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• Converted mp4 h264 baseline format loads long time

  10 juillet 2013, par user1830062

  I have converted my video to mp4 x264 baseline format and it works fine with all pc/mobile phones , the problem is it takes long time to load the video while googling came to know that ffmpeg converts and sets the index file at the eof the video so it loads to the end to read and then plays the video, So any advices would be appreciatable to cut short the loading time.
  Note:tryied out QT index swapper2 but dint give much difference , please advice .

  this is the cmd i used to convert -

  ffmpeg -i … -c:v libx264 -profile:v baseline -level 1 …

  Thanks for your time .

• FFMPEG and JNI - pass AVFrame data to Java and Back

  17 octobre 2015, par tishu

  I have some C code that decodes a video frame by frame. I get to a point where i have an AVFrame in BGR32 and would like to send it back to Java for editing.

  I have a ByteBuffer object in my C code that was created in Java using AllocateDirect but i struggle to write the content of the AVFrame->data[0] (of uint8_t type) to it and read it back. I have tried memcpy with no luck. Does anyone have an idea how to achieve this ?

  UPDATE
  Followed Will’s comment below and wrote this in C

  char *buf = (*pEnv)->GetDirectBufferAddress(pEnv, byteBuffer);
  
  memcpy(buf, rgb_frame->data[0], output_width*output_height*4);

  The buffer does contain some data in Java but doing the following returns a null bitmap

  BufferedImage frame = ImageIO.read(bitmapStream);

  Where bitmapStream is a ByteBufferInputStream defined here :
  https://code.google.com/p/kryo/source/browse/trunk/src/com/esotericsoftware/kryo/io/ByteBufferInputStream.java?r=205

  Not sure if I am not writing things correctly in this buffer

  UPDATE 2

  Got pretty close now thanks to the latest snippet. I am using BGR32 format in my C code ie 4 bytes per pixel. So I modified things a bit in Java :

  final byte[] dataArray = new byte[width*height*4];
  
  imageData.get(dataArray);
  
  final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
  
  final DataBuffer buffer = new DataBufferByte(dataArray, dataArray.length);
  
  Raster raster = Raster.createRaster(sampleModel, buffer, null);
  
  image.setData(raster);

  I get the image correctly but there seems to be an issue with color channels
  

  Tried different formats with no luck

• ffmpeg scale down video dynamically (squeeze-back) or zoompan out to smaller than original VER2

  19 juillet 2023, par loarrin

  I have 2 videos, I'm trying to overlay one on top of the other, and have it shrink down in an animated fashion until it appears like a picture-in-picture setup. Then, after a few seconds it should scale back up. Just like in this question. Here is the working code from there :

  


  ffmpeg -i bg.mov -i top.mov -filter_complex "[0:v]scale=1920x1080,setpts=PTS-STARTPTS[bg]; [1:v]setpts=PTS-STARTPTS+2/TB, scale=-1:'480+600*abs(sin((t-2)*2*PI/8))':eval=frame[top]; [bg][top]overlay" -vcodec libx264 out.mp4


  


  It works perfectly, but I have one difference I cannot achieve modifying existing code : scale filter in this example resizes the second video stream having attraction point in the top left corner of this stream. I mean, when the second stream is getting smaller, it is scaled to the top left corner. And if it is getting bigger, it again stretches from the top left corner. The top left corner of the stream being scaled is staying in one place constantly no matter what.

  


  Is it possible to make more symmetrical version of this scale code, so when the second stream is scaled it is scaled from and to the top center of it (So the top left corner would move right when the stream is getting smaller and move to the left then the stream is getting bigger) ?