Exporting mp4 through AVAssetExportSession fails - swift

Question

I start saying that I spent a lot of time searching through documentation, posts here and somewhere else, but I can't figure out the solution for this problem.
I'm using AVAssetExportSession for exporting an .mp4 file stored in a AVAsset instance.
What I do is:
I check the isExportable property of AVAsset
I then get an array of exportPresets compatible with the AVAsset instance
I take the AVAssetExportPreset1920x1080, or, if not existing I try to export the media with AVAssetExportPresetPassthrough (FYI, 100% of times, the preset I need is always contained in the list, but I tried also the passthrough option and it doesn't work anyway)
The outputFileType is AVFileTypeMPEG4 and I tried also by assigning the .mp4 extension to the file, but nothing makes it work.
I always receive this error
Error Domain=AVFoundationErrorDomain Code=-11838 "Operation Stopped"
UserInfo={NSUnderlyingError=0x600000658c30 {Error
Domain=NSOSStatusErrorDomain Code=-12109 "(null)"},
NSLocalizedFailureReason=The operation is not supported for this
media., NSLocalizedDescription=Operation Stopped}
Below is the code I'm using
func _getDataFor(_ item: AVPlayerItem, completion: #escaping (Data?) -> ()) {
guard item.asset.isExportable else {
completion(nil)
return
}
let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: item.asset)
var preset: String = AVAssetExportPresetPassthrough
if compatiblePresets.contains(AVAssetExportPreset1920x1080) { preset = AVAssetExportPreset1920x1080 }
guard
let exportSession = AVAssetExportSession(asset: item.asset, presetName: preset),
exportSession.supportedFileTypes.contains(AVFileTypeMPEG4) else {
completion(nil)
return
}
var tempFileUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("temp_video_data.mp4", isDirectory: false)
tempFileUrl = URL(fileURLWithPath: tempFileUrl.path)
exportSession.outputURL = tempFileUrl
exportSession.outputFileType = AVFileTypeMPEG4
let startTime = CMTimeMake(0, 1)
let timeRange = CMTimeRangeMake(startTime, item.duration)
exportSession.timeRange = timeRange
exportSession.exportAsynchronously {
print("\(exportSession.error)")
let data = try? Data(contentsOf: tempFileUrl)
_ = try? FileManager.default.removeItem(at: tempFileUrl)
completion(data)
}
}

Answer 1

Seems like converting the AVAsset instance in a AVMutableComposition did the trick. If, please, anyone knows the reason why this works let me know.
This is the new _getDataFor(_:completion:) method implementation
func _getDataFor(_ item: AVPlayerItem, completion: #escaping (Data?) -> ()) {
guard item.asset.isExportable else {
completion(nil)
return
}
let composition = AVMutableComposition()
let compositionVideoTrack = composition.addMutableTrack(withMediaType: AVMediaTypeVideo, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
let compositionAudioTrack = composition.addMutableTrack(withMediaType: AVMediaTypeAudio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
let sourceVideoTrack = item.asset.tracks(withMediaType: AVMediaTypeVideo).first!
let sourceAudioTrack = item.asset.tracks(withMediaType: AVMediaTypeAudio).first!
do {
try compositionVideoTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, item.duration), of: sourceVideoTrack, at: kCMTimeZero)
try compositionAudioTrack.insertTimeRange(CMTimeRangeMake(kCMTimeZero, item.duration), of: sourceAudioTrack, at: kCMTimeZero)
} catch(_) {
completion(nil)
return
}
let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: composition)
var preset: String = AVAssetExportPresetPassthrough
if compatiblePresets.contains(AVAssetExportPreset1920x1080) { preset = AVAssetExportPreset1920x1080 }
guard
let exportSession = AVAssetExportSession(asset: composition, presetName: preset),
exportSession.supportedFileTypes.contains(AVFileTypeMPEG4) else {
completion(nil)
return
}
var tempFileUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0].appendingPathComponent("temp_video_data.mp4", isDirectory: false)
tempFileUrl = URL(fileURLWithPath: tempFileUrl.path)
exportSession.outputURL = tempFileUrl
exportSession.outputFileType = AVFileTypeMPEG4
let startTime = CMTimeMake(0, 1)
let timeRange = CMTimeRangeMake(startTime, item.duration)
exportSession.timeRange = timeRange
exportSession.exportAsynchronously {
print("\(tempFileUrl)")
print("\(exportSession.error)")
let data = try? Data(contentsOf: tempFileUrl)
_ = try? FileManager.default.removeItem(at: tempFileUrl)
completion(data)
}
}

Answer 2

Swift 5:
import Foundation
import AVKit
func getDataFor(_ asset: AVAsset, completion: #escaping (Data?) -> ()) {
guard asset.isExportable,
let sourceVideoTrack = asset.tracks(withMediaType: .video).first,
let sourceAudioTrack = asset.tracks(withMediaType: .audio).first else {
completion(nil)
return
}
let composition = AVMutableComposition()
let compositionVideoTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
let compositionAudioTrack = composition.addMutableTrack(withMediaType: .audio, preferredTrackID: CMPersistentTrackID(kCMPersistentTrackID_Invalid))
do {
try compositionVideoTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: asset.duration), of: sourceVideoTrack, at: .zero)
try compositionAudioTrack?.insertTimeRange(CMTimeRangeMake(start: .zero, duration: asset.duration), of: sourceAudioTrack, at: .zero)
} catch {
completion(nil)
return
}
let compatiblePresets = AVAssetExportSession.exportPresets(compatibleWith: composition)
var preset = AVAssetExportPresetPassthrough
let preferredPreset = AVAssetExportPreset1920x1080
if compatiblePresets.contains(preferredPreset) {
preset = preferredPreset
}
let fileType: AVFileType = .mp4
guard let exportSession = AVAssetExportSession(asset: composition, presetName: preset),
exportSession.supportedFileTypes.contains(fileType) else {
completion(nil)
return
}
let tempFileUrl = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("temp_video_data")
exportSession.outputURL = tempFileUrl
exportSession.outputFileType = fileType
let startTime = CMTimeMake(value: 0, timescale: 1)
let timeRange = CMTimeRangeMake(start: startTime, duration: asset.duration)
exportSession.timeRange = timeRange
exportSession.exportAsynchronously {
print(tempFileUrl)
print(String(describing: exportSession.error))
let data = try? Data(contentsOf: tempFileUrl)
try? FileManager.default.removeItem(at: tempFileUrl)
completion(data)
}
}

Answer 3

Check if you set delegate property for AVURLAsset correctly.
[self.playerAsset.resourceLoader setDelegate:self queue:dispatch_get_main_queue()];
And conform to AVAssetResourceLoaderDelegate protocol.
That is all you need to do.

Answer 4

I had this same issue because I was adding an audio track to a video without audio. Removing the audio track fixed it.

Answer 5

I ran into this problem because the Microphone permission was off/denied. Once I set turned it on this error went away.

Answer 6

I solved this problem by removing the CompositionTrack with media type .audio and empty segments from the AVMutableComposition
if let audioTrack = exportComposition.tracks(withMediaType: .audio).first,
audioTrack.segments.isEmpty {
exportComposition.removeTrack(audioTrack)
}

Answer 7

I had the same error, when I try to ExportSession with AVAssetExportPresetPassthrough always fail and in my case I can't use another preset because I must have the same resolution like at origin video
I fixed
let asset = AVAsset(url: originUrl)
let videoTrack = asset.tracks( withMediaType: .video ).first! as AVAssetTrack
let videoComposition = AVMutableVideoComposition()
videoComposition.renderSize = CGSize(
width: videoTrack.naturalSize.width,
height: videoTrack.naturalSize.height
)
videoComposition.frameDuration = CMTime(
value: 1,
timescale: videoTrack.naturalTimeScale
)
let transformer = AVMutableVideoCompositionLayerInstruction(
assetTrack: videoTrack
)
transformer.setOpacity(1.0, at: CMTime.zero)
let instruction = AVMutableVideoCompositionInstruction()
instruction.timeRange = timeRange
instruction.layerInstructions = [transformer]
videoComposition.instructions = [instruction]
guard let exportSession = AVAssetExportSession(
asset: asset,
presetName: AVAssetExportPresetMediumQuality
) else {
return handleFailure(error: .mediaSavingError, completion: completion)
}
exportSession.videoComposition = videoComposition
exportSession.outputURL = outputUrl
exportSession.outputFileType = .mp4
exportSession.timeRange = timeRange
exportSession.exportAsynchronously { [weak self] in
"your code"
}
Forks great for me, and it's saved the same resolution as video before