Question

我写了一个应用程序，它从硬件中播放声音（就像一个充满特定频率的正弦波的环形缓冲区）。一切正常，我可以正确播放创建的声音，除了定期点击（可能在缓冲区的末尾？）和噪音。

我初始化并运行Buffer：

void Audiooutput::InitializeAudioParameters()
{
    Audio_DataWritten = 0;
    Audio_fragments = 4;
    Audio_channels = 2;
    Audio_BufferSize = 256;
    Audio_Samplerate = 8000;
    Audio_ResamplingFactor = 1;
    Audio_Framesize = 2;
    // (SND_PCM_FORMAT_S16_LE / 8);
    Audio_frames = Audio_BufferSize / Audio_Framesize * Audio_fragments;

    snd_pcm_uframes_t size;
    err = snd_pcm_hw_params_any(pcmPlaybackHandle, hw_params);
    err = snd_pcm_hw_params_set_rate_resample(pcmPlaybackHandle, hw_params, 1);
    //     qDebug()<<a1.sprintf(" % d \t snd_pcm_hw_params_set_rate: %s",Audio_Samplerate,snd_strerror(err));
    err =
        snd_pcm_hw_params_set_format(pcmPlaybackHandle, hw_params,
                     SND_PCM_FORMAT_S16_LE);
    err =
        snd_pcm_hw_params_set_channels(pcmPlaybackHandle, hw_params,
                       Audio_channels);
    err = snd_pcm_hw_params_set_rate_near(pcmPlaybackHandle, hw_params, &Audio_Samplerate, 0);
    //     qDebug()<<a1.sprintf(" % d \t snd_pcm_hw_params_set_rate: %s",Audio_Samplerate,snd_strerror(err));

    if ((err =
         snd_pcm_hw_params_set_periods_near(pcmPlaybackHandle, hw_params,
                        &Audio_fragments, 0)) < 0) {
        qDebug() << a1.sprintf("Error setting # fragments to %d: %s\n",
                       Audio_fragments, snd_strerror(err));
    } else
        qDebug() << a1.sprintf("setting # fragments to %d: %s\n",
                       Audio_fragments, snd_strerror(err));
    err = snd_pcm_hw_params_get_buffer_size(hw_params, &size);
    if ((err =
         snd_pcm_hw_params_set_buffer_size_near(pcmPlaybackHandle,
                            hw_params,
                            &Audio_frames)) < 0) {
        qDebug() << a1.
            sprintf("Error setting buffer_size %d frames: %s",
                Audio_frames, snd_strerror(err));
    } else
        qDebug() << a1.sprintf("setting Buffersize to %d --> %d: %s\n",
                       Audio_BufferSize, Audio_frames,
                       snd_strerror(err));
    Audio_BufferSize = Audio_frames;
    if ((err = snd_pcm_hw_params(pcmPlaybackHandle, hw_params)) < 0) {
        qDebug() << a1.sprintf("Error setting HW params: %s",
                       snd_strerror(err));
    }
    Q_ASSERT(err >= 0);
}

void Audiooutput::ProduceAudioOutput(int n, int mmodes, int totalMModeGates,
         short *sinusValue, short *cosinusValue)
{
    for (int audioSample = 0; audioSample < n;
         audioSample += Audio_ResamplingFactor) {
        currentposition =
            (int)(m_Audio.generalPos % (Audio_BufferSize / 2));
        if (currentposition == 0) {
            QueueAudioBuffer();
            m_Audio.currentPos = 0;
        }
        m_Audio.generalPos++;
        AudioData[currentposition * 2] =
            (short)(sinusValue[audioSample]);
        AudioData[currentposition * 2 + 1] =
            (short)(cosinusValue[audioSample]);
    }
}

void Audiooutput::QueueAudioBuffer()
{
    snd_pcm_prepare(pcmPlaybackHandle);
    Audio_DataWritten +=
        snd_pcm_writei(pcmPlaybackHandle, AudioData, Audio_BufferSize);
}

更改音频缓冲区大小或片段也会更改单击时间段。任何人都可以帮我解决这个问题吗？我还检查了第一个和最后一个值。你总是与众不同。

操作系统：Ubuntu 11

更多细节。

接收数据的计数是动态的，并且变化取决于不同的参数。但我总是扮演某个角色，例如128个值或256或512 ....

//我从硬件（在Timerloop中）获取Audiodata

    audiobuffersize  = 256;
    short *AudioData = new short[256];
    int generalAudioSample = 0;

    void CollectDataFromHw()
{  
...  
        int n = 0;
        n = GetData(buf1,buf2);//buf1 = new short[MAX_SHRT]
        if(n > 0)
           FillAudioBuffer(n,buf1,buf2)
...
}
    -------------------------------------------
    void FillAudioBuffer(int n, short*buf1, short*buf2)
    {
      for(int audioSample = 0;audioSample < n; audioSample++){
         iCurrentAudioSample = (int)(generalAudioSample % (audiobuffersize/2)); 
         if(iCurrentAudioSample == 0)  {
            snd_pcm_writei(pcmPlaybackHandle,AudioData,audiobuffersize );
             memset(AudioData,0x00,audiobuffersize*sizeof(short));

         }
        generalAudioSample++;
        AudioData[iCurrentAudioSample * 2]   = (short)(buf1[audioSample];
        AudioData[iCurrentAudioSample * 2 +1]   = (short)(buf2[audioSample];

     }
    }

我也改变了audiobuffersize。如果我将它设置为更大的尺寸，我会点击一些Echo。

任何想法？ // ----------------------- 问题是

snd_pcm_prepare(pcmPlaybackHandle);

此功能的每次调用都会产生声音点击！

Answer 1

无法测试源代码，但我认为您听到的高频点击是声波中的不连续性。您必须确保循环周期（或缓冲区大小）是波周期的倍数。

检查缓冲区的第一个和最后一个值是否几乎相同（例如+/- 1）。它们的距离决定了不必要的咔嗒声的幅度。

Answer 2

解决在填充数据之前，缓冲区已经播放了好几次。

代码中的愚蠢错误。错误的parantez - ＆gt; audio_buffersize / 2＆lt; - - 因此，如果（iCurrentAudioSample == 0）真的!!!!!

，结果很常见

iCurrentAudioSample = (int)(generalAudioSample % (audio_buffersize/2));
if(iCurrentAudioSample == 0)
{
 writetoaudioStream(audiobuffer);
}

播放创建的音频数据有噪音和周期性的声音点击

操作系统：Ubuntu 11

2 个答案: