Recherche avancée

Sur d’autres sites (6146)

• ffmpeg get last x seconds with high accuracy

  12 mars 2018, par rbarab

  I would like to batch process mp4 videos, getting the last x seconds of each and saving them to individual files.
  I need to do this with a very high accuracy, preferably to 0.001 seconds or better.
  Found a related question (FFMPEG : get last 10 seconds) suggesting -sseof, which works great, but as the answer said it’s not completely accurate with stream copy.

  I am trying to match video lengths to the length of a reference video.

  Would I need to re-encode ? Can sseof handle this accurate enough if I specify duration as 00:00:00.000000 (which I get from reference video ffprobe) ?

  Please see related ffprobe -i below, all videos to be processed have this same encoding.

     Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf57.83.100
  
    Duration: 00:00:58.67, start: 0.000000, bitrate: 639 kb/s
  
      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 640x360, 499 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 131 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
  duration=58.673000

  Is there a better way to achieve frame-level accuracy ? As end goal I would need to overlay these videos with 25fps ’frame-level accuracy’.

  Thanks a lot !

• FFMPEG, Extract first frame and hold for 5 seconds

  8 mars 2018, par Nick Weeden

  I’m trying to overlay a 15 second video transition on the beginning of an image sequence (png sequence with an alpha to reveal the image below), which I can do fine with the overlay filter. But I want to hold the first frame of the image sequence for 5 seconds before playing the animation. I’ve tried trim/select but I can’t seem to get it be a duration of 5 seconds, I also can’t seem to concat it back with the other video to do the transition. So my questions are :

  1. How do I get the first frame and hold it for 5 seconds, the method below works but doesn’t seem like the cleanest option ?

  -framerate 30 -t 60.0 -i input1.%04d.jpg -framerate 30 -t 15.0 -i transition1_%03d.png -filter_complex "color=c=red:d=5:s=480x270:r=30[bg] ; [bg][1:v]overlay[transhold] ; [0:v][transhold]overlay=repeatlast=0[out]"

  2. How can I concat that with the original before I overlay it on the main video, I can do it with two overlays with the start of the actual transition offset by the length of the hold using the command below, but it seems a bit clunky.

  -framerate 30 -t 60.0 -i input1.%04d.jpg -framerate 30 -t 15.0 -i transition1_%03d.png -filter_complex "color=c=red:d=5:s=480x270:r=30[bg] ; [1:v]split[trans][transhold] ; [trans]setpts=PTS+5/TB[trans] ;[transhold]select=eq(n\0)[transhold] ;[bg][transhold]overlay[transhold] ; [0:v][transhold]overlay=repeatlast=0[tmp1] ; [tmp1][trans]overlay[out]"

  This is all part of a larger command where I’m compiling four HD images into a 4k feed each with it’s own transition so the cleaner I can be the better really. I’d also like to be able to vary the duration of the hold for the different HD inputs. If I need to I could bring in the first image as a different input but I would still need to concat them. I thought there must be a way to do this with filters...

• ffplay - Two videos (.mp4), one display screen and just a few seconds to display them together [closed]

  1er juillet 2024, par Gabe Mata

  I have two videos (.mp4), one display screen and just a few seconds to display them together.

  


  I am able to displayed them together on a split screen via ffmpeg and then opening the output file. The problem is that it takes a long time (3 minutes).

  


  Here is the Code : (first code)

  


  ffmpeg -i _20180114094126_flightvideo_cam1.mp4      \
       -i _20180114094126_flightvideo_cam2.mp4       \
       -filter_complex "                              \
               [0:v]crop=1280:360:0:0[v0];             \
               [1:v]scale=1280:-1,crop=1280:360:0:0[v1];\
               [v0] [v1]vstack[v]" \
       -map [v]                     \
       -vcodec libx264               \
       -pix_fmt yuv420p               \
       -preset ultrafast               \
        6000screen_take1.mkv  


  


  On the other hand, when using ffplay I am able to modify one video at the time and play it right away :

  


  $ ffplay -i _20180114094126_flightvideo_cam1.mp4 -vf scale=425:-2 


  


  How can I have the same outcome as the first code above, but display it on my screen right away(without waiting for the output file to be created, 3 minutes in this case) ?

  


  Please let me know if this is not clear.