snd_pcm_dev_register snd_register_device_for_dev 创建"pcmC%iD%ip"或者"pcmC%iD%ic"设备节点,它的fops为snd_pcm_f_ops[2] snd_pcm_f_ops[2] ==> snd_pcm_playback_open或者snd_pcm_capture_open ==> snd_pcm_open或者oss的snd_pcm_oss_f_reg.snd_pcm_oss_open,这就对应/dev/dsp了 ==> ...
stream SND_PCM_STREAM_PLAYBACK 或 SND_PCM_STREAM_CAPTURE,分别表示播放和录音的PCM流 mode 打开pcm句柄时的一些附加参数 SND_PCM_NONBLOCK 非阻塞打开(默认阻塞打开), SND_PCM_ASYNC 异步模式打开 返回值 0 表示打开成功,负数表示失败,对应错误码 */ if((err=snd_pcm_open(&handle,"default",type,0))<0...
/* Open PCM device for playback */ rc = snd_pcm_open(&handle,"default", SND_PCM_STREAM_PLAYBACK, 0); if (rc < 0) { printf("unable to open pcm device\n"); } /* Allocate a hardware parameters object */ snd_pcm_hw_params_alloca(¶ms); /* Fill it in with default values....
printf("\nPCM access types:\n");for(val =0; val <= SND_PCM_ACCESS_LAST; val++) { printf("%s\n", snd_pcm_access_name((snd_pcm_access_t)val)); } printf("\nPCM formats:\n");for(val =0; val <= SND_PCM_FORMAT_LAST; val++) {if(snd_pcm_format_name((snd_pcm_format_t)...
int snd_pcm_new(struct snd_card *card, const char *id, int device, int playback_count, int capture_count, struct snd_pcm ** rpcm); 1. 2. 参数device表示目前创建的是该声卡下的第几个pcm,第一个pcm设备从0开始。 参数playback_count表示该pcm将会有几个playback substream。
_snd_pcm_empty_open和snd_pcm_open_named_slave ==> snd_pcm_open_conf(pcmp, name, root, conf, stream, mode); ==> open_func = snd_dlobj_cache_lookup(open_name);将获得lib库中_snd_pcm_empty_open函数 所以open_func将等于_snd_pcm_empty_open _snd_pcm_empty_open _snd_pcm_asym_open ...
根据ALSA邮件列表中的建议，我尝试使用default:CARD=x作为snd_pcm_open函数的设备名称参数来打开默认设备...
_snd_pcm_empty_open和snd_pcm_open_named_slave ==> snd_pcm_open_conf(pcmp, name, root, conf, stream, mode); ==> open_func = snd_dlobj_cache_lookup(open_name);将获得lib库中_snd_pcm_empty_open函数 所以open_func将等于_snd_pcm_empty_open _snd_pcm_empty_open _snd_pcm_asym_open ...
alsa声卡/dev/snd/pcmC0D0p的open打开流程 soc_probe ==> snd_soc_register_card或者snd_soc_register_dai或者snd_soc_register_platform或者snd_soc_register_codec ==> snd_soc_instantiate_cards ==> snd_soc_instantiate_card ==> codec_dev->probe ...
for (val =0; val<= SND_PCM_STREAM_LAST; val++) printf(" %s\n", snd_pcm_stream_name((snd_pcm_stream_t)val)); printf("\nPCM access types:\n"); for (val =0; val<= SND_PCM_ACCESS_LAST; val++) { printf(" %s\n",