Clip plays in clip mode, but shows only first frame image in

[Davidk]

One of my video students yesterday drew my attention to an odd occurrence in one of her project files.
A clip - one of several - plays OK in clip mode: video and audio. When switched to project mode, that clip displays only the first frame image of the clip (effectively, a still photo), but the audio plays normally. The vsp has been saved, VS closed, re-opened, vsp opened again, and the same thing happens on that clip. On other clips, no issues.

Why did/does this happen?

Platform is a laptop running windows 10, and the VS version is X8 Pro.

Davidk

[Ken Berry]

... and the video has what properties? And Project Settings are...? I ask because I have just been doing a project with 4K video in relation to another question on this forum. My computer is not up to the job of dealing with 4 K. It plays the 4K jerkily in Clip mode, and much the same as you describe in Project mode. Now I am not suggesting that this clip you have might be 4K. But all I am suggesting it might be in some format that your student's computer has difficulty with...

[Davidk]

Ken,
My experience has been that there are 2 issues with jerky playing. In the main, it's caused by the program playing the file faster than the PC hardware can refill the cache with the next lot of clip data from the memory store. Especially evident when using external memories like usb sticks or cards.
1. One is the actual data interface - between the clip to be played and the processor memory cache. I've found that this can be a real problem - even when playing an SDHC card. If the clip is on a usb stick, then files on usb2 stick plugged into a usb3 slot will be jerky, and usb3 stick in a usb3 slot will certainly be less jerky but probably it is still evident. SDHC using a #10 card has been the best, so far.

Even when the hardware interface is not an issue, the size of the file can be (no doubt preaching to the converted here): in data terms, HD/mpeg-4 is 4x the size of DVD/mpeg-2, and 4K is 4x the size of mpeg-4 all within the same frame display rate. 4k will choke even a top-end processor unless the hardware is very fast and probably has gazillions of RAM. My dual core, 2.7ghz, 8Gb x64 laptop for example plays an mpg file from an SDHC card readily, no jerks. But playing an mp4 file from the same card, on the same PC, and the audio keeps going but the image is jerky and readily gets out of sync with the sound. That same mp4 file plays happily on an entertainment Blu-ray player/HD screen combo.

In the issue posted however, the clip image is a .mov file, and it isn't jerky. Within the project file, select this clip (well into it, say about 15% into the whole thing) and quite a few clips preceded it without a problem. Clip selected in the timeline, choose the clip mode below the preview window, and it plays fine, no jerks. In the project mode, it is just (apparently) stopped, on the first image of the clip, whilst the voice/sound of the clip keeps on playing. What I saw did not look like the sort of jerky images I have frequently seen with large HD files on external memory: esp since the data for this particular project file was all internal ie on the laptop HDD. Very odd, and hence the post.

Davidk

[lata]

Hi David

There have been reports of this behaviour in the past, going back a few versions tends to be a codec issue, but there are so many different types that Video Editors end up playing catchup with the manufacturers. IPhone/tablet video being the main culprits by using variable frame rates.

So where did the video come from?

Smart proxy has interfered with some video types, if using that try disabling and deleting the appropriate proxy file?

If you can provide a sample then we can also try, but does seem that you have replicated the issue.

Did it play ok for you using X9?

Does the laptop have Quicktime installed?