Lag in timeline when changing speed of clips

[syed_faizans94185385]

Hello members,
I am using Premiere Pro CC 2018 and the problem starts when I increase or decrease the speed / duration of a clip. Let's say I have 10 clips in sequence. I increase the speed / duration of the 3rd clip and decrease the speed / duration in 4th clip, Premiere Pro will play video smoothly till 3rd clip and start lagging from 4th clip and keep playing like that till the 10th clip in program monitor. Exported video works well but this problem bugs me so much. I have to stop playing the sequence and play again to get rid of lag.

My system configuration is:

Asus X299e motherboard

Intel 7820x processor

GeForce 1080Ti GPU

32GB memory

1x eSata SSD for Windows and other programs

1x NVME SSD for Premiere Pro Media Cache and Database files.

CUDA is always enabled in my projects.

Please help. Thanks!

[ Moved from Premiere Clip (mobile app) tp Premiere Pro forum — mod ]

[davidarbor]

Speed changes can be very processor intensive, especially if you choose Optical Flow. When you change the speed do you get a red render bar over your clip? If so, that means it won't play back in real time and you need to preview it (hit "Enter").

Your machine specs look good, but you didn't say what format or resolution your footage is or what resolution your Program monitor is set to.

If your clips are 4K H.264 and your Program monitor is set to "Full" then I wouldn't expect a speed change with Optical Flow would play back in real time. That information matters just as much as your machine specs.

[syed_faizans94185385]

Hello David, thanks for taking your time to reply me. I am working on A7s II MP4 files with 1920x1080 resolution. Honestly I am very illiterate about Premiere Pro technical stuff. Do you think that enabling Optical Flow causing me this headache? How can I disable it?

[davidarbor]

Hey there, sorry for the delayed reply, I haven't been getting email notifications from the forum.

Optical Flow will actually create new frames, which is why it's such a render-intensive effect. If you feel that it gives you the best results, then by all means, use it. You just need to render the clip first. Even on a powerful machine I still speed change clips with Optical Flow.

[R Neil Haugen]

To add to David's comments, especially if the media is H.264 long-GOP like most any drone, DSLR or mirror-less camera produces, or is some RAW/CinemaDNG or formal Log format of 4k/up, the you'd really need proxies to get full-speed playback. Or cut to 1/2 or 1/4 resolution in Program monitor as he mentions.

So ... the media matters a lot, as well as any effects you're going to apply besides time remapping. Provide a bit more information, we can give more specific advice.

Neil

[syed_faizans94185385]

Thanks you for your reply. I am working on MP4 files (29.99 fps) S-Log 2. What are proxies? I often warp stabilize some clips, is it something I should avoid? What do you mean to cut resolution to1/2 or 1/4.

Thank you

[R Neil Haugen]

JIm's got a good basic bit of advice especially for that media. Which is undoubtedly long-GOP. That means there's a complete frame every 9-30 frames( i frames ), and in between there are data sets for the pixels that 1) have changed since the last i-frame, 2) will change before the next i-frame (requiring of course that i-frame to be decompressed and decoded plus stored to RAM and recalled for every involved frame) ... or both.

It's incredibly CPU/cores/RAM intensive work. Throw in an NLE's heavy demands on the computer along with it, well .. it's difficult. Which is why making Cineform intraframe proxies works better for playback. Every frame is complete just compressed ... far easier on the computer to play, even though at times the files are bigger than the original media.

Cutting resolution refers to the little item in the lower right corner of the Playback Monitor, where you have the option in drop-downs for Full, 1/2, 1/4, or 1/8th resolution. This can help playback also.

Running that media with warp stabilizer applied can be rough on a computer. Two very heavy processes ... just reading & prepping the media for playback, THEN ... before playing back, applying the complex shifting warp process to it. Sometimes it's wise to run warp on clips, then export that to a 'digital intermediate' codec like Cineform, DNxHD/R or ProRes (later if on Mac only), re-importing that into the project, and using that on the sequence rather than the original clip media.

Especially if you've got other heavy lifting like color correction or video noise reduction to be applied later.

Neil

[Jim_Simon]

I recommend using Cineform proxies for all H.264 media.

Work offline using proxy media |