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• checkasm : x86 : properly save rdx/edx in checked_call()

  16 août 2015, par Henrik Gramner

  checkasm : x86 : properly save rdx/edx in checked_call()
  If the return value doesn’t fit in a single register rdx/edx can in some
  
  cases be used in addition to rax/eax.
  Doesn’t affect any of the existing checkasm tests but might be useful later.
  Also comment the relevant code a bit better.
  

  • [DH] tests/checkasm/x86/checkasm.asm

• FFMPEG - How to save audio stream detached from video to file whithout transcoding

  15 septembre 2015, par Tony Than

  I try to use fwrite() to save audio stream. But, generated file can not be opened.
  At the same time, I also try to use av_frame_write() to write packet. But, it can not write.
  Please help me with this problem. How to write audio stream without transcoding....

  /* open the input file with generic avformat function */
  
  err = avformat_open_input(input_format_context, filename, NULL, NULL);
  
  if (err < 0) {
  
      return err;
  
  }
  
  
  
  /* If not enough info to get the stream parameters, we decode the
  
     first frames to get it. (used in mpeg case for example) */
  
  ret = avformat_find_stream_info(*input_format_context, 0);
  
  if (ret < 0) {
  
      av_log(NULL, AV_LOG_FATAL, "%s: could not find codec parameters\n", filename);
  
      return ret;
  
  }
  
  
  
  /* dump the file content */
  
  av_dump_format(*input_format_context, 0, filename, 0);
  
  
  
  for (size_t i = 0; i < (*input_format_context)->nb_streams; i++) {
  
      AVStream *st = (*input_format_context)->streams[i];
  
      if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          FILE *file = NULL;
  
          file = fopen("C:\\Users\\MyPC\\Downloads\\test.aac", "wb");
  
          AVPacket reading_packet;
  
          av_init_packet(&reading_packet);
  
          while (av_read_frame(*input_format_context, &reading_packet) == 0) {
  
              if (reading_packet.stream_index == (int) i) {
  
              fwrite(reading_packet.data, 1, reading_packet.size, file);
  
              }
  
              av_free_packet(&reading_packet);   
  
          }
  
          fclose(file);
  
  
  
          return 0;
  
      }
  
  }

• Extract jpg images from mp4, crop and save exif

  5 juin 2017, par StevenH

  I am trying to take some dashcam footage, crop it, export 1fps to jpg and then the bit I’m stuck on add exif/file date to match the time & date it would have been taken based on my input video.

  The following command does the crop and export to jpg :

  ffmpeg -i c:\temp\dashcam\vid1.mp4 -vf "crop=2560:1311:0:0, fps=1" c:\temp\dashcam\vid1%03d.jpg

  Can I somehow do this by combining a command with ffprobe.

  Ideally I would also add gpx location data using a matching vid1.gpx but there are plenty of tools to do that bit if I can get jpgs with the correct date and time.

  Any help appreciated, thanks.