature to process the audio (convert stereo to mono, low pass filter at 2800 Hz, compress a little bit). All that I have working and it works well. My problem is that I don’t see a way to use Audacity Macros to convert the 41000 Hz samples to 8000 Hz samples, and then export those samples as 8 bit unsigned PCM. I assume that the rate change and the Macro export as 8 bit unsigned PCM are not supported by Audicity Macros. Is that correct?
I’ve looked at using ffmpeg to convert 44100Hz WAV to 8000 Hz PCM, but it appears to my untrained eye that that program does not support a change in audio rate.
Can anyone offer some suggestions as to how I can batch convert a couple of hundred audio files from 44100 WAV to 8000 unsigned 8 bit PCM? I know that I could do the original recording at 8000 Hz sampling, but I’d prefer that the original audio recordings be done with good fidelity (hence the 44100 Hz rate for the original recordings).