snd_pcm_hw_params_set_format() private method

private snd_pcm_hw_params_set_format ( IntPtr playback_handle, IntPtr hw_params, snd_pcm_format snd_pcm_format ) : int
playback_handle System.IntPtr
hw_params System.IntPtr
snd_pcm_format snd_pcm_format
return int
Alsa Class Documentation
示例#1
0
        //const int SndOutPacketSize = 512;
        //short[] Buffer = new short[2 * 1024];

        // Frame = 2 * sizeof(ushort)
        // Period = is the number of frames in between each hardware interrupt. The poll() will return once a period.
        // PeriodsPerBuffer
        public AudioAlsaImpl()
        {
            if (_playbackHandle != IntPtr.Zero)
            {
                return;
            }

            try
            {
                fixed(IntPtr *playbackHandlePtr = &_playbackHandle)
                fixed(IntPtr * hwParamsPtr = &_hwParams)
                {
                    var rate = SampleRate;

                    //int period_time = (SndOutPacketSize * 1000) / (SampleRate / 1000);
                    //int buffer_time = period_time * NumBuffers;

                    Assert("snd_pcm_open",
                           Alsa.snd_pcm_open(playbackHandlePtr, Device,
                                             Alsa.snd_pcm_stream_t.SND_PCM_LB_OPEN_PLAYBACK, 0));
                    Assert("snd_pcm_hw_params_malloc", Alsa.snd_pcm_hw_params_malloc(hwParamsPtr));
                    Assert("snd_pcm_hw_params_any", Alsa.snd_pcm_hw_params_any(_playbackHandle, _hwParams));
                    Assert("snd_pcm_hw_params_set_access",
                           Alsa.snd_pcm_hw_params_set_access(_playbackHandle, _hwParams,
                                                             Alsa.snd_pcm_access.SND_PCM_ACCESS_RW_INTERLEAVED));
                    Assert("snd_pcm_hw_params_set_format",
                           Alsa.snd_pcm_hw_params_set_format(_playbackHandle, _hwParams,
                                                             Alsa.snd_pcm_format.SND_PCM_FORMAT_S16_LE));
                    Assert("snd_pcm_hw_params_set_rate_near",
                           Alsa.snd_pcm_hw_params_set_rate_near(_playbackHandle, _hwParams, &rate, null));

                    //Assert("snd_pcm_hw_params_set_buffer_time_near", Alsa.snd_pcm_hw_params_set_buffer_time_near(playback_handle, hw_params, &buffer_time, null));
                    //Assert("snd_pcm_hw_params_set_period_time_near", Alsa.snd_pcm_hw_params_set_period_time_near(playback_handle, hw_params, &period_time, null));

                    Assert("snd_pcm_hw_params_set_channels",
                           Alsa.snd_pcm_hw_params_set_channels(_playbackHandle, _hwParams, Channels));

                    Assert("snd_pcm_hw_params_set_periods",
                           Alsa.snd_pcm_hw_params_set_periods(_playbackHandle, _hwParams, Periods, 0));
                    Assert("snd_pcm_hw_params_set_period_size",
                           Alsa.snd_pcm_hw_params_set_period_size(_playbackHandle, _hwParams, Periodsize, null));
                    Assert("snd_pcm_hw_params_set_buffer_size",
                           Alsa.snd_pcm_hw_params_set_buffer_size(_playbackHandle, _hwParams, 4 * Periodsize));

                    Assert("snd_pcm_hw_params", Alsa.snd_pcm_hw_params(_playbackHandle, _hwParams));
                    Assert("snd_pcm_hw_params_free", Alsa.snd_pcm_hw_params_free(_hwParams));
                }
            }
            catch (Exception exception)
            {
                Console.Error.WriteLine(exception);
            }

            //available_start = Alsa.snd_pcm_avail_update(playback_handle);
        }