Question

I’m looking for a lightweight way to make my program (written in C) be able to play audio files on either windows or linux. I am currently using windows native calls, which is essentially just a single call that is passed a filename. I would like something similar that works on linux.

The audio files are Microsoft PCM, Single channel, 22Khz

Any Suggestions?

Answer 1

Since I’m also looking for an answer for question I did a bit of research, and I haven’t find any simple (simple like calling one function) way to play an audio file. But with some lines of code, it is possible even in a portable way using the already mentioned portaudio and libsndfile (LGPL).

Here is a small test case I’ve written to test both libs:

 #include <portaudio.h> #include <sndfile.h>  static int output_cb(const void * input, void * output, unsigned long frames_per_buffer,         const PaStreamCallbackTimeInfo *time_info,         PaStreamCallbackFlags flags, void * data) {     SNDFILE * file = data;      /* this should not actually be done inside of the stream callback      * but in an own working thread       *      * Note although I haven't tested it for stereo I think you have      * to multiply frames_per_buffer with the channel count i.e. 2 for      * stereo */     sf_read_short(file, output, frames_per_buffer);     return paContinue; }  static void end_cb(void * data) {     printf('end!\n'); }  #define error_check(err) \     do {\         if (err) { \             fprintf(stderr, 'line %d ', __LINE__); \             fprintf(stderr, 'error number: %d\n', err); \             fprintf(stderr, '\n\t%s\n\n', Pa_GetErrorText(err)); \             return err; \         } \     } while (0)  int main(int argc, char ** argv) {     PaStreamParameters out_param;     PaStream * stream;     PaError err;     SNDFILE * file;     SF_INFO sfinfo;      if (argc < 2)     {         fprintf(stderr, 'Usage %s \n', argv[0]);         return 1;     }      file = sf_open(argv[1], SFM_READ, &sfinfo);     printf('%d frames %d samplerate %d channels\n', (int)sfinfo.frames,             sfinfo.samplerate, sfinfo.channels);      /* init portaudio */     err = Pa_Initialize();     error_check(err);      /* we are using the default device */     out_param.device = Pa_GetDefaultOutputDevice();     if (out_param.device == paNoDevice)     {         fprintf(stderr, 'Haven't found an audio device!\n');         return -1;     }      /* stero or mono */     out_param.channelCount = sfinfo.channels;     out_param.sampleFormat = paInt16;     out_param.suggestedLatency = Pa_GetDeviceInfo(out_param.device)->defaultLowOutputLatency;     out_param.hostApiSpecificStreamInfo = NULL;      err = Pa_OpenStream(&stream, NULL, &out_param, sfinfo.samplerate,             paFramesPerBufferUnspecified, paClipOff,             output_cb, file);     error_check(err);      err = Pa_SetStreamFinishedCallback(stream, &end_cb);     error_check(err);      err = Pa_StartStream(stream);     error_check(err);      printf('Play for 5 seconds.\n');     Pa_Sleep(5000);      err = Pa_StopStream(stream);     error_check(err);      err = Pa_CloseStream(stream);     error_check(err);      sf_close(file);      Pa_Terminate();      return 0; } 

Some notes to the example. It is not good practice to do the data loading inside of the stream callback, but inside an own loading thread. If you need to play several audio files it becomes even more difficult, because not all portaudio backends support multiple streams for one device, for example the OSS backend doesn’t, but the ALSA backend does. I don’t know how the situation is on windows. Since all your input files are of the same type you could mix them on you own, which complicates the code a bit more, but then you’d have also support for OSS. If you would have also different sample rates or number of channels, it’d become very difficult.

So If you don’t want to play multiple files at the same time, this could be a solution or at least a start for you.