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• 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.

  


• How to use gstreamer to save webcam video to file ?

  2 mars 2015, par sav

  I’ve been trying to get emgu to save same webcam video to file

  The problem is opencv only ssupports avi, and avi does not seem to suit a format like X264 very well.

  Could I use Gstreamer to do this for me in C ?

  It would be good if I could choose the file format and container type too. It would be good if I could use a format like schrodinger dirac.

  I’m new to GStreamer so I’m not quite sure if I’m on the right track here.

  EDIT

  I’ve managed to capture the webcam video using

  gst-launch-0.10 ksvideosrc ! autovideosink

  Now how to transcode this to a format like H264 or dirac ...?

  EDIT

  gst-launch-0.10 ksvideosrc num-buffers=10 ! decodebin2 !
  ffmpegcolorspace ! x264enc ! matroskamux ! filesink
  location=video.mkv

  This seems to create a file, but VLC player can’t read it.

• How to use gstreamer to save webcam video to file ?

  21 juin 2017, par sav

  I’ve been trying to get emgu to save same webcam video to file

  The problem is opencv only ssupports avi, and avi does not seem to suit a format like X264 very well.

  Could I use Gstreamer to do this for me in C ?

  It would be good if I could choose the file format and container type too. It would be good if I could use a format like schrodinger dirac.

  I’m new to GStreamer so I’m not quite sure if I’m on the right track here.

  EDIT

  I’ve managed to capture the webcam video using

  gst-launch-0.10 ksvideosrc ! autovideosink

  Now how to transcode this to a format like H264 or dirac ...?

  EDIT

  gst-launch-0.10 ksvideosrc num-buffers=10 ! decodebin2 !
  ffmpegcolorspace ! x264enc ! matroskamux ! filesink
  location=video.mkv

  This seems to create a file, but VLC player can’t read it.