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• Can I create a VFR video from timestamped images ?

  28 août 2023, par Beginner

  First, I have almost zero experience in making videos from images.

  



  What I have is a set of BMP timestamped images from which I want to generate a video.
Since the timestamps are not equally spaced, I cannot simply use software that create constant-frame-rate videos from images.

  



  A possible solution would be to create artificial images at fixed time intervals, but I prefer to leave that as a last resort if I fail to make a VFR video.

  



  Any suggestions on how to achieve what I want ?

  


• Can I create a VFR video from timestamped images ?

  18 juin 2016, par Beginner

  First, I have almost zero experience in making videos from images.

  What I have is a set of BMP timestamped images from which I want to generate a video.
  Since the timestamps are not equally spaced, I cannot simply use software that create constant-frame-rate videos from images.

  A possible solution would be to create artificial images at fixed time intervals, but I prefer to leave that as a last resort if I fail to make a VFR video.

  Any suggestions on how to achieve what I want ?

• Create drawbox with ffmpeg between specific seconds (without reencoding whole video - faster)

  31 mars 2022, par protter

  My plan was to put a transparent red box behind a video. This box should only be present from second 1-45.
But if the videos are 3 hours long, the process takes a long time although it only has to process 45 seconds.

  


  My first attempt takes too long :

  


  ffmpeg -i %1 -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red@0.5:enable='between(t,1,45)' "%~dp0transpred\%~n1%~x1

  


  Then i tried splitting the video into two parts. put the box on the first video, and then put the two back together again.

  


  ffmpeg  -ss 00:00:00.0000 -i %1 -to 00:00:45.0000  -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red@0.5:enable='between(t,1,45)' "%~dp0transpred\%~n1A%~x1"

  


  FFMpeg -ss 00:00:45.0000 -i %1 -c:v copy -c:a copy -avoid_negative_ts make_zero "%~dp0transpred\%~n1B%~x1"

  


  But i don't even have to try to put these two together, because they are not separated exactly at the second. I have read that this is due to "timestamps" and the different video and audio streams.

  


  Now I'm trying an approach to create a stream with the bar, and then overlay it with the finished video. I haven't quite managed that yet, and I don't know if it's faster.
Shortening the video is very fast.

  


  EDIT (Added as a replacement for the comment later)

  


  Thanks for your help I have almost done it with a slightly different approach. Unfortunately, the second part now always has no sound. No matter if I put A and B (B no sound) or B and A (A no sound) together.

  


  

  1. First split with mkvmerge so i have no worrys about the keyframes and get the exact time
mkvmerge --split timestamps:00:00:45.100 A.MKV -o splitmkm.mkv

  


  2. Then add the Bar (Black because of easier testing) :
ffmpeg -i splitmkm-001.mkv -vf drawbox=0:9*ih/10:iw:ih/10:t=fill BAR1.MKV

  


  3. Merge (mkvmerge ends with error) :
ffmpeg -safe 0 -f concat -i list.txt -c copy output1.mkv

  


  


  EDIT (Answer to kesh)

  


  This was the error Again, audio codec config's must match across all your concat files. The drawbox changed the audio Codec from AC-3 to Vorbis.

  


  the procedure is now :

  


  

  1. mkvtoolnix\mkvmerge --split timestamps:00:00:05.100  %1 -o A_splitmkm.mkv with mkvmerge i have an exact split at the time, and i don't have to learn about keyframes.

  


  2. ffmpeg -i A_splitmkm-001.mkv -vf drawbox=0:9*ih/10:iw:ih/10:t=fill:color=red A_BARmkm.MKV create the Bar

  


  3. ffmpeg -i A_BARmkm.MKV -i A_splitmkm-001.mkv -map 0:v  -map 1 -map -1:v  -c copy A_BARwithAudio.mkv redo the step with the changed audio from drawbox

  


  4. ffmpeg -safe 0 -f concat -i list.txt -map 0  -c copy A_output1.mkv merge

  


  


  Now everything works.
Thanks alot !