AVMutableAudioMixInputParameters: setVolume() doesn't work with audio file iOS 9 - ios

Question

I try to mix a video record with an audio file from the iPod library of the device.
I want to set the volume of each audio (the audio of the video and the audio file).
I try to use AVMutableAudioMixInputParameters object with the method setVolume().
I don't have any problem with the volume of the video, but the volume of the audio file on the final record is always set at max. I tried to change the audio file for testing using a video and take only the audio track of this video, and that works fine.
import UIKit
import AVFoundation
class AVTools: NSObject {
/**
volume: between 1.0 and 0.0
*/
class func mergeVideoAndMusicWithVolume(videoURL: NSURL, audioURL: NSURL, startAudioTime: Float64, volumeVideo: Float, volumeAudio: Float, complete: (NSURL?) -> Void) -> Void {
//The goal is merging a video and a music from iPod library, and set it a volume
//Get the path of App Document Directory
let dirPaths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
let docsDir = dirPaths[0] as String
//Create Asset from record and music
let assetVideo: AVURLAsset = AVURLAsset(URL: videoURL)
let assetMusic: AVURLAsset = AVURLAsset(URL: audioURL)
let composition: AVMutableComposition = AVMutableComposition()
let compositionVideo: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let compositionAudioVideo: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
let compositionAudioMusic: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
//Add video to the final record
do {
try compositionVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, assetVideo.duration), ofTrack: assetVideo.tracksWithMediaType(AVMediaTypeVideo)[0], atTime: kCMTimeZero)
} catch _ {
}
//Extract audio from the video and the music
let audioMix: AVMutableAudioMix = AVMutableAudioMix()
var audioMixParam: [AVMutableAudioMixInputParameters] = []
let assetVideoTrack: AVAssetTrack = assetVideo.tracksWithMediaType(AVMediaTypeAudio)[0]
let assetMusicTrack: AVAssetTrack = assetMusic.tracksWithMediaType(AVMediaTypeAudio)[0]
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = assetVideoTrack.trackID
let musicParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetMusicTrack)
musicParam.trackID = assetMusicTrack.trackID
//Set final volume of the audio record and the music
videoParam.setVolume(volumeVideo, atTime: kCMTimeZero)
musicParam.setVolume(volumeAudio, atTime: kCMTimeZero) // <----- This doesn't work on audio file
//Add setting
audioMixParam.append(musicParam)
audioMixParam.append(videoParam)
//Add audio on final record
//First: the audio of the record and Second: the music
do {
try compositionAudioVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, assetVideo.duration), ofTrack: assetVideoTrack, atTime: kCMTimeZero)
} catch _ {
assertionFailure()
}
do {
try compositionAudioMusic.insertTimeRange(CMTimeRangeMake(CMTimeMake(Int64(startAudioTime * 10000), 10000), assetVideo.duration), ofTrack: assetMusicTrack, atTime: kCMTimeZero)
} catch _ {
assertionFailure()
}
//Add parameter
audioMix.inputParameters = audioMixParam
//Remove the previous temp video if exist
let filemgr = NSFileManager.defaultManager()
do {
if filemgr.fileExistsAtPath("\(docsDir)/movie-merge-music.mov") {
try filemgr.removeItemAtPath("\(docsDir)/movie-merge-music.mov")
} else {
}
} catch _ {
}
//Exporte the final record’
let completeMovie = "\(docsDir)/movie-merge-music.mov"
let completeMovieUrl = NSURL(fileURLWithPath: completeMovie)
let exporter: AVAssetExportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality)!
exporter.outputURL = completeMovieUrl
exporter.outputFileType = AVFileTypeMPEG4
exporter.audioMix = audioMix
exporter.exportAsynchronouslyWithCompletionHandler({
switch exporter.status{
case AVAssetExportSessionStatus.Failed:
print("failed \(exporter.error)")
complete(nil)
case AVAssetExportSessionStatus.Cancelled:
print("cancelled \(exporter.error)")
complete(nil)
default:
print("complete")
complete(completeMovieUrl)
}
})
}
}

Answer 1

Ok I've find the problem.
The problem is I assign the trackID of the asset and not the trackID of the composition.
For fix it, just replace:
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = assetVideoTrack.trackID
let musicParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetMusicTrack)
musicParam.trackID = assetMusicTrack.trackID
to:
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = compositionAudioVideo.trackID
let musicParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetMusicTrack)
musicParam.trackID = compositionAudioMusic.trackID
the final result:
/**
volume: between 1.0 and 0.0
*/
class func mergeVideoAndMusicWithVolume(videoURL: NSURL, audioURL: NSURL, startAudioTime: Float64, volumeVideo: Float, volumeAudio: Float, complete: (NSURL?) -> Void) -> Void {
//The goal is merging a video and a music from iPod library, and set it a volume
//Get the path of App Document Directory
let dirPaths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
let docsDir = dirPaths[0] as String
//Create Asset from record and music
let assetVideo: AVURLAsset = AVURLAsset(URL: videoURL)
let assetMusic: AVURLAsset = AVURLAsset(URL: audioURL)
let composition: AVMutableComposition = AVMutableComposition()
let compositionVideo: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let compositionAudioVideo: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
let compositionAudioMusic: AVMutableCompositionTrack = composition.addMutableTrackWithMediaType(AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
//Add video to the final record
do {
try compositionVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, assetVideo.duration), ofTrack: assetVideo.tracksWithMediaType(AVMediaTypeVideo)[0], atTime: kCMTimeZero)
} catch _ {
}
//Extract audio from the video and the music
let audioMix: AVMutableAudioMix = AVMutableAudioMix()
var audioMixParam: [AVMutableAudioMixInputParameters] = []
let assetVideoTrack: AVAssetTrack = assetVideo.tracksWithMediaType(AVMediaTypeAudio)[0]
let assetMusicTrack: AVAssetTrack = assetMusic.tracksWithMediaType(AVMediaTypeAudio)[0]
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = compositionAudioVideo.trackID
let musicParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetMusicTrack)
musicParam.trackID = compositionAudioMusic.trackID
//Set final volume of the audio record and the music
videoParam.setVolume(volumeVideo, atTime: kCMTimeZero)
musicParam.setVolume(volumeAudio, atTime: kCMTimeZero)
//Add setting
audioMixParam.append(musicParam)
audioMixParam.append(videoParam)
//Add audio on final record
//First: the audio of the record and Second: the music
do {
try compositionAudioVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, assetVideo.duration), ofTrack: assetVideoTrack, atTime: kCMTimeZero)
} catch _ {
assertionFailure()
}
do {
try compositionAudioMusic.insertTimeRange(CMTimeRangeMake(CMTimeMake(Int64(startAudioTime * 10000), 10000), assetVideo.duration), ofTrack: assetMusicTrack, atTime: kCMTimeZero)
} catch _ {
assertionFailure()
}
//Add parameter
audioMix.inputParameters = audioMixParam
//Remove the previous temp video if exist
let filemgr = NSFileManager.defaultManager()
do {
if filemgr.fileExistsAtPath("\(docsDir)/movie-merge-music.mov") {
try filemgr.removeItemAtPath("\(docsDir)/movie-merge-music.mov")
} else {
}
} catch _ {
}
//Exporte the final record’
let completeMovie = "\(docsDir)/movie-merge-music.mov"
let completeMovieUrl = NSURL(fileURLWithPath: completeMovie)
let exporter: AVAssetExportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality)!
exporter.outputURL = completeMovieUrl
exporter.outputFileType = AVFileTypeMPEG4
exporter.audioMix = audioMix
exporter.exportAsynchronouslyWithCompletionHandler({
switch exporter.status{
case AVAssetExportSessionStatus.Failed:
print("failed \(exporter.error)")
complete(nil)
case AVAssetExportSessionStatus.Cancelled:
print("cancelled \(exporter.error)")
complete(nil)
default:
print("complete")
complete(completeMovieUrl)
}
})
}