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• ffmpeg record change color

  17 mars 2016, par Антон Михайлов

  Im try record video from screen, for write to video file im use ffmpeg(libavcodec). But on result i see other colors, my example :

  AVCodec *codec;
  
  AVCodecContext *c= NULL;
  
  AVStream *video_stream;
  
  AVOutputFormat *out;
  
  AVFormatContext *out_context;
  
  int i, ret, x, y, got_output;
  
  
  
  AVFrame *frame;
  
  AVPacket pkt;
  
  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
  printf("Encode video file %s\n", filename);
  
  
  
  out = av_guess_format(NULL, filename, NULL);
  
  if (!out) {
  
      std::cout << "Could not deduce output format from file extension: using MPEG.\n" << filename << std::endl;
  
      out = av_guess_format("mpeg", filename, NULL);
  
  }
  
  
  
  if (!out) {
  
      std::cout << "Could not find suitable output format\n" << std::endl;
  
      return;
  
  }
  
  
  
  out->video_codec = (AVCodecID)codec_id;
  
  
  
  out_context = avformat_alloc_context();
  
  if (!out_context) {
  
      std::cout << "Memory error\n";
  
      return;
  
  }
  
  
  
  out_context->oformat = out;
  
  
  
  codec = avcodec_find_encoder((AVCodecID)codec_id);
  
  if (!codec) {
  
      fprintf(stderr, "Codec not found\n");
  
      exit(1);
  
  }
  
  
  
  video_stream = avformat_new_stream(out_context, codec);
  
  if (!video_stream) {
  
      std::cout << "Could not alloc stream\n";
  
      return;
  
  }
  
  
  
  c = video_stream->codec;
  
  if (!c) {
  
      fprintf(stderr, "Could not allocate video codec context\n");
  
      exit(1);
  
  }
  
  
  
  c->bit_rate = 20000000;
  
  
  
  c->width = rect_width;
  
  c->height = rect_height;
  
  
  
  c->time_base = (AVRational){1,25};
  
  c->gop_size = 10; 
  
  c->max_b_frames = 1;
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
  if (codec_id == AV_CODEC_ID_H264)
  
      av_opt_set(c->priv_data, "preset", "slow", 0);
  
  
  
  if (avcodec_open2(c, codec, NULL) < 0) {
  
      fprintf(stderr, "Could not open codec\n");
  
      exit(1);
  
  }
  
  
  
  avio_open2(&out_context->pb, filename, AVIO_FLAG_WRITE, NULL, NULL );
  
  
  
  avformat_write_header(out_context, 0);
  
  
  
  frame = av_frame_alloc();
  
  if (!frame) {
  
      fprintf(stderr, "Could not allocate video frame\n");
  
      exit(1);
  
  }
  
  frame->format = c->pix_fmt;
  
  frame->width  = c->width;
  
  frame->height = c->height;
  
  
  
  ret = av_image_alloc(frame->data, frame->linesize, c->width, c->height,
  
                       c->pix_fmt, 32);
  
  if (ret < 0) {
  
      fprintf(stderr, "Could not allocate raw picture buffer\n");
  
      exit(1);
  
  }
  
  
  
  fprintf(stderr, "*0\n");
  
  
  
  SwsContext *m_imageConvertContext = 0;
  
  
  
  fprintf(stderr, "*0.1\n");
  
  
  
  printf("size %3d %5d\n", rect_width, rect_height);
  
  
  
  if ((rect_width % 4 != 0 && rect_width % 8 != 0 && rect_width % 16 != 0)
  
          || (rect_height % 4 != 0 && rect_height % 8 != 0 && rect_height % 16 != 0)) {
  
      fprintf(stderr, "Video size dimensions must be multiple of 4,8 or 16.");
  
      return;
  
  }
  
  
  
  m_imageConvertContext = sws_getCachedContext(m_imageConvertContext, frame->width, frame->height,AV_PIX_FMT_0RGB32, frame->width, frame->height, c->pix_fmt, SWS_BILINEAR, NULL, NULL, NULL);
  
  
  
  fprintf(stderr, "*0.2\n");
  
  
  
  int pts = 0;
  
  
  
  for (i = 0; i < 25 * 20; i++) {
  
  
  
      QImage image = QGuiApplication::primaryScreen()->grabWindow(0, rect_x, rect_y, rect_width, rect_height).toImage().convertToFormat(QImage::Format_RGB32);
  
  
  
  
  
      pts ++;
  
  
  
      av_init_packet(&pkt);
  
      pkt.data = NULL;    // packet data will be allocated by the encoder
  
      pkt.size = 0;
  
      fflush(stdout);
  
  
  
      uint8_t *srcplanes[AV_NUM_DATA_POINTERS];
  
      srcplanes[0]=(uint8_t*)image.bits();
  
      srcplanes[1]=0;
  
      srcplanes[2]=0;
  
      srcplanes[3]=0;
  
      srcplanes[4]=0;
  
      srcplanes[5]=0;
  
      srcplanes[6]=0;
  
      srcplanes[7]=0;
  
  
  
      int srcstride[AV_NUM_DATA_POINTERS];
  
      srcstride[0]=image.bytesPerLine();
  
      srcstride[1]=0;
  
      srcstride[2]=0;
  
      srcstride[3]=0;
  
      srcstride[4]=0;
  
      srcstride[5]=0;
  
      srcstride[6]=0;
  
      srcstride[7]=0;
  
  
  
      int res = sws_scale(m_imageConvertContext, srcplanes, srcstride, 0,frame->height, frame->data, frame->linesize);
  
  
  
      frame->pts = pts;
  
      ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          av_write_frame(out_context,&pkt);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  for (got_output = 1; got_output; i++) {
  
      fflush(stdout);
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          av_interleaved_write_frame(out_context, &pkt);
  
          av_free_packet(&pkt);
  
      }
  
  }
  
  
  
  av_write_trailer(out_context);
  
  avio_close(out_context->pb);
  
  avcodec_close(c);
  
  
  
  av_free(c);
  
  av_freep(&frame->data[0]);
  
  av_frame_free(&frame);

  resolution 1920x1080. On original display look this http://joxi.ru/p27bbn6u093elm

  on save video colors is a dimmer http://joxi.ru/YmE99W1fZvbdWm

  It seems, white background color changes to gray. Or may be it is brightness. What im do is wrong ? How i can save to color ?

  UDP

  im try use

  int *inv_table, srcRange, *table, dstRange , brightness, contrast, saturation;
  
  
  
  int ret = sws_getColorspaceDetails(m_imageConvertContext, &inv_table, &srcRange, &table, &dstRange, &brightness, &contrast, &saturation);
  
  
  
  sws_setColorspaceDetails(m_imageConvertContext, sws_getCoefficients(SWS_CS_DEFAULT), srcRange, sws_getCoefficients(SWS_CS_ITU709), dstRange, brightness, contrast, saturation);

  but this is never change

• lavfi/vf_ssim : add warning when color ranges differ

  1er avril 2023, par Chema Gonzalez

  lavfi/vf_ssim : add warning when color ranges differ
  The SSIM filter uses the pixel values without considering
  
  the color ranges. This is incorrect. Patch adds a warning
  
  so at least the user knows it.
  Let's see an example.
  (1) Let's get FR and LR versions of the same image.
  ```
  
  $ ffmpeg -y -i /tmp/lena.490x490.ppm -vf scale="out_range=full" -pix_fmt yuv420p /tmp/lena.full.y4m
  
  $ xxd /tmp/lena.full.y4m |head
  
  00000000 : 5955 5634 4d50 4547 3220 5734 3930 2048  YUV4MPEG2 W490 H
  
  00000010 : 3439 3020 4632 353a 3120 4970 2041 303a  490 F25:1 Ip A0 :
  
  00000020 : 3020 4334 3230 6a70 6567 2058 5953 4353  0 C420jpeg XYSCS
  
  00000030 : 533d 3432 304a 5045 4720 5843 4f4c 4f52  S=420JPEG XCOLOR
  
  00000040 : 5241 4e47 453d 4655 4c4c 0a46 5241 4d45  RANGE=FULL.FRAME
  
  00000050 : 0a72 7271 7070 706f 6f6e 6d6d 6c6d 6d6d  .rrqpppoonmmlmmm
  
  00000060 : 6c6e 6e6d 6d6e 6e6e 6d6c 6d6d 6d6d 6d6d  lnnmmnnnmlmmmmmm
  
  00000070 : 6d6e 6d6b 6c6d 6e6e 6d6c 6d6d 6e6e 6f6f  mnmklmnnmlmmnnoo
  
  00000080 : 6f6f 6e6e 6e6e 6f70 7172 7375 7676 7370  oonnnnopqrsuvvsp
  
  00000090 : 6d69 6662 5e59 534d 4845 3d35 302e 2d2c  mifb^YSMHE=50.-,
  
  ```
  ```
  
  $ ffmpeg -y -i /tmp/lena.490x490.ppm -vf scale="out_range=limited" -pix_fmt yuv420p /tmp/lena.limited.y4m
  
  $ xxd /tmp/lena.limited.y4m | head
  
  00000000 : 5955 5634 4d50 4547 3220 5734 3930 2048  YUV4MPEG2 W490 H
  
  00000010 : 3439 3020 4632 353a 3120 4970 2041 303a  490 F25:1 Ip A0 :
  
  00000020 : 3020 4334 3230 6a70 6567 2058 5953 4353  0 C420jpeg XYSCS
  
  00000030 : 533d 3432 304a 5045 4720 5843 4f4c 4f52  S=420JPEG XCOLOR
  
  00000040 : 5241 4e47 453d 4c49 4d49 5445 440a 4652  RANGE=LIMITED.FR
  
  00000050 : 414d 450a 7272 7170 7070 6f6f 6e6e 6e6d  AME.rrqpppoonnnm
  
  00000060 : 6e6e 6e6d 6f6e 6e6e 6e6e 6e6e 6d6e 6e6e  nnnmonnnnnnnmnnn
  
  00000070 : 6e6e 6e6e 6f6e 6c6d 6e6f 6e6e 6d6e 6e6f  nnnnonlmnonnmnno
  
  00000080 : 6f6f 6f6f 6f6f 6f6f 6f6f 7071 7273 7576  oooooooooopqrsuv
  
  00000090 : 7673 706e 6a68 6461 5c57 524e 4b44 3d39  vspnjhda\WRNKD=9
  
  ```
  Note that the 2x images are the same. Only difference is the range,
  
  and the precision issues related to range conversion.
  (2) Let's calculate the SSIM score :
  
  ```
  
  $ ./ffmpeg -filter_threads 1 -filter_complex_threads 1 -i /tmp/lena.full.y4m -i /tmp/lena.limited.y4m -lavfi "ssim" -f null -
  
  ...
  
  [Parsed_ssim_0 @ 0x360ab00] SSIM Y:0.942347 (12.391801) U:0.995808 (23.776062) V:0.996104 (24.093747) All:0.960217 (14.003012)
  
  ```
  As we are comparing an image with itself, we expect "Y : 1" as the
  
  luma SSIM. Issue here is that the SSIM filter just uses the pixel
  
  values, ignoring the color ranges.
  Proposed solution is to add a warning.
  
  ```
  
  $ ./ffmpeg -filter_threads 1 -filter_complex_threads 1 -i /tmp/foo.full.y4m -i /tmp/foo.limited.y4m -lavfi "ssim" -f null -
  
  ...
  
  [Parsed_ssim_0 @ 0x3766280] master and reference frames use different color ranges (pc != tv)
  
  ...
  
  [Parsed_ssim_0 @ 0x3766280] SSIM Y:0.000000 (0.000000) U:0.000000 (0.000000) V:0.000000 (0.000000) All:0.000000 (0.000000)
  
  ```
  Tested :
  Ran fate.
  
  ```
  
  $ make fate -j
  
  ...
  
  TEST    seek-lavf-ppmpipe
  
  TEST    seek-lavf-pgmpipe
  
  TEST    seek-lavf-mxf_opatom
  
  ```
  

  • [DH] libavfilter/vf_ssim.c

• vf_colorspace : Interpret unspecified color range as limited range

  19 septembre 2016, par Vittorio Giovara

  vf_colorspace : Interpret unspecified color range as limited range
  This is the assumption that is made in pixel format conversion do
  
  throughout the code (in particular swscale), and BT-specifications
  
  mandate.
  Add a warning to inform the user that an automatic selection is being
  
  made.
  Signed-off-by : Vittorio Giovara <vittorio.giovara@gmail.com>
  
  Signed-off-by : Ronald S. Bultje <rsbultje@gmail.com>
  

  • [DH] libavfilter/vf_colorspace.c