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• sws_scale screws up last pixel row in smaller x264 mp4 encoding

  23 juillet 2012, par TheSHEEEP

  I am muxing pictures in the PIX_FMT_ARGB format into an mp4 video.

  All of it works well, except that the last pixel row of the outgoing image is screwed up, in most cases the last row is completely black, sometimes there are other colors, it seems somehow dependant on the machine it runs on.

  I am absolutely sure that the error must be in sws_scale, as I am saving the images before and after the scaling. The input images do not have the error, but after the sws_scale() I save the yuv image and the error is apparent.

  Here is an example :

  Original

  

  Yuvfile (after sws_scale)

  

  At the bottom of the Yuvfile, you will see the black row.

  This is how I do the scaling (it is after the official ffmpeg examples, more or less) :

  static int sws_flags = SWS_FAST_BILINEAR | SWS_ACCURATE_RND;
  
  
  
  if (img_convert_ctx == NULL)
  
  {
  
     img_convert_ctx = sws_getContext( srcWidth, srcHeight,
  
             PIX_FMT_ARGB,
  
             codecContext->width, codecContext->height,
  
             codecContext->pix_fmt,
  
             sws_flags, NULL, NULL, NULL );
  
     if (img_convert_ctx == NULL)
  
     {
  
        av_log(c, AV_LOG_ERROR, "%s","Cannot initialize the conversion context\n");
  
        exit(1);
  
     }
  
  }
  
  fill_image(tmp_picture, pic, pic_size, frame_count, ptr->srcWidth, ptr->srcHeight );
  
  
  
  sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
  
          0, srcHeight, picture->data, picture->linesize);

  I also tried a number of different SWS_ flags, but all yield the same result.

  Could this be a bug in sws_scale or am I doing something wrong ? I am using the latest version of the ffmpeg libraries.

• resolution changed mid video - FFMPEG

  27 août 2012, par user1626099

  I have a source video (mpeg2video) which I'm transcoding to x264. The source contains 2 different programs recorded from TV. One is in 4:3 AR and the other 16:9 AR. When I play the source file through VLC the player correctly changes size to show the video at the correct AR. So far so good.

  When I transcode the conversion process auto detects the AR from the first few frames and then transcodes the whole video using this AR. If the 16:9 section comes first then the whole conversion is done in 16:9 and the 4:3 section looks stretch horizontally. If the 4:3 section is at the start of the source file then the whole transcode is done in 4:3 and the 16:9 section looks squashed horizontally.

  No black bars are ever visible.

  Here's my command :

  nice -n 17 ffmpeg -i source.mpg -acodec libfaac -ar 48000 -ab 192k -async 1 -copyts -vcodec libx264 -b 1250k -threads 2 -level 31 -map 0:0 -map 0:1 -map 0:2 -scodec copy -deinterlace output.mkv

  I don't fully understand what's going on. How do I get the same 'change in AR' mid video in the output file that I have in the input video ?

• convert f4v to mp4 with ffmpeg

  9 août 2013, par Winnie Oldright

  Trying to convert f4v to mp4 with ffmpeg

  This file

  FFmpeg :

  ffmpeg -i input.f4v -vcodec copy -acodec copy output.mp4

  In output i have black screen in video and no sound but track seconds are incrementing properly.

  What i'm doing wrong ? Or maybe i need mpg or some other file type in out put (output file type should supports in android).