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• avformat/matroskaenc : Add support for FlagTextDescriptions

  16 février 2021, par Andreas Rheinhardt

  avformat/matroskaenc : Add support for FlagTextDescriptions
  This is the Matroska equivalent of D_WEBVTT_DESCRIPTIONS and is
  
  therefore only enabled for subtitles.
  Reviewed-by : Ridley Combs <rcombs@rcombs.me>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• How to receive upd stream with OpenCV ?

  17 février 2021, par Legion

  I need to receive my stream from Jetson Nano to my OpenCV program on my PC (Windows 10).

  


  Ok, I stream camera from my device (Jetson Nano) using :

  


  cv::VideoWriter gst_udpsink("appsrc ! video/x-raw, format=BGR ! queue ! videoconvert ! video/x-raw, format=BGRx ! nvvidconv ! nvv4l2h264enc insert-vui=1 ! video/x-h264, stream-format=byte-stream ! h264parse ! rtph264pay pt=96 config-interval=1 ! udpsink host=224.1.1.1 port=5000 auto-multicast=true", cv::CAP_GSTREAMER, 0, fps, cv::Size (width, height));


  


  I installed OpenCV with Gstreamer(following that ) and tried that command

  


  c:\gstreamer\1.0\msvc_x86_64\bin\gst-launch-1.0.exe  udpsrc uri=udp://224.1.1.1:5000 auto-multicast=true ! application/x-rtp, media=video, encoding-name=H264 ! rtpjitterbuffer latency=300 ! rtph264depay ! decodebin ! d3dvideosink


  


  it is working, unfortunately, no matter what latency I set I still got quite a big lag.
When I try to use OpenCV

  


  cv::VideoCapture cap("udpsrc uri=udp://224.1.1.1:5000 auto-multicast=true ! application/x-rtp, media=video, encoding-name=H264 ! rtpjitterbuffer latency=300 ! rtph264depay ! decodebin ! videoconvert ! video/x-raw, format=BGR ! appsink", cv::CAP_GSTREAMER);


  


  I get

  


  [ WARN:0] global F:\Code\opencv_4.5.1\opencv-4.5.1\modules\videoio\src\cap_gstreamer.cpp (734) cv::GStreamerCapture::open OpenCV | GStreamer warning: Error opening bin: no element "udpsrc"
[ WARN:0] global F:\Code\opencv_4.5.1\opencv-4.5.1\modules\videoio\src\cap_gstreamer.cpp (501) cv::GStreamerCapture::isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created


  


  And .isOpened() give me false.
I’m don’t know why did I install something wrong ?

  


  I added everything to my PATH as instructed

  


  

  


  I also tried to use FFmpeg :

  


  setenv ("OPENCV_FFMPEG_CAPTURE_OPTIONS", "protocol_whitelist;file,rtp,udp", 1);
cap = cv::VideoCapture("test.sdp", cv::CAP_FFMPEG);


  


  I get :

  


  [rtp @ 0000014dc1f83bc0] Protocol 'rtp' not on whitelist 'file,crypto,data'!


  


  I have no setenv() so I tried this and it seems that’s a problem, any idea ?

  


  Shell equivalent

  


  ffplay myFile.sdp -protocol_whitelist file,udp,rtp -fflags nobuffer


  


  Is working successfully (with delay but successfully).

  


  I'm willing to change anything to make it work ! If it's possible with FFmpeg/GStreamer/vlclib, I can change the Jetson side as well, thanks for any help !

  


• how to record camera to file while encoding stream to v4l2-loopback device ?

  3 février 2021, par Jonatas

  So i have this logitech c920 camera 1920x1080 h264 capable and i would like to record the camera to file while at the same time copying/encoding the stream to a loopback device so the camera can be still used by other apps.
here is the code i got so far :

  


  ffmpeg -report -f alsa -i hw:CARD=C920,DEV=0 -r 1500 -s 1920x1080 -f v4l2 -vcodec h264 \
-i /dev/video1 -copyinkf -vcodec copy /home/jonatas/Videos/2021-02-01185658.mp4 \ 
-f v4l2 /dev/video0


  


  error :

  


  Unknown V4L2 pixel format equivalent for yuvj420p
Could not write header for output file #1 (incorrect codec parameters ?): Invalid argument
Error initializing output stream 1:0 -- 


  


  some info on /dev/video0(loopbackdevice) :

  


  v4l2-ctl -d /dev/video0

    Device Caps      : 0x05208003
        Video Capture
        Video Output
        Video Memory-to-Memory
        Read/Write
        Streaming
        Extended Pix Format
Priority: 0
Video input : 0 (loopback: ok)
Video output: 0 (loopback in)
Format Video Output:
    Width/Height      : 1280/720
    Pixel Format      : 'YUYV' (YUYV 4:2:2)
    Field             : None
    Bytes per Line    : 2560
    Size Image        : 1843200
    Colorspace        : sRGB
    Transfer Function : Default (maps to sRGB)
    YCbCr/HSV Encoding: Default (maps to ITU-R 601)
    Quantization      : Default (maps to Limited Range)
    Flags             : 
Streaming Parameters Video Capture:
    Frames per second: 30.000 (30/1)
    Read buffers     : 8
Streaming Parameters Video Output:
    Frames per second: 30.000 (30/1)
    Write buffers    : 8

User Controls

                    keep_format 0x0098f900 (bool)   : default=0 value=0
              sustain_framerate 0x0098f901 (bool)   : default=0 value=0
                        timeout 0x0098f902 (int)    : min=0 max=100000 step=1 default=0 value=0
               timeout_image_io 0x0098f903 (bool)   : default=0 value=0


  


  some info on my camera in /dev/video1

  


  v4l2-ctl -d /dev/video1 --all
Driver Info:
    Driver name      : uvcvideo
    Card type        : HD Pro Webcam C920
    Bus info         : usb-0000:00:14.0-7.2
    Driver version   : 5.4.78
    Capabilities     : 0x84a00001
        Video Capture
        Metadata Capture
        Streaming
        Extended Pix Format
        Device Capabilities
    Device Caps      : 0x04200001
        Video Capture
        Streaming
        Extended Pix Format
Media Driver Info:
    Driver name      : uvcvideo
    Model            : HD Pro Webcam C920
    Serial           : EC6C336F
    Bus info         : usb-0000:00:14.0-7.2
    Media version    : 5.4.78
    Hardware revision: 0x00000011 (17)
    Driver version   : 5.4.78
Interface Info:
    ID               : 0x03000002
    Type             : V4L Video
Entity Info:
    ID               : 0x00000001 (1)
    Name             : HD Pro Webcam C920
    Function         : V4L2 I/O
    Flags         : default
    Pad 0x01000007   : 0: Sink
      Link 0x0200001f: from remote pad 0x100000a of entity 'Processing 3': Data, Enabled, Immutable
Priority: 2
Video input : 0 (Camera 1: ok)
Format Video Capture:
    Width/Height      : 1280/720
    Pixel Format      : 'H264' (H.264)
    Field             : None
    Bytes per Line    : 2560
    Size Image        : 1843200
    Colorspace        : sRGB
    Transfer Function : Default (maps to sRGB)
    YCbCr/HSV Encoding: Default (maps to ITU-R 601)
    Quantization      : Default (maps to Full Range)
    Flags             : 
Crop Capability Video Capture:
    Bounds      : Left 0, Top 0, Width 1280, Height 720
    Default     : Left 0, Top 0, Width 1280, Height 720
    Pixel Aspect: 1/1
Selection Video Capture: crop_default, Left 0, Top 0, Width 1280, Height 720, Flags: 
Selection Video Capture: crop_bounds, Left 0, Top 0, Width 1280, Height 720, Flags: 
Streaming Parameters Video Capture:
    Capabilities     : timeperframe
    Frames per second: 30.000 (30/1)
    Read buffers     : 0
                     brightness 0x00980900 (int)    : min=0 max=255 step=1 default=128 value=128
                       contrast 0x00980901 (int)    : min=0 max=255 step=1 default=128 value=128
                     saturation 0x00980902 (int)    : min=0 max=255 step=1 default=128 value=128
 white_balance_temperature_auto 0x0098090c (bool)   : default=1 value=1
                           gain 0x00980913 (int)    : min=0 max=255 step=1 default=0 value=255
           power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=2 value=2
                0: Disabled
                1: 50 Hz
                2: 60 Hz
      white_balance_temperature 0x0098091a (int)    : min=2000 max=6500 step=1 default=4000 value=3233 flags=inactive
                      sharpness 0x0098091b (int)    : min=0 max=255 step=1 default=128 value=128
         backlight_compensation 0x0098091c (int)    : min=0 max=1 step=1 default=0 value=0
                  exposure_auto 0x009a0901 (menu)   : min=0 max=3 default=3 value=3
                1: Manual Mode
                3: Aperture Priority Mode
              exposure_absolute 0x009a0902 (int)    : min=3 max=2047 step=1 default=250 value=333 flags=inactive
         exposure_auto_priority 0x009a0903 (bool)   : default=0 value=0
                   pan_absolute 0x009a0908 (int)    : min=-36000 max=36000 step=3600 default=0 value=0
                  tilt_absolute 0x009a0909 (int)    : min=-36000 max=36000 step=3600 default=0 value=0
                 focus_absolute 0x009a090a (int)    : min=0 max=250 step=5 default=0 value=0
                     focus_auto 0x009a090c (bool)   : default=1 value=0
                  zoom_absolute 0x009a090d (int)    : min=100 max=500 step=1 default=100 value=100


  


  if i remove the 3rd line of my script the camera records the stream of video and sound to the file flawless. i tried diferent things for the 3rd line as -vcodec and something to do with pix-format flag to YUYV without success.
Is it possible to achieve this with just one ffmpeg process ?
Will the sound be made available to the loopback device also ?
How to transcode it to the proper pixel format used by loopback device ?