Save fade-in audio with setVolumeRampFromStartVolume not working in iOS

Question

I am trying to cut an audio file for an iPhone project. I can cut it and save it, but any disappearance / disappearance that I am trying to apply does not work, the sound file just remains, but does not fade.

I am using the following code:

// // NO PROBLEMS TO SEE HERE, MOVE ON // NSArray *documentsFolders = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); int currentFileNum = 10; NSURL *url = [NSURL fileURLWithPath: [[documentsFolders objectAtIndex:0] stringByAppendingPathComponent:[NSString stringWithFormat:@"%@%d.%@", AUDIO_SOURCE_FILE_NAME ,currentFileNum, AUDIO_SOURCE_FILE_EXTENSION ]]]; NSDictionary *options = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey]; AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:url options:options]; AVAssetExportSession* exporter = [AVAssetExportSession exportSessionWithAsset:asset presetName:AVAssetExportPresetAppleM4A]; for (NSString* filetype in exporter.supportedFileTypes) { if ([filetype isEqualToString:AVFileTypeAppleM4A]) { exporter.outputFileType = AVFileTypeAppleM4A; break; } } if (exporter.outputFileType == nil) { NSLog(@"Needed output file type not found? (%@)", AVFileTypeAppleM4A); //return; } NSString* outPath = [[documentsFolders objectAtIndex:0] stringByAppendingPathComponent:[NSString stringWithFormat:@"%@%d.%@", AUDIO_CUTTED_FILE_NAME ,currentFileNum, AUDIO_SOURCE_FILE_EXTENSION ]]; NSURL* const outUrl = [NSURL fileURLWithPath:outPath]; exporter.outputURL = outUrl; float endTrimTime = CMTimeGetSeconds(asset.duration); float startTrimTime = fminf(AUDIO_DURATION, endTrimTime); CMTime startTrimCMTime=CMTimeSubtract(asset.duration, CMTimeMake(startTrimTime, 1)); exporter.timeRange = CMTimeRangeMake(startTrimCMTime, asset.duration); // // TRYING TO APPLY FADEIN FADEOUT, NOT WORKING, NO RESULTS, "CODE IGNORED" // AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix]; NSMutableArray* inputParameters = [NSMutableArray arrayWithCapacity:1]; CMTime startFadeInTime = startTrimCMTime; CMTime endFadeInTime = CMTimeMake(startTrimTime+1, 1); CMTime startFadeOutTime = CMTimeMake(endTrimTime-1, 1); CMTime endFadeOutTime = CMTimeMake(endTrimTime, 1); CMTimeRange fadeInTimeRange = CMTimeRangeFromTimeToTime(startFadeInTime, endFadeInTime); CMTimeRange fadeOutTimeRange = CMTimeRangeFromTimeToTime(startFadeOutTime, endFadeOutTime); AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParameters]; [exportAudioMixInputParameters setVolume:0.0 atTime:CMTimeMakeWithSeconds(startTrimTime-0.01, 1)]; [exportAudioMixInputParameters setVolumeRampFromStartVolume:0.0 toEndVolume:1.0 timeRange:fadeInTimeRange]; [exportAudioMixInputParameters setVolumeRampFromStartVolume:1.0 toEndVolume:0.0 timeRange:fadeOutTimeRange]; [inputParameters insertObject:exportAudioMixInputParameters atIndex:0]; exportAudioMix.inputParameters = inputParameters; exporter.audioMix = exportAudioMix; [exporter exportAsynchronouslyWithCompletionHandler:^(void) { NSString* message; switch (exporter.status) { case AVAssetExportSessionStatusFailed: message = [NSString stringWithFormat:@"Export failed. Error: %@", exporter.error.description]; [asset release]; break; case AVAssetExportSessionStatusCompleted: { [asset release]; [self reallyConvert:currentFileNum]; message = [NSString stringWithFormat:@"Export completed: %@", outPath]; break; } case AVAssetExportSessionStatusCancelled: message = [NSString stringWithFormat:@"Export cancelled!"]; [asset release]; break; default: NSLog(@"Export 4 unhandled status: %d", exporter.status); [asset release]; break; } }]; 

Answer 1

You need to select a track. Instead of calling:

 AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParameters]; 

Call:

 AVAssetTrack *assetTrack = [[asset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0]; AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:assetTrack]; 

In the existing code, you can also specify the track as follows:

 exportAudioMixInputParameters.trackID = [[[asset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0] trackID]; 

Good luck

Answer 2

Here is the solution.

setVolumeRampFromStartVolume does not work.

 AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix]; AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:track]; 

// fade in

 [exportAudioMixInputParameters setVolume:0.0 atTime:CMTimeMakeWithSeconds(start-1, 1)]; [exportAudioMixInputParameters setVolume:0.1 atTime:CMTimeMakeWithSeconds(start, 1)]; [exportAudioMixInputParameters setVolume:0.5 atTime:CMTimeMakeWithSeconds(start+1, 1)]; [exportAudioMixInputParameters setVolume:1.0 atTime:CMTimeMakeWithSeconds(start+2, 1)]; 

// disappears

 [exportAudioMixInputParameters setVolume:1.0 atTime:CMTimeMakeWithSeconds((start+length-2), 1)]; [exportAudioMixInputParameters setVolume:0.5 atTime:CMTimeMakeWithSeconds((start+length-1), 1)]; [exportAudioMixInputParameters setVolume:0.1 atTime:CMTimeMakeWithSeconds((start+length), 1)]; exportAudioMix.inputParameters = [NSArray arrayWithObject:exportAudioMixInputParameters]; // configure export session output with all our parameters exportSession.outputURL = [NSURL fileURLWithPath:filePath]; // output path exportSession.outputFileType = AVFileTypeAppleM4A; // output file type exportSession.timeRange = exportTimeRange; // trim time ranges exportSession.audioMix = exportAudioMix; // fade in audio mix // perform the export [exportSession exportAsynchronouslyWithCompletionHandler:^{ if (AVAssetExportSessionStatusCompleted == exportSession.status) { NSLog(@"AVAssetExportSessionStatusCompleted"); } else if (AVAssetExportSessionStatusFailed == exportSession.status) { NSLog(@"AVAssetExportSessionStatusFailed"); } else { NSLog(@"Export Session Status: %d", exportSession.status); } }]; 

Answer 3

I made the same mistake as you dozens of times! The Apple API is really weird:

 CMTimeRange fadeInTimeRange = CMTimeRangeFromTimeToTime(startFadeInTime, endFadeInTime); CMTimeRange fadeOutTimeRange = CMTimeRangeFromTimeToTime(startFadeOutTime, endFadeOutTime); 

Must be:

 CMTimeRangeFromTimeToTime(startFadeInTime, fadeInDURATION); CMTimeRangeFromTimeToTime(startFadeOutTime, fadeOutDURATION); 

CMTimeRange is created from the beginning and duration, and not from the beginning to the end!

But in most cases, the end time is also a duration (if the start time is 0), then why so many people (including me) make a mistake.

And not a single Apple is intuitive!

Answer 4

This is my working code, just grab it and have a nice day!

 +(void)makeAudioFadeOutWithSourceURL:(NSURL*)sourceURL destinationURL:(NSURL*)destinationURL fadeOutBeginSecond:(NSInteger)beginTime fadeOutEndSecond:(NSInteger)endTime fadeOutBeginVolume:(CGFloat)beginVolume fadeOutEndVolume:(CGFloat)endVolume callback:(void(^)(BOOL))callback { NSAssert(callback, @"need callback"); NSParameterAssert(beginVolume >= 0 && beginVolume <=1); NSParameterAssert(endVolume >= 0 && endVolume <= 1); BOOL sourceExist = [[NSFileManager defaultManager] fileExistsAtPath:sourceURL.path]; NSAssert(sourceExist, @"source not exist"); AVURLAsset *asset = [AVAsset assetWithURL:sourceURL];; AVAssetExportSession* exporter = [AVAssetExportSession exportSessionWithAsset:asset presetName:AVAssetExportPresetAppleM4A]; exporter.outputURL = destinationURL; exporter.outputFileType = AVFileTypeAppleM4A; AVMutableAudioMix *exportAudioMix = [AVMutableAudioMix audioMix]; AVMutableAudioMixInputParameters *exportAudioMixInputParameters = [AVMutableAudioMixInputParameters audioMixInputParametersWithTrack:asset.tracks.lastObject]; [exportAudioMixInputParameters setVolumeRampFromStartVolume:beginVolume toEndVolume:endVolume timeRange:CMTimeRangeMake(CMTimeMakeWithSeconds(beginTime, 1), CMTimeSubtract(CMTimeMakeWithSeconds(endTime, 1), CMTimeMakeWithSeconds(beginTime, 1)))]; NSArray *audioMixParameters = @[exportAudioMixInputParameters]; exportAudioMix.inputParameters = audioMixParameters; exporter.audioMix = exportAudioMix; [exporter exportAsynchronouslyWithCompletionHandler:^(void){ AVAssetExportSessionStatus status = exporter.status; if (status != AVAssetExportSessionStatusCompleted) { if (callback) { callback(NO); } } else { if (callback) { callback(YES); } } NSError *error = exporter.error; NSLog(@"export done,error %@,status %d",error,status); }]; }