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• How to get iOS App Preview video bitrate in range

  29 avril 2019, par JKaz

  Creating new App Previews for App Store Connect has always been difficult. Time to do it again (new app version) and running into same issue without resolution this time.

  Making the video is easy enough, recording it with Quicktime and either a connected device or through Simulator (and the xcrun simctl io booted recordVideo <filename>.<file extension="extension"></file></filename> Terminal command).

  I can open that in iMovie, create a new App Preview, and export/share the preview with proper size, length, frame rate per Apple specs. But the bit rate is always too low ( 4 mbps) and it’s required to be 10-12 mbps (and I’ve had video reject be/c of that). In the past I could always make some change to the .mp4, in conjunction with something like ffmpeg -i ~/appVideo.mp4 -b:v 11M ~/appPreview.mp4 to get the file into the target range, but that’s not helping today, and neither is Developer Tech Support.

  Apple’s documentation says :

  To export the final video, click Share in the toolbar, then choose App
  Preview. The export settings are automatically configured to meet App
  Store requirements. iMovie exports the final video at the correct
  resolution based on the device from which your clips were captured.

  I’ve done that and more, and bit rate is still out of range (every other attribute is in spec). I’ve tried the recommendations from a bunch of other threads here for http://video.online-convert.com/convert-to-mp4 and others, and none seem to do the trick. Am I missing something obvious re bitrate ? Is it this hard for everyone ?

  Thank you.

• How to use ffmpeg to create a video slideshow from a set of images ? [on hold]

  15 mars 2015, par Ali Irani

  I want to create a 15 second video from 5 images with a fade effect between them and add counter on center of video that changes every second. The final video also needs an audio track.

  Can I do this with ffmpeg ?

• JavaFXFrameConverter consuming insane amounts of memory

  17 juillet 2023, par iexav

  The JavaFXFrameConverter (from the wrapper of the ffmpeg C library in java) convert() method is consuming an outrageous amount of memory. To elaborate a bit more, it does not happen usually. If I just make an instance of the class in my main method, grab a frame via FFMpegFrameGrabber and give it to the convert() method the memory usage is pretty much none. However, when I attempt to do pretty much the exact same in a class I made using an ExecutorService my memory usage jumps up to 8 gigabytes when convert is called. The converter and executor service are declared as member variables of my class. Namely :

  


      final JavaFXFrameConverter converter = new JavaFXFrameConverter();
    private  ExecutorService           videoExecutor;


  


  (the videoExecutor is instantiated in the constructor of the class :

  


  videoExecutor=Executors.newSingleThreadExecutor();


  


  Now, the method I am using for processing of the video frames is this :

  


      private void processVideo(){
        videoExecutor.submit(() -> {
            processingVideo.set(true);
            try{

                while(processingVideo.get() && (videoQueue.peek())!=null){

                    final Frame cloneFrame = videoQueue.poll();
                    final Image image = converter.convert(cloneFrame);
                    final long timeStampDeltaMicros = cloneFrame.timestamp - timer.elapsedMicros();
                    if (timeStampDeltaMicros > 0) {
                        final long delayMillis = timeStampDeltaMicros / 1000L;
                        try {
                            Thread.sleep(delayMillis);
                        } catch (InterruptedException e) {
                            Thread.currentThread().interrupt();
                        }
                    }

                    cloneFrame.close();
                    System.out.println("submitted image");
                videoListener.submitData(image);
                }
            }catch (NullPointerException e){
                NullPointerException ex = new NullPointerException("Error while processing video frames.");
            videoListener.notifyFailure(ex);
            }

            processingVideo.set(false);

        });
    }


  


  I sent the whole method for a bit more context but realistically speaking the only part that is of real significance is the converter.conver(cloneFrame) ; I used the intelliJ profiler and also the debugger and this is exactly where the problem occurs. When convert is called after doing some stuff it eventually ends up in this method :

  


          public <t extends="extends" buffer="buffer"> void getPixels(int x, int y, int w, int h, WritablePixelFormat<t> pixelformat, T buffer, int scanlineStride) {&#xA;            int fss = this.frame.imageStride;&#xA;            if (this.frame.imageChannels != 3) {&#xA;                throw new UnsupportedOperationException("We only support frames with imageChannels = 3 (BGR)");&#xA;            } else if (!(buffer instanceof ByteBuffer)) {&#xA;                throw new UnsupportedOperationException("We only support bytebuffers at the moment");&#xA;            } else {&#xA;                ByteBuffer bb = (ByteBuffer)buffer;&#xA;                ByteBuffer b = (ByteBuffer)this.frame.image[0];&#xA;&#xA;                for(int i = y; i &lt; y &#x2B; h; &#x2B;&#x2B;i) {&#xA;                    for(int j = x; j &lt; x &#x2B; w; &#x2B;&#x2B;j) {&#xA;                        int base = 3 * j;&#xA;                        bb.put(b.get(fss * i &#x2B; base));&#xA;                        bb.put(b.get(fss * i &#x2B; base &#x2B; 1));&#xA;                        bb.put(b.get(fss * i &#x2B; base &#x2B; 2));&#xA;                        bb.put((byte)-1);&#xA;                    }&#xA;                }&#xA;&#xA;            }&#xA;        }&#xA;</t></t>

  


  Now, everything up until this point is fine. The memory usage is at around 130mb but alas, when execution enters in these 2 for loops that's where the downright stupid memory usage occurs. Every single one of these bb.put calls is netting me around 3 more megabytes of memory usage. By the end of it you can probably guess what happens. Also all of these memory allocations do happen on the stack so I'm assuming that's why my memory usage stops at around 8-8.5 gigabytes otherwise the program would crash (that has also happened, out of memory exception thrown, but it doesn't usually happen, it kind of just lingers at those 8 gigabytes.) Frankly speaking I'm at a bit of a loss. I haven't seen virtually anyone anywhere mention this ever and I ran out of things to try to fix this so I am making this post.

  


  By the way another thing I tried is make the ExecutorService in the same class as the main method and when I submitted there I also didn't have these memory problems.