snd_pcm_open("default", SND_PCM_STREAM_PLAYBACK) // alsa-lib 接口open("/dev/snd/controlC0") // 打开控制设备; 主设备 116, 次设备 0open("/dev/snd/pcmC0D0p") // 打开PCM设备; 主设备 116, 次设备 16snd_open() // 根据主设备号找到该入口snd_minors[minor] // 根据次...
snd_card_create snd_ctl_create snd_ctl_dev_register创建"controlC%i"声卡对应的控制节点, 他的fops为snd_ctl_f_ops 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...
OPEN → SETUP → PREPARED → RUNNING → (XRUN/DRAINING/PAUSED/SUSPENDED) → ... → DISCONNECTED 1. 常见问题 Q1: 如何检测并处理XRUN状态? 调用snd_pcm_state()检查状态,若为XRUN,需恢复设备: AI检测代码解析 if (snd_pcm_state(pcm_handle) == SND_PCM_STATE_XRUN) { snd_pcm_prepare(pcm_ha...
snd_card_create snd_ctl_create snd_ctl_dev_register创建"controlC%i"声卡对应的控制节点, 他的fops为snd_ctl_f_ops 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_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 _snd_pcm_plug_open _snd_pcm_softvol_open _snd...
==> 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 _snd_pcm_plug_open _snd_pcm_softvol_open _snd...
snd_pcm_open是Alsa库提供的打开设备调用函数,这里我们指定打开缺省的音频设备,并根据参数mode将设备置为录音或是播放状态,如果设备打开成功,pcm_handle便指向该设备句柄,我们用全局变量保存起来,方便以后使用。 第二步是设置参数,参数设置不当将会导致音频设备无法正常工作。在设置参数前,我们需要了解一下各个参数的含...
snd_pcm_t*handle; snd_pcm_hw_params_t*params; unsignedintval;intdir; 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_strerro...
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 ==> snd_pcm_open_file或者oss的snd_pcm_oss_open_file ==> snd_pcm_open_substream ...
==> 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 _snd_pcm_plug_open _snd_pcm_softvol_open _snd...