Question

这个程序在Ubuntu中运行良好，但在Raspberry Pi上有段错误。编译期间也没有错误。我正在播放音乐，歌曲在Ubuntu中正常运行。

#include <stdio.h>
#include <stdlib.h>
#include <alsa/asoundlib.h>
#define PB_DEVICE ("plughw:0,0")
#define SAMPLING_RATE (48000)

int main (int argc, char *argv[])
{
   FILE *fp;
   int err;
   short buf[10],aud[10];
   snd_pcm_t *playback_handle;
   snd_pcm_hw_params_t *hw_params;
   char *pdevice=PB_DEVICE;
   int val=48000;
   int read_len = 0;

   fp=fopen("../inc/test2.wav","rb");
   if(NULL == fp)
   {
      printf("File Open Failed:\n");
   }

   if ((err = snd_pcm_open(&playback_handle, pdevice, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
      fprintf (stderr, "cannot open audio device %s (%s)\n", 
               pdevice,
               snd_strerror (err));
      exit (1);
   }
   if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
      fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   if ((err = snd_pcm_hw_params_any (playback_handle, hw_params)) < 0) {
      fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   if ((err = snd_pcm_hw_params_set_access (playback_handle, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
      fprintf (stderr, "cannot set access type (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   if ((err = snd_pcm_hw_params_set_format (playback_handle, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
      fprintf (stderr, "cannot set sample format (%s)\n",
               snd_strerror (err));
      exit (1);
   }
   if ((err = snd_pcm_hw_params_set_rate_near (playback_handle, hw_params,&val,0)) < 0) {
      fprintf (stderr, "cannot set sample rate (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   if ((err = snd_pcm_hw_params_set_channels (playback_handle, hw_params, 1)) < 0) {
      fprintf (stderr, "cannot set channel count (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   if ((err = snd_pcm_hw_params (playback_handle, hw_params)) < 0) {
      fprintf (stderr, "cannot set parameters (%s)\n",
               snd_strerror (err));
      exit (1);
   }

   snd_pcm_hw_params_free (hw_params);

   if ((err = snd_pcm_prepare (playback_handle)) < 0) {
      fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
               snd_strerror (err));
      exit (1);
   }
   while((read_len = fread(buf,2,sizeof(aud),fp)) > 0)
   {

      if((err = snd_pcm_writei(playback_handle, buf, read_len)) != read_len)
      {
         fprintf (stderr, "write to audio interface failed ReadLen [ %d ] (%s)\n",
                  read_len,
                  snd_strerror (err));
         exit (1);
      }
      read_len=0;
   }

   snd_pcm_close (playback_handle);
   exit (0);
   fclose(fp);
}

Answer 1

您误解了sizeof的作用，因此读取的数据量是缓冲区可以包含的两倍。根据实现细节，这可能会也可能不会导致内存保护错误或程序失败。

while((read_len = fread(buf,2,sizeof(aud),fp)) > 0)

尝试在程序的早期添加此行，您将了解您的问题：

printf("sizeof(aud)=%d\n", sizeof(aud));

sizeof返回 bytes 中的大小，但您尝试将其用作元素的计数，因为您尝试的每个元素都是2个字节告诉它每个读取20个2字节的项目，而不是每个2个字节的10个项目。

在Raspberry Pi上使用Alsa进行Seg故障

1 个答案: