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• convert 16bit grayscale raw video by ffmpeg for analysis in openCV

  15 février 2015, par user3730845

  I have 16bit grayscale stream of scientific data which I want to analyse in openCV. I tried to look for some conversion of data, however it seems that grayscale is a trouble for ffmpeg and available codecs.

  My idea is to use 3 colours of video wisely and stream my grayscales into 3 colours, one by one and then in openCV access each colour and do my analysis there. Is such a thing possible ?

  When I convert stream by : ffmpeg -f rawvideo -y -s 256x256 -pix_fmt gray16be -i rawfile.bin -an -vcodec ffv1 video.avi, I get weird colour space but I can open the result in openCV.

  If there is any other way to do such a thing can you point me towards libraries/howtos, ultimately I need to do thresholding, cross-correlation, edge filtering, centre of gravity types of functions and I need to do this as quickly as possible for datasets of >10GB

  My raw files/streams are set of 256x256 16bit b&w images, with 256 bytes header and gaps

• ffmpeg continue streaming to twitch use case

  11 juin 2023, par Hassan M. Amin

  So I have a weird use case that I'm struggling with. Here's the situation :

  


  I have 2 video files, each 1 hour long. I want to stream the first file to twitch in a process, and when that file ends, the ffmpeg process will end and then I want to pickup the other video and continue the stream with that one.

  


  Why should the process end ? because after the first video ends, I need to check via code if the 2nd video is available to be streamed, otherwise I'll re-stream the first video again.

  


  I understand that this can be done via concatenating the two videos, but again, the 2nd video might not be available just yet so we need to end the process right after the 1st video ends streaming and check if it's there.

  


  This works great on YouTube, but the issue I'm facing is that Twitch specifically, when we start streaming the 2nd video, thinks that it's a totally new live stream and resets the live duration counter.

  


  Here's the million dollar question : How can we make twitch think that the data being sent from the 2nd video is the remainder of the first video ? I think it has something to do with the timestamps being sent ? any pointers or other way to look at this ?

  


  Tried updating the pts to be the previous video length + current pts

  


• How to convert a UDP stream to RTMP with FFmpeg ?

  20 avril 2020, par John Riselvato

  It seems the webcam on a macOS streams data via MPEG files which works great with UDP but I want to use this stream for YouTube which only accepts RTMP. Here's what my script looks like based on the documentation :

  



  $ ffmpeg -f avfoundation -framerate 30 -i "0" -f FLV "/"


  



  Which Youtube indicates isn't getting any data from it. 
 have found some weird hack that actually lets me stream my webcam but it's totally non-traditional. If I stream loop an input (input.mp4) an infinite amount of times and apply a random filter, my webcam streams unaffected. I don't see input.mp4 nor is the hue applied to the webcam. It's totally strange.

  



  $ ffmpeg -f avfoundation -framerate 30 -i "0" -stream_loop -1 -i input.mp4 -filter_complex "hue=H=0" -f FLV "$YOUTUBE_URL/$KEY"


  



  So I'm thinking, it has to be a UDP issue and I just need a better way to convert the stream to RTMP. Any thoughts ?