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• ffmpeg udp/tcp stream receive frame not same as sent

  21 novembre 2013, par vivienlwt

  I am streaming a video on raspberrypi using command :

  ffmpeg -re -threads 2 -i sample_video.m2v -f mpegts - | \
  
  ffmpeg -f mpegts -i - -c copy -f mpegts udp://192.168.1.100:12345

  The remote PC with 192.168.1.100 uses ffmpeg library to listen to the input stream. For example :

  informat = ffmpeg::av_find_input_format("mpegts");
  
  avformat_open_input(&pFormatCtx, "udp://192.168.1.100:12345", informat, options);

  However, when I compute the hash value of each decoded frame on two sides (i.e. raspberrypi and PC), they DON'T MATCH at all. A weird thing is, among 2000 frames, there are in total 10 frames whose hash value are the same on the sender and receiver side. The match result look like this :

  00000....00011000...00011110000...000

  where 0 indicates non-match and 1 indicates match. The matched frame appeared 2 6 in sequence and appeared rarely while most of the other frames has different hash value.

  The hash is computed on the frame data buffer extracted using avpicture_layout(). On the Pi side, I just stream the video to a local port and there's a local process using the same code to decode and hash the frames :

  ffmpeg -re -threads 2 -i sample_video.m2v -f mpegts - | \
  
  ffmpeg -f mpegts -i - -c copy -f mpegts udp://localhost:12345
  
  ...

  The streaming source raspberry pi, is connected directly to the PC using cable. I don't think it is a packet loss problem. Because, first, I rerun the same process several times and the hash value of the received frames are the same (otherwise the result should be different because packet loss is probabilistic). Secondly, I even try to stream on tcp ://192.168.1.100:12345 (and "tcp ://192.168.1.100:12345 ?listen" on PC), and the received frame hash are still the same - different than the hash result on the Pi.

  So, does anyone know why the streaming to a remote address will yield different decoded frames ? Maybe I am missing some details.

  Thanks in advance !!

• Is there any library in python or can we use FFMPEG to detect the appearance of the lines pattern in video that is shown in the image attached below ? [closed]

  21 septembre 2022, par Shreyas R

  Video defect appearing frame

  


  Hi All,

  


  I am trying to find a way to detect the appearance of this lines pattern embedded in the link below.
If I get any match of this pattern in a video, I need to record that particular timestamp of the video where I got the pattern match.

  


  My idea is to take the image and compare it against the video to find for approximate match percentage. If I get it, then I record that particular timestamp within a .txt file.

  


  Is there any better way to achieve this ?
I think we can use Python or FFMPEG video filters to get a solution for this.

  


  It would really help if anyone can support with a solution. Thanks

  


  Update :
I got a reference where they have proposed a solution similar to my concern.

  


  https://aws.amazon.com/blogs/media/metfc-automatically-compare-two-videos-to-find-common-content/

  


  So we can try to achieve some output from this solution.

  


• FFMPeg Windows C# H264

  21 septembre 2011, par Allen Ho

  I am trying to use SharpFFMpeg

  http://sourceforge.net/projects/sharpffmpeg/

  I found avcodec-52.dll and avformat-52.dll somewhere on the Net...

  When I use SharpFFMpeg and make calls like av_init_packet

  I get PInvoke errors like so

  PInvokeStackImbalance was detected
  Message : A call to PInvoke function 'WpfApplicationFFMpegTest !FFmpegSharp.Interop.FFmpeg::av_init_packet' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

  In a nutshell I am trying to decode H264 and display the incoming stream from a camera...

  Just wondering if anyone has been able to do this succesfully in C# ?

  Thanks