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• sws_scale YUV —> RGB distorted image

  3 janvier 2015, par Sami susu

  I want to convert YUV420P image (received from H.264 stream) to RGB, while also resizing it, using sws_scale.
  The size of the original image is 480 × 800. Just converting with same dimensions works fine.
  But when I try to change the dimensions, I get a distorted image, with the following pattern :

  • changing to 481 × 800 will yield a distorted B&W image which looks like it’s cut in the middle
  • 482 × 800 will be even more distorted
  • 483 × 800 is distorted but in color
  • 484 × 800 is ok (scaled correctly).

  Now this pattern follows - scaling will only work fine if the difference between divides by 4.

  Here’s a sample code of the way that I decode and convert the image. All methods show "success".

  int srcX = 480;
  
  int srcY = 800;
  
  int dstX = 481; // or 482, 483 etc
  
  int dstY = 800;
  
  
  
  AVFrame* avFrameYUV = avcodec_alloc_frame();
  
  avpicture_fill((AVPicture *)avFrameYUV, decoded_yuv_frame, PIX_FMT_YUV420P, srcX , srcY);
  
  
  
  AVFrame *avFrameRGB = avcodec_alloc_frame();
  
  
  
  AVPacket avPacket;
  
  av_init_packet(&avPacket);
  
  avPacket.size = read; // size of raw data
  
  avPacket.data = raw_data; // raw data before decoding to YUV
  
  
  
  int frame_decoded = 0;
  
  int decoded_length = avcodec_decode_video2(g_avCodecContext, avFrameYUV, &frame_decoded, &avPacket);
  
  int size = dstX * dstY * 3;
  
  
  
  struct SwsContext *img_convert_ctx = sws_getContext(srcX, srcY, SOURCE_FORMAT, dstX, dstY, PIX_FMT_BGR24, SWS_BICUBIC, NULL, NULL, NULL);
  
  
  
  avpicture_fill((AVPicture *)avFrameRGB, rgb_frame, PIX_FMT_RGB24, dstX, dstY);
  
  sws_scale(img_convert_ctx, avFrameYUV->data, avFrameYUV->linesize, 0, srcY, avFrameRGB->data, avFrameRGB->linesize);
  
  
  
  // draws the resulting frame with windows BitBlt
  
  DrawBitmap(hdc, dstX, dstY, rgb_frame, size);
  
  
  
  sws_freeContext(img_convert_ctx); 

• x264 & libavcodec

  25 janvier 2012, par moose

  After some considerable amount of time while trying to build the ffmpeg static library with the x264 encoder on Windows, I have spent some more time for writing some example with it.
  Of course, there are tons of "instructions" on how to build, how to use, bla bla... But, non of them works on Windows. I guess the Linux guys are in better position here. Now, the zillion dollars question is "What's the purpose of all that ?". Not only that this is useless on Windows, but I could have bought some third party library that actually works.

  If somebody is about to say "But, it works !". I must say, give me a working proof. I don't care about 200x100 at 10fps. I don't need H264 for that. Show me how to compress a single second of 1080i footage. It's H264, it's crossplatform (sounds funny if you ask me), Google is using it (it has to be perfect, right ?), some more hipe here...

• ffmpeg command line working on emulator but not in device in android

  18 avril 2013, par rams

  i want to convert sequence of images into video.i successfully completed this task in emulator.but in real device its not working.what's the problem.i put the ffmpeg executable files and libraries in system/bin as well as system/lib folder.

  Runtime.getRuntime().exec("chmod 777 /system/bin/ffmpeg");
  
  chperm=Runtime.getRuntime().exec("ffmpeg -f image2 -i img%4d.jpg adi.avi",null,dir);
  
  Toast.makeText(getBaseContext(), "success", Toast.LENGTH_SHORT).show();