I'm trying to figure out how to use libmad with C. The trouble is, libmad converts audio files to .pcm files and I'm unable to find a way to play these files. There is no straightforward .pcm player, and Audacity crashes every time I try to open the pcm file with it. Does any one have any experience with this? I'm open to converting these pcm files to wav files or some other format, but again there's no straightforward way to do this (at least I haven't found one).
Are you sure you're getting valid PCM data? What type of PCM are you getting?
Basic PCM is used on audio CDs and in WAV files ripped from CDs; it should be playable by just about anything. Specifically, it is 16-bit (per sample), 44.1 kHz (sample rate), stereo (2 channels). Playing this kind of PCM is as simple as
cat file.pcm > /dev/audio (or
/dev/dsp or another appropriate audio device).
The libmad homepage indicates that libmad may default to outputting 24-bit PCM, and your player software could be confused by it if expecting the standard 16-bit PCM. If you haven't already, check your program's libmad usage against the
madlld (libmad low-level API tutorial) to make sure you're getting the correct output from the library.
Since PCM data doesn't include headers like a WAV file does, you may need to specify the PCM format for a program to load the file correctly. Audacity should be able to handle any standard PCM format.
It's also possible you're getting invalid PCM output from
libmad, due to a bug in the library or due to improper use of the library by your code.
Tested on Ubuntu Linux 15.10:
sudo apt-get install ffmpeg ffplay -autoexit -f u16be -ar 44100 -ac 1 in.raw
sudo apt-get install play play -b 16 --endian big -e unsigned -r 44100 in.raw
-autoexit: exit player when stream ends
16: 16 bits per value
-ar: sample frequency
-ac: number of channels
play options: compare the values ;-)
Example of how to generate your own
.raw files to play with: https://stackoverflow.com/questions/732699/how-is-audio-represented-with-numbers/36510894#36510894
Perhaps you can use a tool like Sox
SoX is a cross-platform (Windows, Linux, MacOS X, etc.) command line utility that can convert various formats of computer audio files in to other formats. It can also apply various effects to these sound files, and, as an added bonus, SoX can play and record audio files on most platforms.