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• Is there a way to prevent black frames from appearing at the start of a video when using -c:v copy ?

  11 juillet 2023, par MethanE

  My task seems simple. Using ffmpeg in terminal, I'm trying to pass through the exact video settings minus the audio, and i've been successful, except for the fact that the videos start with a frame of black before the actual video plays.

  


  currently using this :

  


  for i in *.*;do ffmpeg -i "$i" -an -c:v copy "${i%.*}_noaudio.mp4";done


  


  My current thought is it may be related to the error I'm getting (the vid still exports), but I'm not certain :
Missing key frame while searching for timestamp : 1001

  


  Input video metadata :

  


  Metadata :
major_brand : XAVC
minor_version : 16785407
compatible_brands : XAVCmp42iso2
creation_time : 2021-09-12T20:13:46.000000Z
Duration : 00:00:17.52, start : 0.000000, bitrate : 107315 kb/s
Stream #0:0(und) : Video : h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 96798 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 47.95 tbc (default)

  


  Googling led me to try not using -c:v copy as there might be a glitch related to h264 keyframes and instead using -c:v libx264 but i really don't want to have to re-encode as I don't want to lose any quality. The file I tried this on went from 135 mb down to 6.

  


  Thanks for your help. Kind of a newb at this.

  


• audio is not exact copy in ffmpeg proxies

  9 mars 2023, par 5Diraptor

  I always work with proxy footage in Premiere Pro, so I have a batch file set up to run any new raw footage through ffmpeg and produce a proxy version. I avoid creating proxies through Premiere Pro as it's slow, I have little control over the output, and often the proxies aren't compressed as much as they could be.

  


  This is the command I run to create proxies. It also overlays a watermark so that it is obvious when proxies are used.

  


  ffmpeg -i "original.MOV" -i "proxy_overlay.png" -filter_complex "overlay=0:0" -crf 20 -c:v libx264 -c:a copy "Proxy/proxy_for_original.mov"


  


  This has always been fine, but I've received some footage to work on from a different camera, and when I create proxies and try to attach them in Premiere Pro, I get the error : "Proxy Media and Full Resolution Media must have matching audio channels."

  


  

  


  When I compare the file properties in Premiere Pro, I see this :

  


  Original :

  


  

  


  Proxy :

  


  

  


  As you can see, the original contains 8x audio tracks and a timecode track, but the proxy version doesn't state this.

  


  I've been working on the ffmpeg command to try and retain the original audio details, but nothing I do seems to work. I thought that the command -c:a copy would copy the audio tracks across without any changes at all. However I can't seem to find a command that creates an exact copy of all audio tracks. Also does the timecode track matter, should I map this to the proxy as well ?

  


• avcodec/fic : Don't copy frame unnecessarily

  23 juin, par Andreas Rheinhardt

  avcodec/fic : Don't copy frame unnecessarily
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/fic.c