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• Using Flutter FFMPEG_KIT to convert a sequence of RGBA images into a mp4 video

  30 avril 2023, par jdevp2

  I’m trying to convert a sequence of RGBA byte images into an MP4 video by using Flutter FFMPEGKit package. The following is the code snippet but it gives me an error. I’m not sure what is the correct option that I should use to convert a set of rawrgba images to a video. I appreciate any help.

  


   static Future<void> videoEncoder() async {&#xA;    appTempDir = &#x27;${(await getTemporaryDirectory()).path}/workPath&#x27;;&#xA;   &#xA;    FFmpegKit.execute(&#xA;           &#x27;-hide_banner -y -f rawvideo -pix_fmt rgba -i appTempDir/input%d.rgba -c:v mpeg4  -r 12 appTempDir/output.mp4&#x27;)&#xA;     .then((session) async {&#xA;       final returnCode = await session.getReturnCode();&#xA;      if (ReturnCode.isSuccess(returnCode)) {&#xA;        print(&#x27;SUCCESS&#x27;);&#xA;      } else if (ReturnCode.isCancel(returnCode)) {&#xA;        print(&#x27;CANCEL&#x27;);&#xA;      } else {&#xA;        print(&#x27;ERROR&#x27;);&#xA;      }&#xA;    });&#xA;  }&#xA;}&#xA;</void>

  


  The image rgba data is saved via the following code snippet.

  


  Utils.getBuffer(renderKey).then((value) async {
        ui.Image buffer = value;
        final data =
            await buffer!.toByteData(format: ui.ImageByteFormat.rawRgba);
        Uint8List uData = data!.buffer.asUint8List();
        VideoUtil.saveImageFileToDirectory(uData, 'input$frameNum.rgba');
        frameNum++;
        });


  


• Using HEVC with Alpha to Compose Moviepy Video

  3 avril, par James Grace

  I'm using moviepy, PIL and numpy and trying to compile a video with 3 components : A background image that is a PNG with no transparency, an Overlay Video that is a HEVC with Alpha, and a primary clip that is produced with a collection of PNG images with transparency.

  


  The video is composed with background + overlay video + main video.

  


  The problem I'm having is that the overlay video has a black background, so the background image is covered completely. Moviepy is able to import the HEVC video successfully by it seems as though the Alpha channel is lost on import.

  


  Any ideas ?

  


  Here's my code :

  


  from PIL import Image
import moviepy.editor as mpe
import numpy as np

def CompileVideo() :

    frames = ["list_of_png_files_with_transparency"]
    fps = 30.0
    clips = [mpe.ImageClip(np.asarray(Image.open(frame))).set_duration(1 / int(fps)) for frame in frames]
    ad_clip = mpe.concatenate_videoclips(clips, method="compose")
    bg_clip = mpe.ImageClip(np.asarray(Image.open("path_to_background_file_no_transparency"))).set_duration(ad_clip.duration)

    overlay_clip = mpe.VideoFileClip("path_to_HEVC_with_Alpha.mov")

    comp = [bg_clip, overlay_clip, ad_clip]

    final = mpe.CompositeVideoClip(comp).set_duration(ad_clip.duration)
    final.write_videofile("output.mp4", fps=fps)


  


• JavaCV FFmpegFrameGrabber preload audio

  1er juillet 2015, par James

  I have an application that streams video data to a RTMP server using javacv’s FFmpegFrameRecorder. I want to add some audio to this stream from a separate file - a short sound clip that I want to play on repeat.

  Given the sound clip is very short, I want to preload the audio data into memory and just loop over it - so I can avoid excessive IO etc.

  I’ve attempted to add audio to the stream using javacv’s FFmpegFrameGrabber, as prescribed on multiple tutorials.

  The addition of audio works perfectly if I don’t attempt to preload/cache any of the audio data, for example :

  private FFmpegFrameRecorder frameRecorder;
  
  private FFmpegFrameGrabber frameGrabber;
  
  
  
  ...
  
  //frameRecorder and frameGrabber setup during initialization
  
  ...
  
  
  
  public void record(IplImage image) {
  
          try {
  
              frameRecorder.record(image);
  
              Frame frame = frameGrabber.grabFrame();
  
              if(frame == null) {
  
                  frameGrabber = new FFmpegFrameGrabber("audioFileHere.wav");
  
                  frameGrabber.start();
  
                  frame = frameGrabber.grabFrame();
  
              }
  
              frameRecorder.record(frame);
  
          } catch (FrameRecorder.Exception e) {
  
              log.error(getMarker(FATAL), "Can't record frame!", e);
  
          } catch (FrameGrabber.Exception e) {
  
              log.error(getMarker(FATAL), "Can't record frame!", e);
  
          }
  
  }

  However, if I try to preload the audio data I get garbage sound being played :

  private FFmpegFrameRecorder frameRecorder;
  
  private List<framedata> audioData;
  
  
  
  private static final class FrameData {
  
      public final Buffer[] samples;
  
      public final Integer sampleRate;
  
      public final Integer audioChannels;
  
  
  
      //Constructors, getters and setters here
  
  }
  
  
  
  ...
  
      //frameRecorder setup during initialization
  
      audioData = new ArrayList&lt;>();
  
      FFmpegFrameGrabber audioGrabber = new FFmpegFrameGrabber("audioFileHere.wav");
  
      try {
  
          audioGrabber.start();
  
          Frame frame;
  
          while ((frame = audioGrabber.grabFrame()) != null) {
  
              Buffer[] buffers = frame.samples;
  
              Buffer[] copiedBuffers = new Buffer[buffers.length];
  
              for (int i = 0; i &lt; buffers.length; i++) {
  
                  copiedBuffers[i] = ((ShortBuffer) buffers[i]).duplicate();
  
              }
  
              FrameData frameData = new FrameData(copiedBuffers, frame.sampleRate, frame.audioChannels);
  
              audioData.add(frameData);
  
          }
  
      } catch (FrameGrabber.Exception e) {
  
          e.printStackTrace();
  
      }
  
  ...
  
  
  
  private int frameCount = 0;
  
  
  
  public void record(IplImage image) {
  
      frameCount++;
  
      try {
  
          FrameData frameData = audioData.get(frameCount % audioData.size());
  
          frameRecorder.record(image);
  
          frameRecorder.record(frameData.sampleRate, frameData.audioChannels, frameData.samples);
  
      } catch (FrameRecorder.Exception e) {
  
          log.error(getMarker(FATAL), "Can't record frame!", e);
  
      }
  
  }
  
  </framedata>

  NOTE : I have to deep copy the Frame object because FFmpegFrameGrabber.grabFrame() recycles a single Frame object

  Can someone explain why this doesn’t work and/or how I could achieve the desired result ?