Author Topic: Faster save by RAM "dump" instead of creating image/movie files?  (Read 133 times)

Rainer

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Hello all,
I don't have a Chronos (yet) but another HighSpeed Cam from PCO. The limiting factor when shooting multiple scenes is the time it takes to save the buffer via USB to disk.
On the forum I read a lot about Chronos saving speeds with different file formats and storage media and I feel that this would affect me heavily when I get a Chronos.

Would the following suggestion increase the saving speed (mainly a questions for the Krontech devs):
Instead of converting the RAW image data from the RAM into h264, DNG, ... do the following: dump the data from the RAM exactly as it is in the RAM (no conversion to any file format).
One would end up with a huge binary dump on the storage medium.
Later - on the computer - one could convert this binary dump into h264, DNG, ...
I have the feeling that the conversion from RAW to an image format is a time consuming step for the FPGA in the Chronos. If this step is "outsourced" to a computer, would it make continuous shooting faster?
It's just an idea, but I would use it right away with every high speed cam I ever used.
Thanks for reading my suggestion, I am really interested if this would be feasible.
Rainer

Nikon1

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Re: Faster save by RAM "dump" instead of creating image/movie files?
« Reply #1 on: October 10, 2021, 03:04:21 PM »
There is an option like this on the Chronos, you can save in RAW, which will essentially dump the Entire RAM Data into one massive File, which needs to be processed by the PC later.

Rainer

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Re: Faster save by RAM "dump" instead of creating image/movie files?
« Reply #2 on: October 11, 2021, 01:17:57 AM »
Oh, I did not know that. Is it improving the saving speed?

Nikon1

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Re: Faster save by RAM "dump" instead of creating image/movie files?
« Reply #3 on: October 12, 2021, 01:08:06 PM »
For RAW its supposed to be Faster than all other Formats. Compressed H.264 Is however still fastest overall from what i know, just because of the way smaller Filesize to write to memory.
 .
 See Page 90 of the User Manual for a Comparison:
 https://www.krontech.ca/wp-content/uploads/2021/09/RE-PDEV-10009-Chronos-User-Manual-Full-Software-Version-0.7.0.pdf
 .
 Saving in RAW Format seems to not be too popular amongst the average user, just because H.264 is overall just a lot faster and Smaller file size, and CinemaDNG is a lot easier to work with and wont need to be converted later, and can be directly imported to most advanced Video Editing Software. Only heard a few people use it where they still want some kind of uncompressed Footage, and Save Speed is absolutely critical.
 I tried Saving in RAW, but stayed with CinemaDNG because it just saves me all the work of converting, which makes it overall still fastest uncompressed Format for me, if i factor in processing time after Shooting, even if it takes a little bit longer to save technically. If i need to move really fast, and i just try to get footage at all and not tickle out the Last bit of Quality, i would use H.264 Anyways, its like a order of magnitude faster.

Rainer

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Re: Faster save by RAM "dump" instead of creating image/movie files?
« Reply #4 on: October 12, 2021, 11:41:12 PM »
Thanks for this real-world experience and feedback, Nikon1

NiNeff

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Re: Faster save by RAM "dump" instead of creating image/movie files?
« Reply #5 on: October 13, 2021, 03:17:40 AM »
The processing overhead for creating DNG files or H.264 encoded MP4 files is relatively low compared to the other factors like drive&bus speed.
You won't see a significant speed improvement if you compare raw to DNG saving, but it is there. Mostly because only one large file needs to be created. (Which might lead to FAT32 problems if it gets too big)

The fastest saving is H.264 encoded MP4, but it goes along with quality reduction.

To get the highest speed you should use the eSATAp Port instead of USB and safe to a SSD.