Hi

I'm having slow playback issue when tring to play in Color Corection mode.

I have 128GB of Ram.

What is the best Cache setting in Media Composer for best real time playback?

Thanks

Yair

Its not easy to answer that as so many factors come into play.

If you have a massive cache MC will be busy loading that cache up and during that time you may experience reduced performance. When the cache is full you gain a longer window of playback before the cache need refreshing.

However as colour correction mode will by its nature be applying realtime corrections you are having to process the cache contents to reflect the CC changes so this impacts performance.

This all sits ontop of the OS cache that is already transfering drive media to RAM

So I'd test performance over a reasonable editing timeframe (a few hours at least) with a range of Media Cache sizes.

Start small, say a few GB then jump up in steps of a few GB at a time.

Hi Pat,

In the Media Cache window there are 2 tabs that I think are relevant to my case.

The Video Memory, inside there is the Video Memory slider(I set it to 40GB)

and the 2 checkbox for Playback and FX Frame Cache, are both on.

The other tab is the File Cache which I set to 60GB.

What would you recomand for me as for those 2 tabs?

Thanks for your replay!

Yair

It makes no sense that one gets smoother playback with blackmagic io than full screen playback.

cls105:

It makes no sense that one gets smoother playback with blackmagic io than full screen playback.

Yes it does. With external IO MC passes the data to the IO and hardware takes care of shipping out to the display. In FS playback the cpuu and gpahics card are working hard displaying the image. 

Ok.  Point is, today's gpus can handle full screen playback but do it poorly in media composer.

video games are rendering 3d at high resolutions at 60 FPS.

media composer should at least improve it.

I have the same question. Did you find an answer, Yair?

That's true but one of theong standing strengths of Media Composer is it will run on a range of hardware without the need for GPU support. 

This low editors to use MC on lower spec machines. 

If GPU performance was demanded a whole bunch of editors would have to upgrade systems. 

I'm no programmer so I have no idea if it's possible to build a playback engine that can adapt to GPU or CPU dynamically but I have worked with other NLEs that claimed they could with frustrating results. 

YOP:

Hi Pat,

In the Media Cache window there are 2 tabs that I think are relevant to my case.

The Video Memory, inside there is the Video Memory slider(I set it to 40GB)

and the 2 checkbox for Playback and FX Frame Cache, are both on.

The other tab is the File Cache which I set to 60GB.

What would you recomand for me as for those 2 tabs?

Thanks for your replay!

Yair

I would think that is far too much even with 128GB ram. Try backing off those sliders to say 10GB or less.

Media Composer does balance load between gpu and cpu for real time fx and scaling, but how much and whether that works for FS software playback is unknown. In any case the FS is really only useful for an offline use. Hardware io decompresses the timeline to SDI/HDMI, without any pc display contamination. It also makes sense that hardware io would be smoother when you consider that MC has to 'translate' 30p, 50i, 24p etc. to 60Hz computer displays on the fly.

Happy new year Pat.

Pat Horridge:

one of theong standing strengths of Media Composer is it will run on a range of hardware without the need for GPU support.

Not sure if the Resolve development team and user base would agree on that.

Pat Horridge:

If GPU performance was demanded a whole bunch of editors would have to upgrade systems.

Is Avid really holding back on GPU performance so the ones that use older hardware (from ebay) or the budget pc build users can stay on board? I must be misinterpreting you.

Pat Horridge:

I'm no programmer so I have no idea if it's possible to build a playback engine that can adapt to GPU or CPU dynamically but I have worked with other NLEs that claimed they could with frustrating results. 

I'm with you that very few would benefit from destabilizing MC in exchange for trying to achieve more performance. But with that attitude we could have stayed 32 bit and kept quicktime for decades to come. Maybe even revert the move to tapeless... and those bad camera and monitor manufacturers that pushed for HD, 2K, 4K 8K,

All irony aside, if putting in manual media cache adjustment options in MC results in answering OP's question with:

Pat Horridge:

Its not easy to answer that as so many factors come into play.

So I'd test performance over a reasonable editing timeframe (a few hours at least) with a range of Media Cache sizes.

Start small, say a few GB then jump up in steps of a few GB at a time.

Isn't it obvious that crucial information is missing when you have to reside to: 'You test all combinations out yourself'?

I can only see it as I find it. I don't work for Avid or am on the development team.

I know about the systems my clients use and many many of them are on very old systems.

None run Resolve as offline suites. all run hundreds of Avid offline suites on low spec systems.

Granted Resolve leaves Avid standing in terms of playback performance across a range of codecs but Resolve can't do lots of what my clients need so its a mute point.

As for my suggestion re testing. Its just that a suggestion. Its what I'd do. In fact its what I do even if Avid did have clearer advice on it.

Pat Horridge:

Granted Resolve leaves Avid standing in terms of playback performance across a range of codecs but Resolve can't do lots of what my clients need so its a mute point.

As a heavy user of Resolve too I can almost say categorically this isn't the case. MC will play most all things realtime, with reasonable specs, whereas Resolve has still an unecassarily complex proxy/cache setup and too much reliance on gpu to make offline editing practical competition in an Avid world.

Hi Pat and everyone else on this thread!

Here's the best advice I found from Avid: 

https://avid.secure.force.com/pkb/articles/en_US/How_To/Correct-interactive-frame-cache-or-Media-Cache-settings-in-Media-Composer#

Pretty much what you said with more details. As someone said, even for 128GB RAM, the settings described by the original poster seem high.

Joyce

Indeed my take away is take car in allocating too much RAM. Even if you have loads to spare.

The relationship between the OS, drive and Media Composer buffers can just result in lots of moving data from one cache to another.

Experimenting is the only way to factor in all the conditions affecting your systems and its setup. No two systems will be the same.

Hi Hartfilms,

This article is a part of another also by Chris Bove in cooperation with Avid: http://www.avidblogs.com/how-avid-media-composer-uses-a-computer/

Part of information is presented when used on Mac and that should not make much of a difference regarding the media cache settings. On Mac it does however leave the GPU out of the equation. As most of us know that mac os & nVidia are not 'best of friends', especially considering recent developments in 2020, this makes sense. (What the further impact will be on the graphics and video editing industry of the Apple M1 chip and GPU compatibility... time will tell)

On the PC side of things there is however a (supported) GPU with more and more memory for which Avid stated the following in this article:

- 1. GPU is front loaded/preferred by composer when playing a timeline.

- 2. SOME colour adapters are processing intensive and thus run better with a more powerful GPU

- 3. SOME effects are processed by the CPU, more recent have been engineered using GPU.

And this makes the video cache setting so complicated because you now have 2 caches of which you can control only 1. How do you determine a bottleneck between a CPU or GPU and how does the video cache help if the GPU doesn't have enough memory or a powerful GPU helps if not enough memory is available? 

Is OP's collor correction mode performance a CPU + cache or GPU issue? Two caches make things complicated but the use of the word SOME and not having indicators in your timeline or during other process if something is utilizing GPU and being bottlenecked... sigh.

I remain in my position that still having to reverse engineer this is tragic regardless if the underlying motivations are backwards compatibility, Mac OS <-> Windows (development) compatibility or being able to run on 'low' performance hardware.

We are going forward again faced with Apple and Microsoft running on different processor platforms where only 1 out 3 (M1, AMD, Intel) is currently supported. Will this split make the above even more complicated? Who knows? All I have been able to conclude is that supporting MacOS can forever be used as an excuse for lack of GPU integration. But not as an excuse that it is 'ok' for the users to figure it out themselves.