Newbie to audio programming; using PortAudio to decode Ogg

[Tatsh]

I am working on something part of a much larger project but to make things easier I want to make a simple CLI program that takes argv[1] and plays the file using PortAudio as the playback library and the necessary library to decode the file. In this case, it is Vorbis.

I have written the code as close to the PortAudio tutorials say to do so but I do not want to generate tones or anything, just play what is in the buffer until EOF of the Ogg file. I have no idea what to pass to PortAudio in order to make audio output. And I am very new to concepts like FIFO and ring buffer.

My current code for this app is here:

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#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <portaudio.h>
#include <vorbis/vorbisfile.h>

#define INPUTCHANNELS 0
#define BYTES_TO_READ 4096

typedef struct {
  struct OggVorbis_File file;
  struct vorbis_info *info;
  double length;
} oggStructure;

oggStructure data;

int oggCallback(const void *inputBuffer, void *outputBuffer,
                unsigned long framesPerBuffer,
                const PaStreamCallbackTimeInfo *timeInfo,
                const PaStreamCallbackFlags statusFlags, void *userData ) {
  oggStructure *data = (oggStructure*)userData;
  float *out = (float*)outputBuffer;
  unsigned long i;
  int finished = 0;
  (void)inputBuffer;
  
  for ( i = 0; i < framesPerBuffer; i++ ) {
    
  }
  
  return finished;
}

int main(int argc, char *argv[]) {
  if (argc != 2) {
    fprintf(stderr, "Usage: %s <ogg file>n", argv[0]);
    exit(EXIT_FAILURE);
  }
  
  FILE *ogg;
  bool streamFailure = false;
  char *buffer;
  int bitstream = 0;
  long bytesRead;
  
  PaError err; /* PortAudio types */
  PaStream *stream;
  
  if ((err = Pa_Initialize()) != paNoError) {
    fprintf(stderr, "Pa_Initialize() returned an error: %sn", Pa_GetErrorText(err));
    exit(EXIT_FAILURE);
  }
  
  ogg = fopen(argv[1], "rb");
  if (ov_open(ogg, &data.file, NULL, 0) < 0) {
    fprintf(stderr, "Error decoding %s.n", argv[1]);
    exit(EXIT_FAILURE);
  }
  
  data.info = ov_info(&data.file, -1);  /* Information about Ogg file */
  data.length = ov_time_total(&data.file, -1);
  
#ifdef __DEBUG__
  fprintf(stdout, "Ogg filename: %sn", argv[1]);
  fprintf(stdout, "Sample rate: %ldn", data.info->rate);
  fprintf(stdout, "Number of channels: %dn", data.info->channels);
  fprintf(stdout, "Lenght: %f secondsn", data.length);
#endif

  ov_pcm_seek(&data.file, 0);
#ifdef __DEBUG__
  fprintf(stdout, "Seeked file to position 0.n");
#endif
  
  while (bytesRead != 0 && bitstream == 0) {
    bytesRead = ov_read(&data.file, buffer, BYTES_TO_READ, 0, 2, 1, &bitstream);
    
    if (bytesRead < 0) {
      fprintf(stderr, "Error reading file.n");
      break;
    }
    
  }
  
  err = Pa_OpenDefaultStream(&stream, INPUTCHANNELS, data.info->channels, paFloat32, data.info->rate, BYTES_TO_READ, oggCallback, &data);
  if (err != paNoError) {
    fprintf(stderr, "Pa_OpenDefaultStream() returned an error: %sn", Pa_GetErrorText(err));
    streamFailure = true;
  }
  
  ov_clear(&data.file);
  
  if (streamFailure)
    exit(EXIT_FAILURE);

  exit(EXIT_SUCCESS);
}

If you use gcc, you can compile with:

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gcc -g -D__DEBUG__ -o portogg -Wall -ansi -lvorbisfile -lportaudio portogg.c

or similar.

Any help would be appreciated greatly.

[avee12]

Hi Tatsh,

I'm facing the same problem....

Can you please suggest me what solution did you found?
Can you please provide a code snippet/sample application for the same.

Thank you.