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Author Topic: Filling the buffer  (Read 2338 times)

Don Haines

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Filling the buffer
« on: February 07, 2013, 12:41:01 PM »
I decided to do a test to see how many frames it would take to fill the buffer of the camera in various recording modes.

Camera used 60D, 1000th of second shutter speed, manual focus, high shutter rate (5.9 frames per second)... The list is of how many shots it took before the buffer filled and the frame rate dropped.

RAW and Ljpeg (5184x3456) - 6 frames

Ljpeg (5184x3456) - 8 frames
Mjpeg (3456x2304) - 8 frames
S2jpeg (1920x1080) - 8 frames

RAW (5184x3456) - 14-15 frames
MRAW( 3888x2592) - 15 frames
SRAW(2592x1758) - 15-16 frames

Before the test, my assumption was that smaller files would mean more files dumped to the memory card before it stuttered, and that small jpegs should allow a much larger number than full sized RAW files. In fact, the opposite happened.

I interpet the results to mean that my assumption of writting the files to the flash drive being the bottleneck was wrong. It seems obvious that the internal memory becomes filled with RAW data waiting to be converted to Jpeg... the bottleneck is processing to Jpeg.... get rid of that process and the number of pictures before stuttering doubles. The next bottleneck is processing the raw files (including reading them off of the sensor), changing the output RAW size has almost no effect on the buffer, so once again, the flash card is not the bottleneck.

So the limitation is computing power.... not card speed. Anyone care to try this test on a different camera model?
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Filling the buffer
« on: February 07, 2013, 12:41:01 PM »

bseitz234

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Re: Filling the buffer
« Reply #1 on: February 07, 2013, 02:22:56 PM »
I decided to do a test to see how many frames it would take to fill the buffer of the camera in various recording modes.

Camera used 60D, 1000th of second shutter speed, manual focus, high shutter rate (5.9 frames per second)... The list is of how many shots it took before the buffer filled and the frame rate dropped.

RAW and Ljpeg (5184x3456) - 6 frames

Ljpeg (5184x3456) - 8 frames
Mjpeg (3456x2304) - 8 frames
S2jpeg (1920x1080) - 8 frames

RAW (5184x3456) - 14-15 frames
MRAW( 3888x2592) - 15 frames
SRAW(2592x1758) - 15-16 frames

Before the test, my assumption was that smaller files would mean more files dumped to the memory card before it stuttered, and that small jpegs should allow a much larger number than full sized RAW files. In fact, the opposite happened.

I interpet the results to mean that my assumption of writting the files to the flash drive being the bottleneck was wrong. It seems obvious that the internal memory becomes filled with RAW data waiting to be converted to Jpeg... the bottleneck is processing to Jpeg.... get rid of that process and the number of pictures before stuttering doubles. The next bottleneck is processing the raw files (including reading them off of the sensor), changing the output RAW size has almost no effect on the buffer, so once again, the flash card is not the bottleneck.

So the limitation is computing power.... not card speed. Anyone care to try this test on a different camera model?
7d, 8fps, ISO 100, 1/1000, nifty-fifty @ f/1.8:

RAW 28frames
JPEG (L): Until I didn't want to have to delete any more. Which was 100 frames. and it was done writing as soon as I was done (no lingering red light for "card busy")

Out of curiosity, what card did you use? Maybe that does matter... mine's a SanDisk Extreme (60 MB/s) 16GB...
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Swphoto

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Re: Filling the buffer
« Reply #2 on: February 07, 2013, 03:10:15 PM »
Don, what card were you using? I did a similar test with my 60D and took well over 100 frames in JPG (large) without filling the buffer. Same results with a 7D and 5D2/3 (all CF, no SD used on the 5D3).

Regarding RAW, when I went from a Patriot Class 6 SD card to a SanDisk Extreme I saw a major jump in how quickly it recovered from a RAW burst (flushed the buffer to the card). I don't remember exact times, but it was a significant change - probably 12 seconds before the red light went off vs 20.

FYI, you can find detailed performance info here: http://www.imaging-resource.com/PRODS/E60D/E60DA6.HTM

Looks like he used an older/slower card for those numbers - mine was significantly faster across the board with the Extreme 45MB/s card.
« Last Edit: February 07, 2013, 03:16:07 PM by Swphoto »

justawriter

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Re: Filling the buffer
« Reply #3 on: February 07, 2013, 04:43:29 PM »
The High ISO Noise Reduction (which is actually active at all ISO settings) on the Canon cameras will drop the camera's ability to buffer photos drastically. I shoot some basketball games in some poorly lit high school gyms and rather than limit myself to single shots with a flash I pump up the ISO to 4000 or 5000 most nights. I shoot with Noise Reduction set to high and I can only shoot four photos in a burst with my 7d.

R1-7D

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Re: Filling the buffer
« Reply #4 on: February 07, 2013, 04:51:23 PM »
The High ISO Noise Reduction (which is actually active at all ISO settings) on the Canon cameras will drop the camera's ability to buffer photos drastically. I shoot some basketball games in some poorly lit high school gyms and rather than limit myself to single shots with a flash I pump up the ISO to 4000 or 5000 most nights. I shoot with Noise Reduction set to high and I can only shoot four photos in a burst with my 7d.

I thought in-camera noise reduction while shooting in RAW didn't do anything...?
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bseitz234

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Re: Filling the buffer
« Reply #5 on: February 07, 2013, 07:53:36 PM »
The High ISO Noise Reduction (which is actually active at all ISO settings) on the Canon cameras will drop the camera's ability to buffer photos drastically. I shoot some basketball games in some poorly lit high school gyms and rather than limit myself to single shots with a flash I pump up the ISO to 4000 or 5000 most nights. I shoot with Noise Reduction set to high and I can only shoot four photos in a burst with my 7d.

I thought in-camera noise reduction while shooting in RAW didn't do anything...?

It shouldn't, that kind of defeats the purpose of RAW...
7D x2
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580ex II - 2x 430ex II

jdramirez

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Re: Filling the buffer
« Reply #6 on: February 07, 2013, 09:18:58 PM »
I had a sandisk class 10 and I took photos with large jpgs and I was able to take 60 photos and it wasn't even close to slowing down. 

When I shoot in raw, I get about 7 ish before I stop... but I try not to shoot 20 or 30 at a time.
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Re: Filling the buffer
« Reply #6 on: February 07, 2013, 09:18:58 PM »

Don Haines

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Re: Filling the buffer
« Reply #7 on: February 07, 2013, 10:05:28 PM »
The High ISO Noise Reduction (which is actually active at all ISO settings) on the Canon cameras will drop the camera's ability to buffer photos drastically. I shoot some basketball games in some poorly lit high school gyms and rather than limit myself to single shots with a flash I pump up the ISO to 4000 or 5000 most nights. I shoot with Noise Reduction set to high and I can only shoot four photos in a burst with my 7d.

You were bang on. I set High ISO Noise Reduction to disabled and was unable to fill the buffer shooting continuously.... I gave up after 150 shots.

My earlier observations showed that it had to be a computing power problem. If it was a card wrtite speed problem changing the raw file settings would have sped up the rate, but it had no effect... Likewise, if it was a write speed problem, why would 8 tiny jpegs fill the buffer quicker than 16 large raws?

Thanks for the tip.... I had assumed that high ISO reduction would only affect high ISO shots, not everything.... and I was wrong.
« Last Edit: February 07, 2013, 10:07:36 PM by Don Haines »
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Pagesphotography

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Re: Filling the buffer
« Reply #8 on: February 07, 2013, 10:13:39 PM »
Also, when formatting the memory card, be sure to us the "low level format" option

justawriter

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Re: Filling the buffer
« Reply #9 on: February 08, 2013, 11:36:50 AM »
Here is a link to an article what NR does and how it affects shooting.
http://www.learn.usa.canon.com/resources/articles/2011/high_iso_noise_reduction_article.shtml

Don Haines

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Re: Filling the buffer
« Reply #10 on: February 08, 2013, 04:24:10 PM »
Here is a link to an article what NR does and how it affects shooting.
http://www.learn.usa.canon.com/resources/articles/2011/high_iso_noise_reduction_article.shtml

This is why I like this forum.... I notice something strange... ask a question, and the answer(s) are given. Thanks all!
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Re: Filling the buffer
« Reply #10 on: February 08, 2013, 04:24:10 PM »