unsigned int channels; /* channels */ snd_pcm_uframes_t period_size; /* period size */ unsigned int periods; /* periods */ snd_pcm_uframes_t buffer_size; /* buffer size */ snd_pcm_uframes_t min_align; /* Min alignment for the format */ size_t byte_align; unsigned int frame...
size_t byte_align; unsigned int frame_bits; unsigned int sample_bits; unsigned int info; unsigned int rate_num; unsigned int rate_den; unsigned int no_period_wakeup: 1; /* -- SW params -- */ int tstamp_mode; /* mmap timestamp is updated */ unsigned int period_step; snd_pcm_ufr...
(pcm, buffer, config.period_size); if (ret == -EPIPE) { // 播放被下溢中断,准备并重新开始 pcm_prepare(pcm); pcm_start(pcm); continue; } else if (ret < 0) { fprintf(stderr, "Error reading PCM: %s ", pcm_get_error(pcm)); break; } // 处理读取到的数据(例如,将其写入...
*pcm); int pcm_wait(struct pcm *pcm, int timeout); int pcm_set_avail_min(struct pcm *pcm, int avail_min); 对于pcm设备的操作只需要注意所操作的设备是否存在,以及设备的能力问题不要设置设备所不能及的能力设备就可以正常工作了,其实就是需要注意channels、rate、format、period_size和period_count。
{ struct pcm_config config; struct pcm *pcm; audio_t *c; if (cfg->bits != 16 && cfg->bits != 24 && cfg->bits != 32) { errno = EINVAL; return NULL; } config.channels = cfg->channels; config.rate = cfg->rate; config.period_size = 1024; config.period_count = 4; config....
/*rate in Hz*/19unsignedintchannels;/*channels*/20snd_pcm_uframes_t period_size;/*period size*/21unsignedintperiods;/*periods*/22snd_pcm_uframes_t buffer_size;/*buffer size*/23snd_pcm_uframes_t min_align;/*Min alignment for the format*/24size_t byte_align;25unsignedintframe_bits;...
SNDRV_PCM_HW_PARAM_PERIOD_SIZE:Approx frames between interrupts; SNDRV_PCM_HW_PARAM_PERIOD_BYTES:Approx bytes between interrupts; SNDRV_PCM_HW_PARAM_PERIODS:Approx interrupts per buffer; SNDRV_PCM_HW_PARAM_BUFFER_TIME:Approx duration of buffer in us; ...
config.period_size = 80; config.period_count = 4; config.format = PCM_FORMAT_S...
period */ snd_pcm_hw_params_get_period_size(params, &frames, &dir); size = frames * 4; /* 2 bytes/sample, 2 channels */ printf("size = %d\n",size); buffer = (char *) malloc(size); /* We want to loop for 5 seconds */ snd_pcm_hw_params_get_period_time(params, &val,...
The audio bus on this device is very flexible, including left or right-justified data options, support for I2S or PCM protocols, programmable data length options, a TDM mode for multichannel operation, very flexible master/slave configurability for each bus clock line, and the ability to ...