如何通过一个无限循环改变audiotrack的持续时间？ [英] How to change the duration of the audiotrack by an infinite loop?

问题描述

如何通过一个无限循环改变audiotrack的持续时间

我知道我必须在 audioTrack.play应用以下行（）：

  audioTrack.setLoopPoints（0，generatedSnd.length，-1）;
 

例如，我想时间会半秒，因此，持续时间类型的变量INT是无效的。
要做到这一点我想要的声音反复播放和控制时间停止了定时器。

在code是：

 私人INT持续时间= 1; //秒
    私人INT采样率= 44100;
    私人最终诠释NUMSAMPLES =持续时间*采样率;
    私人最终双样本[] =新的双[NUMSAMPLES]
    私人双freqOfTone = 261.626; //例如音符C（DO）是261.626Hz。
    私人最后一个字节generatedSnd [] =新的字节[2 * NUMSAMPLES]。最终线程线程=新主题（新的Runnable（）{
                    公共无效的run（）{
                        genTone（）;
                        handler.post（新的Runnable（）{                            公共无效的run（）{
                                播放声音（）;
                            }
                        }）;
                    }
                }）;
                thread.start（）;
            }
        }）;
    无效genTone（）{
        的for（int i = 0; I＆LT; NUMSAMPLES ++我）{
            样本[I] = Math.sin（2 * Math.PI * I /（采样率/ freqOfTone））;
        }        //转换成16位PCM阵列声音
        //假设样品缓冲液是标准化。
        INT IDX = 0;
        对于（最终双DVAL：样品）{
            //规模最大振幅
            最终短VAL =（短）（（* DVAL 32767））;
            //在16位WAV PCM，第一个字节是低位字节
            generatedSnd [IDX +] =（字节）（VAL＆安培;设为0x00FF）;
            generatedSnd [IDX ++] =（字节）（（VAL＆放大器;为0xFF00）GT;＆GT;→8）;        }
    }    无效playSound（）{
        最后AudioTrack audioTrack =新AudioTrack（AudioManager.STREAM_MUSIC，
                采样率，AudioFormat.CHANNEL_OUT_MONO，
                AudioFormat.ENCODING_PCM_16BIT，generatedSnd.length，
                AudioTrack.MODE_STATIC）;
        audioTrack.write（generatedSnd，0，generatedSnd.length）;
        audioTrack.play（）;
    }
 

解决方案

对于我来说这一次的工作：

audioTrack.setLoopPoints（0，generatedSnd.length / FRAME_SIZE，-1）;

如果你正在玩的那么5.1系统帧大小，如果12（6 * 2），或7.1是16（8×2），支持立体声这是4。

How to change the duration of the audiotrack by an infinite loop?

I understand that I must apply the following line before audioTrack.play():

audioTrack.setLoopPoints (0, generatedSnd.length, -1);

For example, I want the duration will be half a second, therefore, the "duration" variable of type "int" isn't valid. To do so I want the sound to play repeatedly and control the time to stop with a Timer.

The code is:

  private int duration = 1; // seconds
    private int sampleRate = 44100; 
    private final int numSamples = duration * sampleRate;
    private final double sample[] = new double[numSamples];
    private double freqOfTone = 261.626; // For example musical note C (Do) is 261.626Hz.
    private final byte generatedSnd[] = new byte[2 * numSamples];

final Thread thread = new Thread(new Runnable() {
                    public void run() {
                        genTone();
                        handler.post(new Runnable() {

                            public void run() {
                                playSound();
                            }
                        });
                    }
                });
                thread.start();
            }
        });


    void genTone() {        
        for (int i = 0; i < numSamples; ++i) {
            sample[i] = Math.sin(2 * Math.PI * i / (sampleRate/freqOfTone));
        }

        // convert to 16 bit pcm sound array
        // assumes the sample buffer is normalised.
        int idx = 0;
        for (final double dVal : sample) {
            // scale to maximum amplitude
            final short val = (short) ((dVal * 32767));
            // in 16 bit wav PCM, first byte is the low order byte
            generatedSnd[idx++] = (byte) (val & 0x00ff);
            generatedSnd[idx++] = (byte) ((val & 0xff00) >>> 8);

        }
    }

    void playSound(){
        final AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC,
                sampleRate, AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT, generatedSnd.length,
                AudioTrack.MODE_STATIC);
        audioTrack.write(generatedSnd, 0, generatedSnd.length);
        audioTrack.play();
    }

解决方案

This one worked for me:

audioTrack.setLoopPoints(0, generatedSnd.length/FRAME_SIZE, -1);

if you are playing on 5.1 system then frame size if 12 (6*2), or for 7.1 it's 16 (8*2), for stereo it's 4.

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