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• How can I extract the characteristics of multimedia video stream while the video is streaming ?

  10 mai 2021, par Kai

  I have built adaptive video streaming ,DASH, over SDN network and was wondering if I can get some video characteristics while the video is streaming. I have used youtube_dl and was able to get the received video after the completion of the stream however, I want to get the video characteristics such as (stream size, bitrate, frame rate, resolution and etc.) while streaming. I hope that you can provide me with a script to extract and generate a file that contains such information.

  


• How can i stop ffmpeg buffer from streaming ?

  23 juin 2020, par sniper

  I try to obtain a screenshoot for live streaming when websockets announce he need a screenshoot.

  


  At this moment I use this command for a subprocess on python :

  


  command = 'ffmpeg -ss 00:00:01 -i '+str(urllive)+' -vframes 1 -q:v 2 /var/www/html/ai/dist/img/'+str(canlive)+'.png -y'

  


  the script is working very well but this command is a for iteration, and execute the command for 7-12 times in less than 1 second.
The problem is when ffmpeg take the screenshoot start the streaming and take the buffer for this stream.
The buffer stream have around 7MB * 10(iteration) mean 70 MB, and load the network traffic with 70MB*8 = 560Mbps on that second.
How can i disable or reduce the buffer on ffmpeg client ?
  
I tried with bufsize 1M, -fflags nobuffer args but no success.

  


  ffmpeg version 3.4.6

  


• What are my FFMPEG command wrong parameters that causes ugly quality on streaming ?

  6 juillet 2022, par Lucas FAURE

  Good day, I'm scaling videos with FFMPEG, and when the scaled file comes out, quality is pretty good (enough good for me).

  


  My problem is that I'm as well streaming the file while it's scaling, but it comes in an ugly quality. And I guess it's because of missing or not needed parameters.

  


  Here is my command that starts scaling the file and send it via RTMP for streaming :

  


  "ffmpeg -i " + file + " -vf scale=-2:" + resolution + " -preset slow -crf 18 -movflags +frag_keyframe+separate_moof+omit_tfhd_offset+empty_moov " + output + " -listen 1 -f flv rtmp://127.0.0.1:10000/" + stream + ""


  


  This is called in Python, where file is the source file, resolution the new height, output the file to be saved, and stream a streaming key.

  


  Once the scaling has started, I provide to the user a streaming link with the new resolution :

  


  'ffmpeg -v verbose -i rtmp://127.0.0.1:10000/'.$stream.' -c:v libx264 -c:a aac -ac 1 -strict -2 -crf 18 -profile:v baseline -maxrate 400k -bufsize 1835k -pix_fmt yuv420p -flags -global_header -hls_time 10 -hls_list_size 6 -start_number 1 '.$streamURL.$stream;


  


  Here, it's called with PHP, and there are as well variables : stream the streaming key to retreive the right content, and streamURL the domain to visit.

  


  It actually works but the difference of quality between what is scaling and what is streaming is huge, and I think so that, in the command that creates the streaming link, there is parameters that cause this. (Because I took it from a live example and I didn't want to make an error by removing parameters I don't know well)

  


  Do you have any idea about where it can be coming from ?

  


  Thank you in advance for your help and time.