Recherche avancée

Sur d’autres sites (5663)

• Ffmpeg libx264rgb and libx264 yuv444p gives very different results

  1er février 2020, par Mustafa Akın Yılmaz

  I am trying to create a lossy compressed video from several .png files. I am using the following ffmpeg commdans :

  



  ffmpeg -i %8d.png -frames:v 4 -c:v libx264rgb -pix_fmt rgb24 -g 4 -qp 30 -r 25 out.mp4


  



  and

  



  ffmpeg -i %8d.png -frames:v 4 -c:v libx264 -pix_fmt yuv444p -g 4 -qp 30 -r 25 out.mp4


  



  Then I am extracting frames from the videos with the command :

  



  ffmpeg -i out.mp4 -r 25 %8d.png


  



  When I compare the bitrate and PSNR, I found that the yuv444p gives about 2 db gain at the same bitrate. Why such a huge difference is observed even I did set yuv444p which does not apply chroma subsampling ?

  


• Find videos with specific codec in a directory and move them to another directory [closed]

  31 janvier 2020, par sergeantSalty

  iam trying to find all videos in a directory that have the h264 codec and then move them to another directory.
  The problem iam facing is not to move them but to find the videos.

  Here is what I have so far.

  > @echo off
  
  set "ffprobe=C:\ffmpeg\bin\ffprobe.exe -v error -select_streams v:0 -show_entries stream=codec_name -of default=noprint_wrappers=1:nokey=1"
  
  FOR /R %%f IN (*.mkv) DO (
  
  
  
  %ffprobe% "%%f" 
  
  )   
  
  PAUSE()

  When I run this, I see the codecs in cmd correctly. But when I try to compare the codec and then move them it wont do anything.

  Some pseudocode

  if outputOfFFprobe == "h264" then move

  How can I compare the output from ffprobe.exe to the string "h264" and if it matches then move the file to another directory.

  Iam grateful for any suggestions !

• How do I encode iOS videos as .mp4 from UIImagePickerController so that Android devices can play them ?

  22 septembre 2022, par Iain Coleman

  I am using UIImagePickerController to record short (<30s) videos which are then saved and uploaded via our API. The app is cross-platform and so I need recorded videos to be encoded into mp4 format so that Android devices can play them.

  &#xA;&#xA;

  I used instructions from the following questions to create my solution :

  &#xA;&#xA;

  Swift - How to record video in MP4 format with UIImagePickerController ?

  &#xA;&#xA;

  AVFoundation record video in MP4 format

  &#xA;&#xA;

  https://forums.developer.apple.com/thread/94762

  &#xA;&#xA;

  I record my video through the UIImagePickerController like so :

  &#xA;&#xA;

      func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    // Local variable inserted by Swift 4.2 migrator.
    let info = convertFromUIImagePickerControllerInfoKeyDictionary(info)


    let videoNSURL = info[convertFromUIImagePickerControllerInfoKey(UIImagePickerController.InfoKey.mediaURL)] as? NSURL

    videoURL = videoNSURL!.absoluteURL
    if let videoURL = videoURL {
        let avAsset = AVURLAsset(url: videoURL, options: nil)

        avAsset.exportVideo { (exportedURL) in
            if let uploadVC = self.uploadVC {
                uploadVC.incomingFileURL = exportedURL
                uploadVC.myJewelleryID = self.myJewelleryID
                uploadVC.topicID = self.topicID
            }
            DispatchQueue.main.async { [weak self] in
              //Update UI with results from previous closure
                self?.dismiss(animated: true, completion: nil)
                self?.showUploadContainer()
                self?.updateVideoContainerWithURL(url: exportedURL)
            }
        }
    }
}


  &#xA;&#xA;

  This then passes the exported MP4 url to the upload container view, where it saves the file to the device :

  &#xA;&#xA;

  private func saveVideoFileToDevice() {

    //Filename Struct = [AssetID]_[TopicID]_[CustomerID]_[Datestamp]
    let date = Date()
    let formater = DateFormatter()
    formater.locale = Locale(identifier: "en_US_POSIX")
    formater.dateFormat = "YYYY-MM-dd-HH-mm-ss"

    uploadFileName = ""
    if let mjID = myJewelleryID {
        uploadFileName = "ASID_\(mjID)_\(User.instance.customerID)_\(formater.string(from: date)).mp4"
    } else if let tID = topicID {
        uploadFileName = "ASID_\(tID)_\(User.instance.customerID)_\(formater.string(from: date)).mp4"
    }

    let fileManager = FileManager.default

    if let destURL = URL(string: "file://\(NSHomeDirectory())/Documents/\(uploadFileName!)") {

        var fileData: Data!
        print("destURL = \(destURL)")
        do {
            try fileManager.copyItem(at: incomingFileURL! as URL, to: destURL)
            fileData = try Data(contentsOf: incomingFileURL! as URL)

            try fileData.write(to: destURL)


        }
        catch {
            print("DEBUG: Failed to save video data")
        }
    }
}


  &#xA;&#xA;

  and then uploads the file to our API. Although the file is MP4, it does not play on Android. On inspection, the file looks very similar to a file that will actually play on an Android device when we compare the codec data :

  &#xA;&#xA;

  

  &#xA;&#xA;

  Does anyone have any ideas on how I can fix this ?

  &#xA;&#xA;

  Thanks !

  &#xA;