alsa playback 問題

[stone886]

main (int argc, char *argv[])
{
   int i;
   int err;
   short buf[128];
   snd_pcm_t *playback_handle;
   snd_pcm_hw_params_t *hw_params;

   if ((err = snd_pcm_open (&playback_handle, argv[1], SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
      fprintf (stderr, "cannot open audio device %s (%s)\n", 
	    argv[1],
	    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, 44100, 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, 2)) < 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);
   }

   for (i = 0; i < 10; ++i) {
      if ((err = snd_pcm_writei (playback_handle, buf, 128)) != 128) {
	 fprintf (stderr, "write to audio interface failed (%s)\n",
	       snd_strerror (err));
	 exit (1);
      }
   }

   snd_pcm_close (playback_handle);
   exit (0);
}

set args default
用gdb trace 執行到snd_pcm_hw_params_set_rate_near 便錯誤Segmentation fault
這是什麼原因呢
thx

[xhy_851221]

[Quote=引用 1 楼 fetag 的回复:]
if ((err = snd_pcm_hw_params_set_rate_near (playback_handle, hw_params, 44100, 0)) < 0) {

先在這個之前打個斷點，然後查看各個引數的值是否合法
[/Quote]
up

[独孤过儿]

沒看出來有什麽問題啊，能把你在gdb裡面加載運行的命令抓來看下嗎？

[blackbillow]

src/pcm/pcm.c:4098:int snd_pcm_hw_params_set_rate_near(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int *val, int *dir)

这个函数的第三 四个参数都是指针

[独孤过儿]

if ((err = snd_pcm_hw_params_set_rate_near (playback_handle, hw_params, 44100, 0)) < 0) {

先在這個之前打個斷點，然後查看各個引數的值是否合法

[stone886]

(gdb) p playback_handle
$1 = (snd_pcm_t *) 0x805e490
(gdb) p hw_params
$5 = (snd_pcm_hw_params_t *) 0x805e058