StackOverflow2013

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POAVMutableAudioMix and AVAssetExportSession
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copied!<p>I want to make fade in/out effect for export session. But it doesn't work. Please help me!</p> <p>Trim works perfect! But fade in/out doesn't :(((</p> <pre><code> NSURL *assetURL = [song valueForProperty:MPMediaItemPropertyAssetURL]; AVURLAsset *songAsset = [AVURLAsset URLAssetWithURL:assetURL options:nil]; AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:songAsset presetName:AVAssetExportPresetPassthrough]; NSArray *tracks = [songAsset tracksWithMediaType:AVMediaTypeAudio]; AVAssetTrack *track = [tracks objectAtIndex:0]; id desc = [track.formatDescriptions objectAtIndex:0]; const AudioStreamBasicDescription *audioDesc = CMAudioFormatDescriptionGetStreamBasicDescription((CMAudioFormatDescriptionRef)desc); FourCharCode formatID = audioDesc->mFormatID; // trim track CMTime startTrimTime = CMTimeMakeWithSeconds(startTime, 1); CMTime endTrimTime = CMTimeMakeWithSeconds(endTime, 1); CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTrimTime, endTrimTime); exportSession.timeRange = exportTimeRange; //add fade in, fade out CMTime startFadeInTime = startTrimTime; CMTime endFadeInTime = CMTimeMakeWithSeconds(startTime + 4.0, 1); CMTimeRange fadeInTimeRange = CMTimeRangeFromTimeToTime(startFadeInTime, endFadeInTime); CMTime startFadeOutTime = CMTimeMakeWithSeconds(endTime - 4.0, 1); CMTime endFadeOutTime = endTrimTime; CMTimeRange fadeOutTimeRange = CMTimeRangeFromTimeToTime(startFadeOutTime, endFadeOutTime); AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix]; //AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParameters]; AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track]; [exportAudioMixInputParameters setVolumeRampFromStartVolume:0.0 toEndVolume:1.0 timeRange:fadeInTimeRange]; [exportAudioMixInputParameters setVolumeRampFromStartVolume:1.0 toEndVolume:0.0 timeRange:fadeOutTimeRange]; exportAudioMix.inputParameters = [NSArray arrayWithObject:exportAudioMixInputParameters]; exportSession.audioMix = exportAudioMix; ... myDeleteFile(filePath); exportSession.outputURL = [NSURL fileURLWithPath:filePath]; [exportSession exportAsynchronouslyWithCompletionHandler:^{ if (exportSession.status == AVAssetExportSessionStatusCompleted) { NSLog(@"export session completed"); // //return YES; } else { NSLog(@"export session error"); //return NO; } [exportSession release]; }]; </code></pre>

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