QNX的音频应用实例

来源：互联网发布：使用域名的好处编辑：程序博客网时间：2024/05/16 01:19

一.概述

QNX音频类似于linux，采用节点的方式，open,read,write

二.查看节点类型

ls -l /dev/snd/

结果：

-rw-rw-rw-   1 root      nto               0 Jan 01 00:07 controlC0-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 controlC1-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 controlC2lrw-rw-rw-   1 root      nto               0 Jan 01 00:55 defaultc -> pcmC0D0clrw-rw-rw-   1 root      nto               0 Jan 01  1970 defaultp -> pcmC0D1p-rw-rw-rw-   1 root      nto               0 Jan 01 00:07 mixerC0D0-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 mixerC1D0-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 mixerC2D0-rw-rw-rw-   1 root      nto               0 Jan 01 00:07 pcmC0D0c-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC0D0p-rw-rw-rw-   1 root      nto               0 Jan 01 00:07 pcmC0D1p-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC1D0c-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC1D0p-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC1D1p-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC2D0c-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC2D0p-rw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmC2D1plrw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmNavigation -> pcmC2D1plrw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmPreferredc -> pcmC0D0clrw-rw-rw-   1 root      nto               0 Jan 01 00:55 pcmPreferredp -> pcmC0D1p

C结尾的是capture的，P结尾是playback,另外C2D1是只card 2, device 1

三.sample code

<span style="white-space:pre"></span>snd_pcm_channel_info_tinfo;snd_pcm_channel_params_tparams;snd_pcm_channel_setup_tsetup;snd_pcm_t *pcmHandle;ret = snd_pcm_open(&pcmHandle, card,device, input ? SND_PCM_OPEN_CAPTURE : SND_PCM_OPEN_PLAYBACK);if(ret == EOK){printf("open success\n");}else{printf("open fault\n");}snd_pcm_plugin_set_disable( pcmHandle, PLUGIN_DISABLE_MMAP );memset( &info, 0, sizeof( info ) );info.channel = input ? SND_PCM_CHANNEL_CAPTURE : SND_PCM_CHANNEL_PLAYBACK;snd_pcm_plugin_info( pcmHandle, &info );memset( ¶ms, 0, sizeof( params ) );params.channel= info.channel;params.mode= SND_PCM_MODE_BLOCK;if( bits == 8 ){if( sign )params.format.format = SND_PCM_SFMT_S8;elseparams.format.format = SND_PCM_SFMT_U8;}else if( bits == 16 ){if( be && sign )params.format.format = SND_PCM_SFMT_S16_BE;else if( be )params.format.format = SND_PCM_SFMT_U16_BE;else if( sign )params.format.format = SND_PCM_SFMT_S16_LE;elseparams.format.format = SND_PCM_SFMT_U16_LE;}else if( bits == 24 ){if( be && sign )params.format.format = SND_PCM_SFMT_S24_BE;else if( be )params.format.format = SND_PCM_SFMT_U24_BE;else if( sign )params.format.format = SND_PCM_SFMT_S24_LE;elseparams.format.format = SND_PCM_SFMT_U24_LE;}params.format.interleave= 1;params.format.rate= rate;params.format.voices= 1;params.start_mode= SND_PCM_START_FULL;params.stop_mode= SND_PCM_STOP_ROLLOVER;if (input){params.buf.block.frag_size = params.format.rate * params.format.voices * sizeof(short) * 2 / 125;// Enforce 16ms frag size} else {params.buf.block.frag_size = info.max_fragment_size;}params.buf.block.frags_max= 2;params.buf.block.frags_min= 1;snd_pcm_plugin_params( pcmHandle, ¶ms );snd_pcm_plugin_prepare( pcmHandle, info.channel );memset( &setup, 0, sizeof( setup ) );setup.channel= info.channel;snd_pcm_plugin_setup( pcmHandle, &setup );

最后再执行read或者write动作

snd_pcm_plugin_read( arg->pcmHandleIn1, arg->audioBufferOut, arg->audioMaxLenOut );snd_pcm_plugin_write( arg->pcmHandleOut1, arg->audioBufferOut, arg->audioMaxLenOut);

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