AVAssetExportSession no audio (iPhone), works on iPad

We're trying to take an existing video with audio (.mov) and make a more email friendly version. Seems pretty straightforward and the code below does just what we need ... almost.

On an iPad2 (4.3.3) it works in debug & release builds all of the time. On the iPhone 4 (4.3.3) or 4th gen iPod Touch there's no audio. From time to time, no obvious correlation as to what triggers it, it will start working on the iPhone. Delete the app, rebuild/install, and it no longer works.

AVURLAsset* asset = [AVURLAsset URLAssetWithURL:[NSURL fileURLWithPath:sourcePath] options:nil]; session = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality]; session.outputURL = [NSURL fileURLWithPath:destPath]; session.outputFileType = AVFileTypeQuickTimeMovie; session.shouldOptimizeForNetworkUse = YES; [session exportAsynchronouslyWithCompletionHandler:^{ [self performSelectorOnMainThread:@selector(conversionFinished) withObject:nil waitUntilDone:NO]; }];


Are you playing the movie too, for example in an MPMoviePlayer? I have had some occasional export quirks while playing or using other initialized assets with the same URLs.


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