Trying to understand DCP workflow

[Aaron Boxer]

Hello!

I am curious about how users typically get their uncompressed data into the PC to get encoded.

A few options I can see are:

1) Compact Flash card ( with card reader on PC)
2) external SSD hard drive (plugged into eSATA port ? )

I assume that the data would be stored as uncompressed TIFF images.

The reason I ask is: I am continuing to progress with my accelerated JPEG 2000 codec.  Currently, I can compress
a 2048x1024 RGB 12 bit TIFF in 45 ms. This includes reading the file from SSD, and moving it to the card.
I have been careful to clear the Windows file cache before running my tests, to ensure that they reflect real-world
workflow, where files are only read once before encoding, and are not cached.

Once files are read from disk, the encoding is quite rapid. So, the frame rate for my encoder is dominated by reading from disk.
In fact, once it is finished, I think I will be able to compress images as fast as I can read them.

According to my calculations, any DCP creation software will be limited by disk reads: they will not be able to compress 2K images faster
than about 20 frames per second.  For 4K, this upper limit will be 5 FPS.  Does this make sense? Or am I missing something.

Thanks very much,
Aaron






 

[SL film]

http://www.knuterikevensen.com/?p=437

[Lars Goldschlager]

Greetings Aaron, I've been trying to follow your progress reports on OpenJPEG and awaiting something I can try out someday.

Normally in our lab we work with 16 Bit TIFFs as source 85% of the time, eventually we do work with 12 Bit Lineal DPX.

For the compression stage, and for the mxf building stages, we drop the workload on a raid 0 SSD array over sata 3 (internal), to increase performance as much as possible, yet we're currently working with 8 cores (cpu), so the disk speed seems to balance well with the encoding process for now.

In the future we're looking at making an investment on a hardware raid over thunderbolt 2, probably SSD, to increase performance as much as possible IO wise, but this is a middle/far future idea and not something that'll be implemented on the short run.

Coordialmente,

Lars Goldschlager

CTO, Director

DRG Cine Digital
+58-416-904-3546

http://www.knuterikevensen.com/?p=437

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