I have tried every possible command to cut a portion (1-3 mins) of an H.264 mp4 video but it comes out good & bad. My video is 29.97 FPS, 1080p, ~80 minutes, ~3.5 GB, and at ~6200 KB/s bitrate. The problem is that my output starts off without video for 1-2 seconds then continues fine, but the audio starts off at 0 seconds. It plays well synced (audio & video) in any media player, but when using it anywhere else (rendering for production purposes) like in Adobe AE, Media Encoder, or a video converter, the FINAL rendered video starts at 0 secs where the audio started. Therefore, the audio ends up 1-2 seconds ahead and I don't want this. This also happens when trimming a YouTube video online at http://clipconverter.cc
My command is as follows:
ffmpeg -ss 01:19:22.000 -t 00:1:43.000 -i "in.mp4" -acodec copy -vcodec copy out.mp4
I even tried putting the -ss after the -i, but I get the same results. Also, I if already have a video with this issue, what can I do to fix it? What could I also do in Adobe AE for this? This site: https://ubuntuforums.org/showthread.php?t=1824250 says that it needs to be cut at the "keyframes". If so how do I do it in FFmpeg? How do I find them? What are they? I do not intend to EVER re-encode (with -c:v x264), it takes too long and recompresses the video with artifacts.
I have used both static and shared builds of FFmpeg. Also used stable 3.2.2 and ffmpeg-20170112-6596b34-win64-static, no luck.
TLDR: My video I cut in FFMPEG has missing frames (not even black or blank ones) at the beginning and results in unsynched audio/video when finally rendered in any video rendering software.