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• Enable QSV for FFmpeg with directshow input and JPEG image sequence output

  10 mars 2020, par clic

  I’m using FFmpeg with Directshow input. The output is a series of single JPEG images. FFmpeg itself maps the stream to mjpeg and uses image2 for the output.

  Is it possible to increase performance by using the Intel QuickSync Video (QSV) hardware acceleration for this process ? The FFmpeg QuickSync Wiki actually lists JPEG encoding since Braswell.

  This is what I tried so far :

  ffmpeg -init_hw_device qsv=hw -filter_hw_device hw -f dshow -video_size 3840x2160 -framerate 25 -i "video=My Webcam" -vf hwupload=extra_hw_frames=64,format=qsv -vcodec mjpeg_qsv "C:\out\%d.jpg"

  The command works, images are generated - but the GPU load seems to be the same as without any qsv options..?

  Thanks !

• ffmpeg : Concat multiple mp4 with no audible delay between clips

  16 novembre 2014, par Geuis

  I have several dozen mp4 clips that all have the same resolution, codecs, etc. I’m trying to combine them into a single file using ffmpeg, but there always seems to be a slight audio delay between the clips. My problem is that I’d like them to be seamless.

  Been following the steps here, https://trac.ffmpeg.org/wiki/How%20to%20concatenate%20(join,%20merge)%20media%20files

  There’s always a slight delay between the files, which is especially noticeable in the audio.

  Is there a recommended way to merge video files with no delay between them ?

• FFMPEG image resize not working

  8 décembre 2015, par Soundhar Raj

  FFmpeg version 0.6.5 is installed on my web server.

  In my website mp4 videos allowed to upload, that part is done.
  Now i am working on create a thumbnail of the video and then resize it.

  The following links are I referred.

  https://trac.ffmpeg.org/wiki/Create%20a%20thumbnail%20image%20every%20X%20seconds%20of%20the%20video

  https://trac.ffmpeg.org/wiki/Scaling%20(resizing)%20with%20ffmpeg

  This is the command i used to create a thumbnail from video, this command is working.

  $cmd = "ffmpeg -i test.mp4 -ss 0 -vframes 1 out.png";

  After creating the thumbnail, I tried the following the command to resize it, but this is not working.

  $cmd = 'ffmpeg -i out.png -vf scale=210:-1 output_320x240.png';

  And Some other commands i have tried

  $cmd = "ffmpeg -ss 10 -i test.mp4 -vframes 1 -filter scale=-1:150,crop=200:150 output.jpg";
  
  
  
  $cmd = "ffmpeg -itsoffset -1 -i test.mp4 -vframes 1 -filter:v scale=280:-1 output.jpg";

  In my localhost I used the following command to create thumbnail and resize in a single command, but this is also not working in the server.

  $ffmpeg = 'C:\\ffmpeg\\bin\\ffmpeg';
  
  $video = 'test.mp4';
  
  $cmd = "$ffmpeg -itsoffset -1 -i $video -vframes 1 -filter:v scale=\"210:-1\"  thumbnail.png";

  Thanks to all