我在使用 AVAssetReader 时遇到问题,无法从 iPod 库获取样本并通过音频队列进行流式传输。我无法找到任何这样的示例,因此我尝试实现自己的示例,但似乎 AssetReader 在音频队列的回调函数处“搞砸了”。具体来说,当它执行 copyNextSampleBuffer 时,它会失败,即,当它尚未完成时,它会返回 null。我已经确保指针存在,因此如果有人可以提供帮助,那就太好了。
下面是我使用过的回调函数代码。当 AudioQueue 回调未调用此回调函数时,该函数会“起作用”。
static void HandleOutputBuffer (
void *playerStateH,
AudioQueueRef inAQ,
AudioQueueBufferRef inBuffer
) {
AQPlayerState *pplayerState = (AQPlayerState *) playerStateH;
//if (pplayerState->mIsRunning == 0) return;
UInt32 bytesToRead = pplayerState->bufferByteSize;
[[NSNotificationCenter defaultCenter] postNotificationName:NOTIF_callsample object:nil];
float * inData =(float *) inBuffer->mAudioData;
int offsetSample = 0;
//Loop until finish reading from the music data
while (bytesToRead) {
/*THIS IS THE PROBLEMATIC LINE*/
CMSampleBufferRef sampBuffer = [pplayerState->assetWrapper getNextSampleBuffer]; //the assetreader getting nextsample with copyNextSampleBuffer
if (sampBuffer == nil) {
NSLog(@"No more data to read from");
// NSLog(@"aro status after null %d",[pplayerState->ar status]);
AudioQueueStop (
pplayerState->mQueue,
false
);
pplayerState->mIsRunning = NO;
return;
}
AudioBufferList audioBufferList;
CMBlockBufferRef blockBuffer;
CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
AudioBuffer audioBuffer = audioBufferList.mBuffers[0];
memcpy(inData + (2*offsetSample),audioBuffer.mData,audioBuffer.mDataByteSize);
bytesToRead = bytesToRead - audioBuffer.mDataByteSize;
offsetSample = offsetSample + audioBuffer.mDataByteSize/8;
}
inBuffer->mAudioDataByteSize = offsetSample*8;
AudioQueueEnqueueBuffer (
pplayerState->mQueue,
inBuffer,
0,
0
);
}
我也遇到了同样令人困惑的错误。果然,“设置”音频会话使错误消失了。这就是我设置音频会话的方式。
- (void)setupAudio {
[[AVAudioSession sharedInstance] setDelegate:self];
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryAmbient error:nil];
NSError *activationError = nil;
[[AVAudioSession sharedInstance] setActive: YES error:&activationError];
NSLog(@"setupAudio ACTIVATION ERROR IS %@", activationError);
[[AVAudioSession sharedInstance] setPreferredIOBufferDuration:0.1 error:&activationError];
NSLog(@"setupAudio BUFFER DURATION ERROR IS %@", activationError);
}
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