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)val)!= NULL) { printf(" %s (%s)\n", snd_pcm_format_name((snd_pcm_format_t)val), snd_pcm_forma...
1, open, 这个和 oss 相同,对应于 alsa 就是 snd_pcm_open ; 2, param 设置,这个就是 snd_pcm_hw_params; 3, 上层的 alsa 在设置 param 的成功以后或者出错的时候恢复都需要调用 snd_pcm_prepare; 4, write 函数; 现在一个个的来看; 4.1.1 open 过程介绍 如下图所示: 就是我先前说的分成三部分,...
==> 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_stream_name((snd_pcm_stream_t)val)); 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"); ...
==> 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 ==> soc_pcm_open ...
snd_pcm_open_noupdate(pcmp, root, str, stream, mode,hop + 1); else snd_pcm_open_conf(pcmp, name, root, pcm_conf, stream, mode);//单独分析1 //此函数将在配置树中查找对应的结点,然后将查找到的结点复制一份到pcm_conf中 snd_config_search_definition(root, "pcm", name, &pcm_conf);...
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 ...
alsa声卡/dev/snd/pcmC0D0p的open打开流程原文地址:/space.php?uid=20564848&do=blog&cuid=2116725aplay.c= main= snd_pcm_open(&handle, pcm_name, stream, open_mode); / 打开一路pcm,刷新config配置如果是default,同时type等于SND_CONFIG_TYPE_COMPOUND那么这里对应emptystatic const char *const build_in...