stream:指定流类型,SND_PCM_STREAM_PLAYBACK表示播放,SND_PCM_STREAM_CAPTURE则表示采集; mode:指定了open模式,通常情况下会将其设置为0,表示默认打开模式,使用阻塞方式打开设备;也可将其设置为SND_PCM_NONBLOCK,表示以非阻塞方式打开设备。 设备打开成功,返回0;打开失败,返回小于0的错误编号,可以使用alsa-lib提供的...
mode | (nonblock ? SND_PCM_NONBLOCK : 0), 0, sync_ptr_ioctl); ==> snd_ctl_hw_open filename等于"/dev/snd/controlC0" ==> snd_open_device(filename, fmode); ctl->ops = &snd_ctl_hw_ops; ctl->private_data = hw; ctl->poll_fd = fd; *handle = ctl; filename等于"/dev/snd/...
==> snd_pcm_hw_open(pcmp, name, card, device, subdevice, stream, mode | (nonblock ? SND_PCM_NONBLOCK : 0), 0, sync_ptr_ioctl); ==> snd_ctl_hw_open filename等于"/dev/snd/controlC0" ==> snd_open_device(filename, fmode); ctl->ops = &snd_ctl_hw_ops; ctl->private_data...
==> snd_pcm_hw_open(pcmp, name, card, device, subdevice, stream, mode | (nonblock ? SND_PCM_NONBLOCK : 0), 0, sync_ptr_ioctl); ==> snd_ctl_hw_open filename等于"/dev/snd/controlC0" ==> snd_open_device(filename, fmode); ctl->ops = &snd_ctl_hw_ops; ctl->private_data...
snd_pcm_hw_open主要完成如下工作:调用snd_ctl_hw_open创建了一个hw control设备,并设置回调const snd_ctl_ops_t *ops,回调参数为snd_ctl_hw_ops,具体操作接口如下:static const snd_ctl_ops_t snd_ctl_hw_ops = { .close = snd_ctl_hw_close, .nonblock = snd_ctl_hw_nonblock, .async = snd_...
pcmp 打开的pcm句柄 name 要打开的pcm设备名字,默认default,或者从asound.conf或者asoundrc里面选择所要打开的设备 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...
\n"); exit (-1 ); } /* Open PCM device for playback. */ ...
snd_pcm_hw_open主要完成如下工作: 调用snd_ctl_hw_open创建了一个hw control设备,并设置回调const snd_ctl_ops_t *ops,回调参数为snd_ctl_hw_ops,具体操作接口如下: static const snd_ctl_ops_t snd_ctl_hw_ops = { .close = snd_ctl_hw_close, .nonblock = snd_ctl_hw_nonblock, .async = snd...
==> snd_pcm_hw_open(pcmp, name, card, device, subdevice, stream, mode | (nonblock ? SND_PCM_NONBLOCK : 0), 0, sync_ptr_ioctl); ==> snd_ctl_hw_open filename等于"/dev/snd/controlC0" ==> snd_open_device(filename, fmode); ctl->ops = &snd_ctl_hw_ops; ctl->private_data...