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• lavc/libopenh264 : Support full range videos in transcoding

  18 avril 2023, par Jun Zhao

  lavc/libopenh264 : Support full range videos in transcoding
  Support full range videos when transcoding, enabled the
  
  YUVJ420P to avoid auto scale from YUVJ420P to YUV420P
  Signed-off-by : Jun Zhao <barryjzhao@tencent.com>
  

  • [DH] libavcodec/libopenh264enc.c

• Capture full-range/lossless rgb frame from capture card that supports NV12 and YUYV output

  13 janvier 2023, par kunal joshi

  I am trying to make a program which captures an image, then i need to compare captured image and the input data which i displayed, both should matc pixel by pixel

  


  Here are the details of my capture card

  


  $ v4l2-ctl —list-formats-ext -d /dev/video0

  


  ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'NV12' (Y/CbCr 4:2:0)
                Size: Discrete 3840x2160
                        Interval: Discrete 0.033s (30.000 fps)
                Size: Discrete 2560x1440
                        Interval: Discrete 0.017s (60.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.017s (60.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.017s (60.000 fps)
        [1]: 'YUYV' (YUYV 4:2:2)
                Size: Discrete 2560x1440
                        Interval: Discrete 0.020s (50.000 fps)
                Size: Discrete 1920x1080
                        Interval: Discrete 0.017s (60.000 fps)
                Size: Discrete 1280x720
                        Interval: Discrete 0.017s (60.000 fps)
                Size: Discrete 640x480
                        Interval: Discrete 0.017s (60.000 fps)
        [2]: '' (30313050-0000-0010-8000-00aa003)
        [3]: '' (e436eb7e-524f-11ce-9f53-0020af0)



  


  $ v4l2-ctl —all

  


  Driver Info:
        Driver name      : uvcvideo
        Card type        : ITE HDMI 4K+ Bridge: ITE HDMI 4
        Bus info         : usb-0000:00:14.0-6
        Driver version   : 5.18.0
        Capabilities     : 0x84a00001
                Video Capture
                Metadata Capture
                Streaming
                Extended Pix Format
                Device Capabilities
        Device Caps      : 0x04200001
                Video Capture
                Streaming
                Extended Pix Format
Priority: 2
Video input : 0 (Camera 1: ok)
Format Video Capture:
        Width/Height      : 1920/1080
        Pixel Format      : 'YUYV' (YUYV 4:2:2)
        Field             : None
        Bytes per Line    : 3840
        Size Image        : 4147200
        Colorspace        : sRGB
        Transfer Function : Rec. 709
        YCbCr/HSV Encoding: Rec. 709
        Quantization      : Default (maps to Limited Range)
        Flags             :
Crop Capability Video Capture:
        Bounds      : Left 0, Top 0, Width 1920, Height 1080
        Default     : Left 0, Top 0, Width 1920, Height 1080
        Pixel Aspect: 1/1
Selection Video Capture: crop_default, Left 0, Top 0, Width 1920, Height 1080, Flags:
Selection Video Capture: crop_bounds, Left 0, Top 0, Width 1920, Height 1080, Flags:
Streaming Parameters Video Capture:
        Capabilities     : timeperframe
        Frames per second: 60.000 (60/1)
        Read buffers     : 0




  


  I have tried using various methods opencv but ffmpeg came the closest

  


  With below command i am able to get good results but not what i want

  


  ffmpeg -y -f v4l2 -pix_fmt NV12 -video_size 1920x1080 -i /dev/video0 -pix_fmt bgra -frames:v 10 webcam%03d.bmp


  


  Reference Image

  


  RGB of Reference image

  


  RGB of captured image

  


  Note :- I am able to capture fine with Aforge on windows, but not with ffmpeg on linux.
Would like to know if anyone has already got solution to this.

  


  Thanks in advance.

  


• avfilter/vf_blackdetect : support full-range YUV

  8 décembre 2022, par Niklas Haas

  avfilter/vf_blackdetect : support full-range YUV
  This filter currently makes the distinction between limited and full
  
  range by testing for the deprecated YUVJ pixel formats at link setup
  
  time. This is deprecated and should be improved to perform the detection
  
  based on the per-frame metadata.
  Rewrite it to calculate the black pixel threshold at the time of
  
  filtering a frame, when metadata about the frame's color range is known.
  
  Doing it this way has the small side benefit of being able to handle
  
  streams with variable metadata, and is not a meaningful performance
  
  cost.
  Signed-off-by : Niklas Haas <git@haasn.dev>
  

  • [DH] libavfilter/vf_blackdetect.c