readaudio.c

在linux下多媒体开发实例linux下多媒体开发

/*
 * readaudio.c
 * Example program to read digital audio data from CD
 *
 * usage: readaudio <min> <sec> <frame> <# frames> <device>
 *   e.g. readaudio 1 2 3 4 /dev/cdrom
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <linux/cdrom.h>
#include <linux/sbpcd.h>

int main(int argc, char *argv[])
{
  int fd;                             /* CD-ROM file descriptor */
  int status;                         /* hold status of system calls */
  struct cdrom_read_audio read_audio; /* parameter for ioctl call */
  unsigned char *buffer;              /* buffer for audio data */
  int i;                              /* loop index */
  int minute, second, frame;          /* where to start reading */
  int nframes;                        /* number of frames to read */
  char *device;                       /* CD-ROM device name */

  /* check and parse command line arguments */
  if (argc != 6) {
    fprintf(stderr,
	   "usage: readaudio <min> <sec> <frame> <# frames> <device>\n"
	   "  e.g. readaudio 1 2 3 4 /dev/cdrom\n");
    exit(1);
  }
  minute  = strtol(argv[1], 0, 10);
  second  = strtol(argv[2], 0, 10);
  frame   = strtol(argv[3], 0, 10);
  nframes = strtol(argv[4], 0, 10);
  device  = argv[5];
  /* open device */  
  status = fd = open(device, O_RDONLY);
  if (status < 0) {
    perror("open failed");
    exit(1);
  }
  /* set audio buffer size - only needed for SBPCD drives */
  status = ioctl(fd, CDROMAUDIOBUFSIZ, nframes);
  if (status <= 0) {
    perror("CDROMAUDIOBUFSIZ ioctl failed (ignore for non-SBPCD drives)");
    /* don't exit, in case it is a non-SBPCD drive */
  }
  /* dynamically allocate buffer for audio data */
  buffer = (unsigned char*) malloc(CD_FRAMESIZE_RAW * nframes);
  if (buffer == 0) {
    perror("malloc failed");
    exit(1);
  }
  read_audio.addr_format = CDROM_MSF; /* use MSF format */
  read_audio.addr.msf.minute = minute;
  read_audio.addr.msf.second = second;
  read_audio.addr.msf.frame  = frame;
  read_audio.nframes = nframes;
  read_audio.buf = buffer;
  printf("Reading %d frames from %s starting from %02d:%02d.%03d (%d bytes)\n",
	 nframes, device, minute, second, frame, CD_FRAMESIZE_RAW * nframes);
  status = ioctl(fd, CDROMREADAUDIO, &read_audio);
  if (status != 0) {
    perror("CDROMREADAUDIO ioctl failed");
    exit(1);
  }
  /* display data in hex, 24 bytes per line */
  for (i = 0 ; i < CD_FRAMESIZE_RAW * nframes ; i++) {
    printf("%02X ", buffer[i]);
    if ((i+1) % 24 == 0)
      printf("\n");
  }
  exit(0);
}