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• Volume Detect on half second window sizes [duplicate]

  14 juin 2021, par user82395214

  How can I get the max volume of individual slices of a video using FFMpeg ?

  


  Using this command, you can obtain the max volume for the whole clip :

  


  ffmpeg -i video.avi -af "volumedetect" -vn -sn -dn -f null /dev/null

  


  However, I want the max volume for every half second window in the audio file. How can I achieve this with ffmpeg ?

  


• How to detect black screen at play time in ijkplayer ?

  31 août 2019, par seaguest

  I am using ijkplayer,I am wondering if it is possible to know if current player is black screen at play time ?

  because some old model mobiles do not support hard-decode and get black screen, I need to know this case then switch to soft-decode.

• Swift - Workaround/Alternative to M3u8 to play mp4 segment or merge segments into mp4

  14 mai 2020, par STerrier

  I used AVAssetExportSession to download a session URL but the issue that you can't download live stream so to get around it, the live stream is split into 10 seconds mp4 segments that are downloaded using an m3u8 to create the URLs. I then use AVAssetExportSession to merge those mp4 segments.

  



  I can merge those clips one by one into one mp4 file which is what I want but as the file gets bigger, the longer it takes as I am dealing with thousands of segments which becomes unpractical.

  



  I thought about using AVplayerLooper but I cannot scrub, rewind or forward through the mp4 segment like a single video.

  



  Is there a way to combine the mp4 clips together to play as one video as the m3u8 does without merging ? or is there a fast way to merge videos ?

  



  Note : The server uses FFmpeg but I am not allowed to use FFmpeg or pods in the app.

  



  below is the function to merge videos

  



  var mp4Array: [AVAsset] = []
var avAssetExportSession: AVAssetExportSession?

var firstAsset: AVAsset?
var secondAsset: AVAsset?

func mergeVideos() {

    firstAsset = mp4Array.first
    secondAsset = mp4Array[1]

    guard let firstAsset = firstAsset, let secondAsset = secondAsset else { return }
    let mixComposition = AVMutableComposition()

    guard let firstTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)) else {return}

    do {

        try firstTrack.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: firstAsset.duration),
                                       of: firstAsset.tracks(withMediaType: .video)[0],
                                       at: CMTime.zero)

    } catch {
        print("Couldn't load track 1")
        return
    }

    guard let secondTrack = mixComposition.addMutableTrack(withMediaType: .video, preferredTrackID: Int32(kCMPersistentTrackID_Invalid)) else {return}

    do {
        try secondTrack.insertTimeRange(CMTimeRangeMake(start: CMTime.zero, duration: secondAsset.duration),
                                        of: secondAsset.tracks(withMediaType: .video)[0],
                                        at: firstAsset.duration)
    } catch {
        print("couldn't load track 2")
        return
    }

    let mainInstruction = AVMutableVideoCompositionInstruction()
    mainInstruction.timeRange = CMTimeRangeMake(start: CMTime.zero, duration: CMTimeAdd(firstAsset.duration, secondAsset.duration))

    let firstAssetInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: firstTrack)
    firstAssetInstruction.setOpacity(0.0, at: firstAsset.duration)

    let secondAssetInstruction = AVMutableVideoCompositionLayerInstruction(assetTrack: secondTrack)

    mainInstruction.layerInstructions = [firstAssetInstruction, secondAssetInstruction]
    let mainComposition = AVMutableVideoComposition()
    mainComposition.instructions = [mainInstruction]
    mainComposition.frameDuration = CMTimeMake(value: 1, timescale: 30)
    mainComposition.renderSize = firstTrack.naturalSize

    guard let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
    let url = documentDirectory.appendingPathComponent("MergedVideos/mergeVideo\(videoInt).mp4")

    guard let exporter = AVAssetExportSession(asset: mixComposition, presetName: AVAssetExportPresetHighestQuality) else {return}

    exporter.outputURL = url
    exporter.outputFileType = AVFileType.mp4
    exporter.shouldOptimizeForNetworkUse = true
    exporter.videoComposition = mainComposition

    exporter.exportAsynchronously {

        if exporter.status == .completed {
            let avasset = AVAsset(url:url)
            self.mergeUrl = avasset
            if self.mp4Array.count > 1{
                print("This add the merged video to the front of the mp4array")
                self.mp4Array.remove(at: 1)
                self.mp4Array.removeFirst()
                self.videoInt = self.videoInt + 1
                self.mp4Array.append(self.mergeUrl!)
                self.mp4Array.bringToFront(item: self.mp4Array.last!)
            }

            if (self.mp4Array.count > 1){
                if self.mergeUrl != nil {
                    self.mergeVideos()
                }
            } else {
                var numberofvideosdeleted = 0
                while (numberofvideosdeleted < self.videoInt - 1){
                    do {
                        print("deleting")
                        let url = documentDirectory.appendingPathComponent("MergedVideos/mergeVideo\(numberofvideosdeleted).mp4")
                        try FileManager.default.removeItem(at: url)
                        numberofvideosdeleted = numberofvideosdeleted + 1
                    } catch {
                        print("Error removing videos")
                    }
                }

                self.deleteCurrentSegementsInFolder()
            }
        }
    }
}