PeteVanPolaris
When recording as video there seem to a problem with sync in form of duplicate frames. This problem doesn't manifests itself when using f.ex VLC player since VLC is capable of correcting the stream, but if you drop the final video into say Adobe Premiere Pro for post treatment, the problem reveals itself.
In my test case I have a 3 hours video recorded at 29.97 FPS in full HD (1920x1080) at high quality (about 7.7 mb/s on average for video, and 320k/s, 48kHz for audio).
I used ffmpeg to first reencode both audio and video, and not very surprising, this removed the issue.
To check if the problem was with video or audio or both, I then reencoded only video and copied the audio stream as-is. This also fixed the problem, and fortunately this is acceptable since it preserves the audio quality.
The reencoding showed 222 duplicate frame however for the 3 hours video, which here is roughly 7.4 seconds which seem to correspond with the out-of-sync time at the end of the video when using the recorded video directly in Premiere.
I assume the problem derives from having source videos at different frame rates than the recording (retiming). I went through the list of videos I used for this mix and the fps varies from 24.97, 25 (PAL), 29.97 (NTSC) and even 50 fps, in addition to pitch changes etc. Or maybe the problem is related to dropped frames being "corrected"? I'm just guessing.
I hope you can look into the problem to see if there is filter for duplicate frames when recording. As said, I'm able to correct the video stream using ffmpeg, but ideally I would like to avoid this extra step.
Anyways, like the new 2020 version btw. Good job!
Loosely related: could we get advanced options to manually set bitrates for video/audio? It would also be awesome to have non-lossy audio option for the video recording (flac/wav) but you probably would have to offer matroska/mkv container for that..
In my test case I have a 3 hours video recorded at 29.97 FPS in full HD (1920x1080) at high quality (about 7.7 mb/s on average for video, and 320k/s, 48kHz for audio).
I used ffmpeg to first reencode both audio and video, and not very surprising, this removed the issue.
To check if the problem was with video or audio or both, I then reencoded only video and copied the audio stream as-is. This also fixed the problem, and fortunately this is acceptable since it preserves the audio quality.
The reencoding showed 222 duplicate frame however for the 3 hours video, which here is roughly 7.4 seconds which seem to correspond with the out-of-sync time at the end of the video when using the recorded video directly in Premiere.
I assume the problem derives from having source videos at different frame rates than the recording (retiming). I went through the list of videos I used for this mix and the fps varies from 24.97, 25 (PAL), 29.97 (NTSC) and even 50 fps, in addition to pitch changes etc. Or maybe the problem is related to dropped frames being "corrected"? I'm just guessing.
I hope you can look into the problem to see if there is filter for duplicate frames when recording. As said, I'm able to correct the video stream using ffmpeg, but ideally I would like to avoid this extra step.
Anyways, like the new 2020 version btw. Good job!
Loosely related: could we get advanced options to manually set bitrates for video/audio? It would also be awesome to have non-lossy audio option for the video recording (flac/wav) but you probably would have to offer matroska/mkv container for that..
发表时间 Mon 07 Oct 19 @ 10:52 pm