iphone- [AVAssetReaderAudioMixOutput copyNextSampleBuffer] 错误

Question

我正在与 AVAssetReader 和 AVAssetWriter 合作制作多轨电影。所以我使用 [AVAssetReaderAudioMixOutput copyNextSampleBuffer] 和 [AVAssetWriterInput appendSampleBuffer] 完成了它。

但我不断收到错误:[AVAssetReaderTrackOutput copyNextSampleBuffer] 无法复制下一个示例缓冲区，除非 Assets 读取器处于“读取”状态。如何解决这个问题。

Answer 1

MPMediaQuery *meidaQuery = [[[MPMediaQuery alloc] init] autorelease];
MPMediaItem *mediaItem = [[meidaQuery items] objectAtIndex:0];
AVURLAsset *urlAsset = [AVURLAsset URLAssetWithURL:[mediaItem valueForProperty:MPMediaItemPropertyAssetURL] options:nil];

AVAssetReader *assetReader = [AVAssetReader assetReaderWithAsset:urlAsset error:nil];
AVAssetTrack *assetTrack = [[urlAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
AVAssetReaderTrackOutput *assetReaderTrackOutput = [AVAssetReaderTrackOutput assetReaderTrackOutputWithTrack:assetTrack outputSettings:NULL];
[assetReader addOutput:assetReaderTrackOutput];
[assetReader startReading];

CMSampleBufferRef sampleBufferRef = [assetReaderTrackOutput copyNextSampleBuffer];