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• avformat/matroskadec : don't infer display dimensions when DisplayUnit is not pixels

  7 juillet 2024, par James Almer

  avformat/matroskadec : don't infer display dimensions when DisplayUnit is not pixels
  The spec doesn't define a default value for other values of DisplayUnit.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavformat/matroskadec.c

• How to display a stream of mdat/moof boxes in VLC ? [closed]

  8 juillet 2024, par roacs

  I am trying to display a real-time video stream in VLC. The snag is that the real-time video that is being received is a stream of just the mdat and moof boxes of a fragmented MP4 file that is being recorded elsewhere. The initialization information (ftyp/moov) is not and will never be available in the real-time stream. There is also no audio.

  


  I have access to initialization information (ftyp/moov) of a previously completed file and can use that to aid in the processing/streaming of the real-time mdat/moof boxes.

  


  I am currently extracting the contents of the mdat box, splitting those up and packaging them in 188 byte MPEG-TS packets and multicasting them for VLC to pick up. And just as a shot in the dark, every 50 mdat's I am also packaging the SPS and PPS NALUs from the initialization information of the completed file and multicasting those in one MPEG-TS packet.

  


  Input looks like this :

  


  

  • ...

  


  • mdat 1

  


  • moof 1

  


  • mdat 2

  


  • moof 2

  


  • ...

  


  • mdat N

  


  • moof N

  


  • ...

  


  


  And my output looks like this :

  


  

  • ...

  


  • MPEG-TS 1 containing first 184 bytes of mdat 1

  


  • MPEG-TS 2 containing next 184 bytes of mdat 1

  


  • ...

  


  • MPEG-TS N containing last 184 bytes of mdat 1

  


  • MPEG-TS N+1 containing first 184 bytes of mdat 2

  


  • MPEG-TS N+2 containing next 184 bytes of mdat 2

  


  • ...

  


  • MPEG-TS N+M containing last 184 bytes of mdat 2

  


  • ...

  


  • MPEG-TS containing SPS and PPS NALU

  


  • ...

  


  


  VLC gets the data but no video playback.

  


  How do I process this input in order to get it to play in VLC ?

  


• Not able to display first frame of mp4 file

  23 juin 2024, par Jatin Parmar

  I am learning OpenCV from YouTube, and I just created a very basic program in Python.

  


  import cv2 as cv

sources = cv.VideoCapture("test.mp4");

if not sources.isOpened():
    print("Failed to open video file");
else:
    print("video file opened successfully");

win_name = "test"
cv.namedWindow(win_name)

(has_input, frame) = sources.read()
if has_input:
    cv.imshow(win_name, frame[...,::-1])
    cv.waitKey(0)

sources.release()


  


  But when I run the program, I have the following errors : I have tried Googling it, but I didn't find any working solutions.

  


  [av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
[av1 @ 0x55e6dc8b0780] Missing Sequence Header.
video file opened successfully
[av1 @ 0x55e6dc97a7c0] Your platform doesn't suppport hardware accelerated AV1 decoding.
[av1 @ 0x55e6dc97a7c0] Failed to get pixel format.


  


  here is the link of video
https://drive.google.com/file/d/1TgY5O6pFLU3eEGsvmU0LoAw6_I8kGM6s/view?usp=sharing
I have no idea how to fix this.