Stuttering video export (similar to frame-drops)

mrgreenh

Hi! I've recently started trying Mixemergency and loving it so far, really great software. I've encountered one last roadblock to fit it in my workflow, which happens when I export a mix recording: the videos I use involve smooth continuous movement, however in the video export a glitch is introduced. The movement seems to be interrupted by a light jump, similar to a frame drop but which appears similar to a jump back one frame and then forth another frame, very rapid (just enough to be perceivable). This happens at regular time intervals, of about one second. The original video is completely smooth however. The export setting is the highest quality preset, frame blending and antialiasing are enabled. I tried both multi-pass on and off, I tried increasing bitrate from 5 to 20mbps. This shared dropbox folder has both the original video and the respective portion from the Mixemergency export for comparison: https://www.dropbox.com/sh/15koj3t3l190uw8/AAA6FM8Lx4mEeQwGkNu0tOlia?dl=0 I'm using Serato DJ connected to a Denon Prime 4. Macbook Pro 14inch 2021 with Apple M1 Pro, 16GB memory. Latest mixemergency (downloaded it last weekend). I have noticed a similar issue before when I used to encode videos using ffmpeg, which I fixed by adding the "minterpolate" option for movement-based frame interpolation. I wonder if there was a way to make sure the same is used for these video exports, it might fix the issue. Thanks in advance for the help!

Nick

From watching those videos, it looks like the stuttering that you're seeing is caused by a single frame being displayed twice. This is likely because the playback rate of the original video doesn't exactly match that of what you've recorded in MixEmergency (imagine exporting a video that is playing at 29 FPS at 30 FPS - eventually one of those frames will be displayed twice). It looks as though frame-blending is not being correctly added, however - which should minimise this affect, while adding other visual issues. I will have to look into that - though I've also been thinking about removing frame blending altogether. Note that exporting at a higher frame rate (e.g. 60 FPS) should reduce this stuttering effect a little.

mrgreenh

Hi Nick, thank you so much for the prompt reply. I tried exporting the recording to 60fps and it does indeed mitigate the problem a lot! It's still visible but barely, it's no longer perceivable for example by just looking at the grass, and one has to stare attentively at the trees to notice. I think this for now makes the quality acceptable for my use case, thank you so much for your suggestion! Do let me know if you need more information to reproduce the problem if you'll look deeper into it. In my experience so far, it's the only issue that currently visibly affects the quality of the end result which is otherwise really great. Thanks again for your work!

Nick

I'm glad to hear that this helped. Ideally (at least, for the output) we would output at a variable framerate, so that MixEmergency's output only changed when the input video frame changed, but this would likely cause a lot of issue for MixEmergency's effects and transitions.