Rocket Transcodes and speed-influencing factors

[Alexander Alexandrov]

trying to get a better understanding on things that influence the transcodes done with RedRocket and to what level.

i'm on a 8core mac 08 with rocket card in 8x slot.
as i understand it, the following items will influence my transcode speed:

1. position of the rocket card (8x slot is best if 16x is used for graphics card)
is putting rocket into a 16x and graphics into 8x a bad idea? will it make much difference?

2. graphics card itself (does it have any significant influence on speed? perhaps depending on the codec transcoded to? if so how?)

3. HDDs
does it make material difference if:
- i transcode to and from external drives connected via esata or fw800 (sure the speeds of data transfer differ but are the transcoding speeds beating the data transfer speeds here?)
- transcoding with reading from one drive and writing to another or doing both on the same? again, here are the transcoding speeds beating the drive read/write speed factors, and how significantly?
- RAID0 for speed, again, here are the transcoding speeds beating the RAID0 read/write speed factors, and how significantly?

4. number of cores. (but that's solid until you get a new computer and codec dependent too.

5. codec, resolutions, de-squeezing during transcode

if someone can shine a light on significance of each factor (or any other factors if i missed some) vs transcode speeds.

thank u

edit:
and on slightly different, but relevant topic, how much difference RAID0s, gpu power, additional cards (like kona, BM) make for editing, color, etc. speeds aside from red rocket? for example is hdd speed a number 1 limiting factor in here?or how would you sort them in order of significance.
thanks

 

[Dustin Cross]

I did some tests with my Graphics card (ATI 3870) and performance was no different in x16 or x8. I tried Color, Motion, and AE and all were the same x8 and x16.

Has anyone else actually tested GPU speed in x8 vs x16? I did because reading test of dual x16 vs dual x8 cards showed almost no performance gain.

So what is working best for me is:

x8 - ATI 3870
x8 - Red Rocket
x4 - Black Magic HD Extreme
x4 - Rocket Raid 2322

I don't know of any software that uses Red Rocket and GPU. Maybe Scratch, but I don't have that. So GPU isn't a big factor with Rocket right now.

Position of the Rocket Card is said to make a difference, but I have not tested performance in x4 vs x8 to verify, but enough people have problems if the card is not in x8.

The faster the drives the better. Going from one drive to another is good. Fast Raid is best.

Faster drives speed things up! Anything that reads and writes data.

Faster GPU speeds things up that use GPU! When I upgraded to 3870 Color changed drastically for the better.

BM & Kona don't speed up anything. Just allow I/O. Matrox speeds up h264 rendering.



Dusty

 

[Alexander Alexandrov]

thanks Dusty.
about the fast drives (raids, the way they are connected, written/read to/from)
are these factors even reached to make a difference when rendering via rocket or render itself is slower for drive factors to make a difference??

 

[Rich Schaefer]

Great thread Guys! Please keep the feedback coming.

How much dose RAM matter for speed?

Maybe a silly thought, but I would love to run 2 rocket cards for twice the speed. (Opening 2 versions of RCX one for each card)

Best,
Rich

 

[Jeff Kilgroe]

2 Rockets would be kinda nice for some things -- SCRATCH currently supports dual Rockets for stereoscopic stuff. But the bottleneck right now isn't the Rocket, it's first and foremost the storage in your system. If your storage is fast enough to handle what you are trying to do, the next bottleneck you will run into is the codecs or encoders being used for your transcodes. For example, Apple's QT encoder does not scale beyond a single CPU at this point and it's near impossible to get close to real-time transcodes from RED 4K to 2K or 4K QT files, no matter how powerful your system is.

There seems to be potential for future support of more than one Rocket for Redcine-X -- in the log files it reports the number of Rocket cards installed.

RAM only matters as much as having enough for the 32bit application space for Redcine-X. Yep, it's a 32bit application, so it technically can use around 3.5GB out of a 4GB heap, but individual processes are limited to 2GB within the 32bit environment, so it's hard to say. I haven't monitored specific RAM use on Redcine-X. As long as you have 4GB free that it can latch onto, you're good.

 

[Rich Schaefer]

Great info Jeff!

It makes me wonder how 2 or 3 solid state drives would do.

 

[Thomas Koch]

Hmm. I thought the whole point of red rocket was real-time transcodes, in my case to ProRes.

 

[Rob Gardner]

So what exactly does it take to achieve real time prores trans-codes? Anybody know? Is it achievable? We have an 8 core mac, Xserve raid, 8 gigs of memory and we seem to be doing about 1.5 to 1.
What is the best advice?

 

[Alexander Alexandrov]

i think it's hard to say exactly at this point as there are still loose ends.
i was using rocketcine before which was faster and now use redcineX with latest drivers and it is slower as it relates to just software.