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• FFmpeg cannot extract correct first frame - always extract the second frame [closed]

  21 octobre 2024, par Cai Yu

  I am on macos Ventura 13.2.1, on Macbook Pro M1Max.

  


  The video is number counting animation video. From 2 to 125. The number on first frame is 2. The number on last frame is 125. The number plus one on each frame. You can download the video here.

  


  NOTE that :
First, you hit space bar to play it in Finder, you can see the first frame of the video is number 2.

  


  Second, in professional Video editing software - davinci resolve, on the timeline, you can see the first frame is number 2.

  


  Now I try to use FFmpeg to extract the first frame of the video.
First Try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -vframes 1 /Users/chris/Downloads/1.png


  


  The output png image is number 3. So it's actually the second frame.

  


  Second try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -frames:v 1 /Users/chris/Downloads/1.png


  


  The output png image is still the second frame - the number 3.

  


  Third try :

  


  ffmpeg -i /Users/chris/Downloads/2to125.mov -vf "select=eq(n\,0)" -q:v 3 /Users/chris/Downloads/1.png


  


  The output image is sitll the wrong second frame.

  


  NOTE that :

  


  first : all these three method are from internet. And a lot of people voted correct answer for this question.

  


  second : all their output on my system is the incorrect second frame, not the first frame.

  


  I cannot find what's wrong. Hope friend here help me.

  


• speed up the video and audio 1.5 times ffmpeg [duplicate]

  23 février 2021, par Mayank Thapliyal

  I have a video which I want to speed up 1.5 times. I gave a check on stackoverflow but I did not got the perfect answer for me (sometimes audio disappears,sometimes audio remains unaffected). I want to speed up my video(including audio) 1.5 times.

  


  Also,if possible, can the command be combined with this command into a single command(I guess it would save my processing time)

  


  ffmpeg -i video$.mp4 -filter_complex "[0]crop=iw:ih/2:0:0[top];[0]crop=iw:ih/2:0:oh[bottom];[top][bottom]hstack" -preset fast -c:a copy video.mp4

  


  Thanks in advance

  


• FFMPEG improve MP4 encoding speed [on hold]

  17 septembre 2015, par Kim T

  My input files are MP4, which are combined with an overlay to one MP4 video file. How can I improve the speed of these FFMPEG commands ?

  ./ffmpeg -y -i intro.mp4 -f mpegts 0.ts
  
  ./ffmpeg -y -i record.mp4 -i overlay.png -filter_complex "[0:v][1:v] overlay=0:0" -ac 2 -f mpegts 1.ts
  
  ./ffmpeg -y -i outro.mp4 -f mpegts 2.ts
  
  ./ffmpeg -y -i "concat:0.ts|1.ts|2.ts" -vcodec libx264 -preset ultrafast -strict -2 output.mp4

  Commands that improved speed :

  • upgrading ffmpeg to version 2.42 with neon support for my device
  • -f mpegts = converts videos to transport streams which process faster
  • -preset ultrafast = tells encoder to use fastest encoding preset
  • -ss before -i = seeks straight to start point without processing frames

  Commands where I saw no speed improvement :

  • -c copy = copies the stream, but this doesn’t seem to work on overlay filters and concats :(
  • -threads 2 = tells FFMPEG to use more threads, but don’t noticed an improvement over the default