Prefetch frames does not seem to take effect on playback #41165

New Issue

Jonata Bolzan · 2014-07-24T14:43:10+02:00

Jonata Bolzan commented

2014-07-24 14:43:10 +02:00

System Information
Mac OS X 10.9.4

Blender Version
Broken: 2.71

Short description of error
Editing a multi-strip project on VSE, I am not able to playback smoothly the sequence.

No matter if I change the value in Blender preferences (System - Seuqnecer/Clip Editor: Prefetch Frames), the playback hangs and even Blender become unresponsive.

By the way, the documentation (http://wiki.blender.org/index.php/Doc:2.6/Manual/Preferences/System) says that there is a limit on "System - Sequencer/Clip Editor" values. If the documentation is updated and this is still applicable, I think the controls of UI should limit the numbers. Should I open another bug for this UI issue?

**System Information** Mac OS X 10.9.4 **Blender Version** Broken: 2.71 **Short description of error** Editing a multi-strip project on VSE, I am not able to playback smoothly the sequence. No matter if I change the value in Blender preferences (System - Seuqnecer/Clip Editor: Prefetch Frames), the playback hangs and even Blender become unresponsive. By the way, the documentation (http://wiki.blender.org/index.php/Doc:2.6/Manual/Preferences/System) says that there is a limit on "System - Sequencer/Clip Editor" values. If the documentation is updated and this is still applicable, I think the controls of UI should limit the numbers. Should I open another bug for this UI issue?

Jonata Bolzan commented

2014-07-24 14:43:10 +02:00

Changed status to: 'Open'

Jonata Bolzan commented

2014-07-24 14:43:10 +02:00

Added subscriber: @jonata

Bastien Montagne commented

2014-07-24 19:55:37 +02:00

Added subscriber: @mont29

Antonis Ryakiotakis was assigned by Sergey Sharybin

2014-07-28 12:47:40 +02:00

Sergey Sharybin commented

2014-07-28 12:47:40 +02:00

Added subscribers: @Psy-Fi, @Sergey

Sergey Sharybin commented

2014-07-28 12:47:40 +02:00

@Psy-Fi, afair this isn't fully ported since 2.49. Mind having a glance?

Antonis Ryakiotakis commented

2014-08-04 13:14:22 +02:00

Quick test with two strips here looks OK...I'd like a test file to investigate if possible.

Jonata Bolzan commented

2014-08-04 15:08:32 +02:00

Well, it is not that hard to reproduce. Just add a lot of strips with common effects like alpha over. The link is for a screen record of some strips playing with some video. The FPS goes to 4-7 - definitely not smooth - and you can note that when you move a strip and play, you can see... how can I say... "residual" frames that, as I understand, is a consequence of blender not pre-"fetching" the frames.

https://www.dropbox.com/s/qbceph71k2xvwot/blender-vse-test.mov

Thanks for the attention.

Well, it is not that hard to reproduce. Just add a lot of strips with common effects like alpha over. The link is for a screen record of some strips playing with some video. The FPS goes to 4-7 - definitely not smooth - and you can note that when you move a strip and play, you can see... how can I say... "residual" frames that, as I understand, is a consequence of blender not pre-"fetching" the frames. https://www.dropbox.com/s/qbceph71k2xvwot/blender-vse-test.mov Thanks for the attention.

Antonis Ryakiotakis commented

2014-08-04 15:38:53 +02:00

This looks like latency due to computation time rather than a hang. Scaling and translating an image just takes time. This is normal.

Jonata Bolzan commented

2014-08-04 15:47:03 +02:00

I see. So, what is "prefetch" for?

Antonis Ryakiotakis commented

2014-08-04 16:05:45 +02:00

Changed status from 'Open' to: 'Archived'

Antonis Ryakiotakis closed this issue

2014-08-04 16:05:45 +02:00

Antonis Ryakiotakis commented

2014-08-04 16:05:45 +02:00

Prefetch fetches the frames of the movie itself in memory, it doesn't influence computation time due to transform operations. In the uploaded video you can clearly see that the delay occurs only while those transforms are active, not due to the movie itself.

Jonata Bolzan commented

2014-08-04 16:07:55 +02:00

Ok, thanks.

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Prefetch frames does not seem to take effect on playback #41165