Hi,

I am new to ALSA and trying to play a wav file through ALSA by referring the sample code. It is a stereo, 44100Hz, 16 bit little endian file.

It is not properly playing the file. I suspect that the frames parameter might be wrong.

Below is the source code. Could any one give pointers on this.

long loops; int rc; int size; snd_pcm_t *handle; snd_pcm_hw_params_t *params; unsigned int val; int dir; snd_pcm_uframes_t frames; char *buffer;

/* Open PCM device for playback. */ rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0); if (rc < 0) { fprintf(stderr, "unable to open pcm device: %s\n", snd_strerror(rc)); exit(1); }

/* Allocate a hardware parameters object. */ snd_pcm_hw_params_alloca(&params);

/* Fill it in with default values. */ snd_pcm_hw_params_any(handle, params);

/* Set the desired hardware parameters. */

/* Interleaved mode */ snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);

/* Signed 16-bit little-endian format */ snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);

/* Two channels (stereo) */ snd_pcm_hw_params_set_channels(handle, params, 2);

/* 44100 bits/second sampling rate (CD quality) */ val = 44100; snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);

/* Set period size to 32 frames. */ frames = 44100; snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);

/* Write the parameters to the driver */ rc = snd_pcm_hw_params(handle, params); if (rc < 0) { fprintf(stderr, "unable to set hw parameters: %s\n", snd_strerror(rc)); exit(1); }

/* Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(params, &frames, &dir); printf("get period_size: %d\n",frames); size = frames * 4 ; /* 2 bytes/sample, 2 channels */ printf("Size:%d\n",size); buffer = (char *) malloc(size);

/* We want to loop for 2 seconds */ snd_pcm_hw_params_get_period_time(params, &val, &dir); printf("period time: %d\n",val); /* 2 seconds in microseconds divided by * period time */ loops = 3000000 / val; printf("loops: %d\n",loops);

FILE *fp; int file;

fp = fopen("ring-1.wav", "rb"); if (!fp) { printf("file open failure\n"); return NULL; } printf("file open success\n");

while (loops > 0) { loops--; //rc = read(0, buffer, size); rc = fread(buffer, sizeof(unsigned char), frames, fp); printf("bytes read: %d\n", rc); if (rc == 0) { printf("end of file on input\n"); break; } else if (rc != size) { fprintf(stderr, "short read: read %d bytes\n", rc); } rc = snd_pcm_writei(handle, buffer, frames); if (rc == -EPIPE) { /* EPIPE means underrun */ fprintf(stderr, "underrun occurred\n"); snd_pcm_prepare(handle); } else if (rc < 0) { fprintf(stderr, "error from writei: %s\n", snd_strerror(rc)); } else if (rc != (int)frames) { fprintf(stderr, "short write, write %d frames\n", rc); } }

snd_pcm_drain(handle); snd_pcm_close(handle); free(buffer); fclose(fp); return 0; }

Thanks & Regards, Thilaga