Recherche avancée

Sur d’autres sites (10244)

• How to extract video clip from larger video based on specific time and duration

  26 juillet 2022, par user19019404

  I have video clips that get created. Each video is recorded for 5 minutes and starts at a time e.g. 10:01:20 to 10:06:19 then the next video from 10:06:20 etc. These videos are recorded at a specific frame rate, be it 5 frames or 30 frames (its dependent on the platform making the recording). The net result is NOT a 5 minute video clip but might be a 2 minute video clip (where everyone moves very quickly in the view as a result of the frame rates). I cannot restrict a 1 to 1 recording as these are generated by external systems.

  


  I need to extract specific portions out of the video. For example I need to extract from 10:03:10 to 10:03:35 (25 seconds). This would equate to 10 seconds into the video up to 14 seconds into the video, in those 4 seconds of video, 25 real world seconds are displayed.

  


  My question is do you have any guidance as to how I can calculate that each second of recording actually means 10 or 12 seconds in real life, therefore go to this frame and record to this frame for example.

  


  I have been looking at cv2.CAP_PROP_FPS to get the video frame rates, CAP_PROP_POS_MSEC and CAP_PROP_FRAME_COUNT and believe the answer might lie there, but not sure.

  


  The thinking being if I work out the frame rate of the video, the total frames then I can divide the one by the other to get to how many frames make up real world seconds (this is where I fail). This way I can run from frame to frame as a result.

  


  Thank you

  


• Declaring Variables in ffmpeg in a batch file

  8 juillet 2020, par John Smith

  So I wanted to declare a variable and then use that variable throughout my ffmpeg commands in a batch file. I've seen another question about using the duration of the video, but I want to be able to change the timecode I want to cut at myself.

  


  However, the problem is I don't think I'm declaring the variable properly because it says it 00:52:00 is unrecognised, this is what I've tried so far.

  


  $timecodeToCut = 00:52:00

rem The following command can be used to trim an mp4 file at a specified position. In this example it copies the first 42 minutes of the input.mp4 file and copies it to the output.mp4 file.
ffmpeg -i input.mp4 -c copy -to $timecodeToCut tmpOutput1.mp4


  


  EDIT :
I found this from another answer, but couldn't find much information on how variables work with ffmpeg. Sorry about that, I'm a beginner when it comes to coding, do you happen to know how I could correct it to use it in a batch file ? I've tried using set timecodeToCut = 00:52:00 and then in place of $timecodeToCut used %timecodeToCut%, but it still gives me an error ?

  


• vulkan_decode : ensure there's at least one context per decode thread

  27 novembre 2024, par Lynne

  vulkan_decode : ensure there's at least one context per decode thread
  Otherwise, what may happen is that 2 threads will both write
  
  into the same context.
  

  • [DH] libavcodec/vulkan_decode.c