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Playing audio backwards

开发者 https://www.devze.com 2023-02-08 09:07 出处:网络
Hi I\'d like to play开发者_开发技巧 audio backwards in Android. How do I accomplish it? Any pointers will be appreciated. Thanks.there probably isn\'t a functionality in the apis for this.

Hi I'd like to play开发者_开发技巧 audio backwards in Android. How do I accomplish it? Any pointers will be appreciated. Thanks.


there probably isn't a functionality in the apis for this.

however, it's quite easy to play pcm audio data backwards.

a demonstration using c++ style pseudo-code:

/* assuming 1 channel (mono), 16 bit LPCM */
const int16_t* const audioFileBuffer = audioFile.audioBuffer();

/* forward */
for (int idx = 0, sampleCount = audioFile.sampleCount(); idx < sampleCount; ++idx) {
    outputBuffer[idx] = audioFileBuffer[idx];
}

/* reverse */
for (int idx = 0, sampleCount = audioFile.sampleCount(), read = audioFile.sampleCount() - 1; idx < sampleCount; ++idx, --read) {
    outputBuffer[idx] = audioFileBuffer[read];
}


I'm not sure if there is a native way to do it (I am still new to the Android development scene myself) but if it came down to it, you could always try decoding the file yourself in reverse rather than relying on the existing API.

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