@AAProds

Hi Al.

What happened after you saved the project and re-opened it?

Did you try having the sound track on a separate track or with the video track?

You have to use your CPU only correct?

Ray.

@CubeAce

Did you try having the sound track on a separate track or with the video track?

Ray, it was the video audio (I kept it grouped with the video, including when I did the cut-speedup.).

If I put in another audio track, what happens to it during the sped-up video? Is it to be sped-up too, because obviously it will be out of sync after the speed comes back).

What happened after you saved the project and re-opened it?

Didn't save it, I'll do that soon.

You have to use your CPU only correct?

Yes.

@AAProds

Hi Al.

Thanks for the info. The sound track should still be linked and kept in sync to the video if put onto a separate track unless the broken chain icon is used to separate the tracks and does, at least at first, do that. On subsequent playbacks or after the project plays is when the problems start. Audio block no longer follow the video track sometimes playing out of order or the wrong speed at the wrong point of the video. Please view all the videos I put up prior. The sound track is even saved completely wrong. At least it is at my end.

Ray.

@jjgrober, @CubeAce

Hi

After some testing with VPX 13 v19.0.2.150, using the speed effect on a finished video clip from another project I keyframed the Speed effect as shown below, note there are no edits to the recording.

I can replicate the syncing issue - if you do not wish to see/hear the first 2 speed ramp up/downs added, jump to 1:40 in the clip below and watch to the end.

However I could not replicate the audio dropping issue either before or after saving/reloading the project.

Looks like the sync issue is a bug.

Ray - the recordings in your last post are very blurred at 1080 HD - is this YT messing up the video or an OBS recording?

John EB

@johnebaker

Hi John.

All I can say is the YouTube videos are showing up as sharp as the files on my PC which are as sharp as running MEP or VPX.

Your video link is just spinning and not showing.

Ray.

@johnebaker

Hi John.

Your video is now showing.

Try splitting the audio file into two mono tracks to simulate the @jjgrober video that has more than one sound source on the same video file.

[Edit] There are two telltale clicks at the very beginning of the video that could be the start of the audio scrambling if pushed further by splitting the stereo track. Very nicely exposed footage and imagery by the way.

Ray.

@johnebaker @CubeAce

Ray's blurred video: shoulda uploaded at 1440P, woulda got VP9 then! 😃

Concur with Ray, can't watch your video properly, John, as it's buffering too much. Better drop that bitrate a tad! 😄.

@AAProds

Hi Alwyn

. . . . it's buffering too much.  . . . .

It was a very smooth ride 😂.

. . . . Better drop that bitrate a tad! . . . .

The video has been re-encoded after uploading to a lowly 4.2 Mb/s and a GOP length of 4, which is too high, the original upload was 14.9 Mb/s and a GOP length of 100.

Forgot to mention there is also the duplicated section near the end on the last speed ramp down.

John EB

@CubeAce I have a 4K clip with a couple of street performers playing violin and cello.

I split the clip into different sections and sped up, slowed down and left one portion of the clip alone. No issues during timeline playback with MEP2022.

The audio was perfect. Maybe a small sample of an original clip to test?

@CubeAce

Hi Ray

. . . . Try splitting the audio file into two mono tracks . . . .

Tried that, I also took it to the extreme - split all audio channels to mono tracks and exported, then added another audio clip- no corruption of audio in any of the preview playbacks or exports, just the sync issue.

Out of interest my audio buffer sizes are 4, 16384 and 4096 respectively

John EB

@AAProds @Reyfox @jjgrober @johnebaker

Hi John.

I have the same number of buffers and samples.

Interesting to note we all have different systems and are getting different results. I don't think the file types matter any more. I think this is a purely a software hardware problem.

There is another difference between MEP 2022 and VPX 12 on my system running this test.

Key frames are not showing up in the audio tracks in the main Key Frame Editor in MEP but are showing up in VPX. Nor can I add any to the audio track in MEP. Yet they show in the timeline.

So far I have only altered the speed in any project to exactly X 2 and back. I have not cut any clips.

This is all very odd and random. On my system, placing the cursor somewhere else on the timeline while the track is playing often results in the audio playing at the speed from the prior point of the video where it left, rather than the speed that should have been dictated in the new play position. I have tried varying the Import ,Processing, Export settings to no avail with similar results considering my results vary a lot.

Ray.

Hi Ray

Using MEP 2022 (laptop) and, just to test, MEP 2021 (PC) I do see the Pitch Keyframes of the saved project from VPX 13 (PC).

When you separated the Left/Right channels to mono did you have to extract the audio stream first or was this already done?

I should also mention that the 3 Device options (MEP 2022 and VPX13) are set to the RTX 2060 on both PC and Laptop

John EB

@johnebaker

Hi John

Did you import the VPX 13 project into MEP? I started the project again from scratch for both programs and each alternate setup for MEP.

I extracted the mono files after importing in VPX 12.

Nvidia on all settings is my default starting point for any project in MEP 2022.

Ray.

@CubeAce

Hi Ray

. . . . Did you import the VPX 13 project into MEP? I started the project again from scratch for both programs and each alternate setup for MEP. . . . .

Initially imported the VPX project, however there is an anomaly in MEP 2022, sometimes I get the Pitch keyframes showing, other times not. Also there is no convert to left/right mono option on right click.

John EB

@johnebaker

Hi John.

Yes no additional options for breaking up audio tracks to mono in MEP, still that is half expected I guess.

This is the most infuriatingly consistently inconsistent test I have ever tried looking at.

Ticket has been sent as a possible hardware software related bug.

Ray.

@CubeAce

Hi Ray

It is puzzling, even the most obvious workaround, cutting the video at strategic points and then speeding up the required sections, does not work correctly - al least on the video clip I tested with.

John EB

@johnebaker

Hi John.

The track knows the time-stretch \ resampling audio effect is already in use on the audio track as it won't allow further adjustment by opening it. Looking at the plugin by opening it on the audio track shows it is not active so there could be a separate instance running controlled by the key frames from the video track. I don't know, it's just guess work, trying to figure out how the two must be connected together and why it can lose sync at random times and intervals.

It's definitely one for the programmers.

Ray.

@CubeAce

Hi Ray

With the speed effect it appear to be using either the Tempo/Pitch effect or a hidden tempo/pitch feature for the audio linked to the video. On opening Tempo/Pitch there are no controls and trying to adjust it pops up this dialog.

Tempo/Pitch cannot be keyframed on its own.

. . . . why it can lose sync at random times and intervals. . . . .

A hypothesis - audio has to lead the video by some milliseconds to compensate for light travelling faster than sound, and this is being corrected for when speeding up the video/audio, however the correction over a longer time has the cumulative effect of delaying the audio depending on the length of the section that is sped up - this showed up when I did a short speed up/down and a longer one. In the tests I did the delay was 3 sec and 10 secs delay for the 2 tests.

John EB

@johnebaker

Hi John.

That I never realised. Not even on a solitary audio track with no video attached or coupling it to an existing video.

You can only set one set of values for the whole clip. You cannot do a speed change as you can within a video clip. (although that is also debatable at the moment 😉) This is something that can be done in a DAW and therefore I never gave it any further thought.

At present I feel like a theoretical physicist going through a thought experiment 🤣🤣.

Ray.

Hi Ray

What I am seeing when speeding up sections to 4 x over 250 and 500 frames ie delay is:

for 250 frames delay is 3.5 secs = 14 ms/frame of at 4x speed

for 500 frames , delay is 6.6 secs = 13.2ms/frame of at 4x speed

John EB

@johnebaker

Hi John.

You are using a much longer video than me. I think you are also getting different results.

For me, there is no stable link as to when the audio speeds up or slows down or if indeed it speeds up at all during a cycle of playback. I have had the video play back at x 2 speed where the clip actually starts at normal play speed and then slows down where it should have sped up and ignores other speed change points thereafter. Sometimes the whole video portion playing correctly finishes before the end of the audio portion but the audio portion in the timeline is showing it's normal end point. It's difficult to see what is going on as it is not possible to generate a waveform.

Ray.

Hi Ray

The bigger the video clip the better for testing - the one I am using is 8 min 27 sec long.

. . . . I have had the video play back at x 2 speed where the clip actually starts at normal play speed and then slows down where it should have sped up and ignores other speed change points thereafter.  . . .

I have had that, only to find, for example, when typing 2 it set 0.20 , I have not had ignoring other KF's though

John EB