问题
I am working on Video based Application in Swift. As per the requirement I have to select multiple Videos from Device Gallery, setting up different different CIFilter effects and Volume for each Video Asset and then merge all the Videos and have to Save the Final Video. As an output, when I will play the Final Video then Video sound volume should change accordingly.
I have already merged all the selected Video Assets into one with different different CIFilter effects but my problem is when I am trying to set Volume for each Video Clips then it's not working. I am getting the default Volume for my Final Video. Here is my code:
func addFilerEffectAndVolumeToIndividualVideoClip(_ assetURL: URL, video: VideoFileModel, completion : ((_ session: AVAssetExportSession?, _ outputURL : URL?) -> ())?){
let videoFilteredAsset = AVAsset(url: assetURL)
print(videoFilteredAsset)
createVideoComposition(myAsset: videoFilteredAsset, videos: video)
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let url = URL(fileURLWithPath: documentDirectory).appendingPathComponent("\(video.fileID)_\("FilterVideo").mov")
let filePath = url.path
let fileManager = FileManager.default
do {
if fileManager.fileExists(atPath: filePath) {
print("FILE AVAILABLE")
try fileManager.removeItem(atPath:filePath)
} else {
print("FILE NOT AVAILABLE")
}
} catch _ {
}
let composition: AVMutableComposition = AVMutableComposition()
let compositionVideo: AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let compositionAudioVideo: AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
//Add video to the final record
do {
try compositionVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoFilteredAsset.duration), of: videoFilteredAsset.tracks(withMediaType: AVMediaTypeVideo)[0], at: kCMTimeZero)
} catch _ {
}
//Extract audio from the video and the music
let audioMix: AVMutableAudioMix = AVMutableAudioMix()
var audioMixParam: [AVMutableAudioMixInputParameters] = []
let assetVideoTrack: AVAssetTrack = videoFilteredAsset.tracks(withMediaType: AVMediaTypeAudio)[0]
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = compositionAudioVideo.trackID
//Set final volume of the audio record and the music
videoParam.setVolume(video.videoClipVolume, at: kCMTimeZero)
//Add setting
audioMixParam.append(videoParam)
//Add audio on final record
do {
try compositionAudioVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, videoFilteredAsset.duration), of: assetVideoTrack, at: kCMTimeZero)
} catch _ {
assertionFailure()
}
//Fading volume out for background music
let durationInSeconds = CMTimeGetSeconds(videoFilteredAsset.duration)
let firstSecond = CMTimeRangeMake(CMTimeMakeWithSeconds(0, 1), CMTimeMakeWithSeconds(1, 1))
let lastSecond = CMTimeRangeMake(CMTimeMakeWithSeconds(durationInSeconds-1, 1), CMTimeMakeWithSeconds(1, 1))
videoParam.setVolumeRamp(fromStartVolume: 0, toEndVolume: video.videoClipVolume, timeRange: firstSecond)
videoParam.setVolumeRamp(fromStartVolume: video.videoClipVolume, toEndVolume: 0, timeRange: lastSecond)
//Add parameter
audioMix.inputParameters = audioMixParam
// Export part, left for facility
let exporter = AVAssetExportSession(asset: videoFilteredAsset, presetName: AVAssetExportPresetHighestQuality)!
exporter.videoComposition = videoFilterComposition
exporter.outputURL = url
exporter.outputFileType = AVFileTypeQuickTimeMovie
exporter.audioMix = audioMix
exporter.exportAsynchronously(completionHandler: { () -> Void in
completion!(exporter, url)
})
}
After that again I am using a method to merge all the Video Clips using AVAssetExportSession, there I am not setting any AudioMixInputParameters.
Note: When I am setting up volume in final merging method using AVAssetExportSession's AudioMixInputParameters, then Volume is getting change for full Video.
My question: Is it possible to set multiple volume for each Video Clips. Please suggest. Thank you!
回答1:
Here is the working solution for my question:
func addVolumeToIndividualVideoClip(_ assetURL: URL, video: VideoFileModel, completion : ((_ session: AVAssetExportSession?, _ outputURL : URL?) -> ())?){
//Create Asset from Url
let filteredVideoAsset: AVAsset = AVAsset(url: assetURL)
video.fileID = String(video.videoID)
//Get the path of App Document Directory
let documentDirectory = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
let url = URL(fileURLWithPath: documentDirectory).appendingPathComponent("\(video.fileID)_\("FilterVideo").mov")
let filePath = url.path
let fileManager = FileManager.default
do {
if fileManager.fileExists(atPath: filePath) {
print("FILE AVAILABLE")
try fileManager.removeItem(atPath:filePath)
} else {
print("FILE NOT AVAILABLE")
}
} catch _ {
}
let composition: AVMutableComposition = AVMutableComposition()
let compositionVideo: AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID())
let compositionAudioVideo: AVMutableCompositionTrack = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID())
//Add video to the final record
do {
try compositionVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, filteredVideoAsset.duration), of: filteredVideoAsset.tracks(withMediaType: AVMediaTypeVideo)[0], at: kCMTimeZero)
} catch _ {
}
//Extract audio from the video and the music
let audioMix: AVMutableAudioMix = AVMutableAudioMix()
var audioMixParam: [AVMutableAudioMixInputParameters] = []
let assetVideoTrack: AVAssetTrack = filteredVideoAsset.tracks(withMediaType: AVMediaTypeAudio)[0]
let videoParam: AVMutableAudioMixInputParameters = AVMutableAudioMixInputParameters(track: assetVideoTrack)
videoParam.trackID = compositionAudioVideo.trackID
//Set final volume of the audio record and the music
videoParam.setVolume(video.videoVolume, at: kCMTimeZero)
//Add setting
audioMixParam.append(videoParam)
//Add audio on final record
//First: the audio of the record and Second: the music
do {
try compositionAudioVideo.insertTimeRange(CMTimeRangeMake(kCMTimeZero, filteredVideoAsset.duration), of: assetVideoTrack, at: kCMTimeZero)
} catch _ {
assertionFailure()
}
//Fading volume out for background music
let durationInSeconds = CMTimeGetSeconds(filteredVideoAsset.duration)
let firstSecond = CMTimeRangeMake(CMTimeMakeWithSeconds(0, 1), CMTimeMakeWithSeconds(1, 1))
let lastSecond = CMTimeRangeMake(CMTimeMakeWithSeconds(durationInSeconds-1, 1), CMTimeMakeWithSeconds(1, 1))
videoParam.setVolumeRamp(fromStartVolume: 0, toEndVolume: video.videoVolume, timeRange: firstSecond)
videoParam.setVolumeRamp(fromStartVolume: video.videoVolume, toEndVolume: 0, timeRange: lastSecond)
//Add parameter
audioMix.inputParameters = audioMixParam
//Remove the previous temp video if exist
let filemgr = FileManager.default
do {
if filemgr.fileExists(atPath: "\(video.fileID)_\("FilterVideo").mov") {
try filemgr.removeItem(atPath: "\(video.fileID)_\("FilterVideo").mov")
} else {
}
} catch _ {
}
//Exporte the final record’
let exporter: AVAssetExportSession = AVAssetExportSession(asset: composition, presetName: AVAssetExportPresetHighestQuality)!
exporter.outputURL = url
exporter.outputFileType = AVFileTypeMPEG4
exporter.audioMix = audioMix
exporter.exportAsynchronously(completionHandler: { () -> Void in
completion!(exporter, url)
// self.saveVideoToLibrary(from: filePath)
})
}
回答2:
I found, that exporting an asset with preset of AVAssetExportPresetPassthrough doesn't have an impact on output volume. When I tried to use AVAssetExportPresetLowQuality, volume change successfully applied.
I wish it is better documented somewhere :(
The working code:
// Assume we have:
let composition: AVMutableComposition
var inputParameters = [AVAudioMixInputParameters]()
// We add a track
let trackComposition = composition.addMutableTrack(...)
// Configure volume for this track
let inputParameter = AVMutableAudioMixInputParameters(track: trackComposition)
inputParameter.setVolume(desiredVolume, at: startTime)
// It works even without setting the `trackID`
// inputParameter.trackID = trackComposition.trackID
inputParameters.append(inputParameter)
// Apply gathered `inputParameters` before exporting
let audioMix = AVMutableAudioMix()
audioMix.inputParameters = inputParameters
// I found it's not working, if using `AVAssetExportPresetPassthrough`,
// so try `AVAssetExportPresetLowQuality` first
let export = AVAssetExportSession(..., presetName: AVAssetExportPresetLowQuality)
export.audioMix = audioMix
Tested this with multiple assetTrack insertions to the same compositionTrack, setting different volume for each insertion. Seems to be working.
来源：https://stackoverflow.com/questions/54804888/setting-multiple-volumes-to-each-video-tracks-using-audiomixinputparameters-avfo