A77/A65 HS Buffer Depth in 12MP mode?

Started Aug 30, 2011 | Discussions
MikeRan
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A77/A65 HS Buffer Depth in 12MP mode?
Aug 30, 2011

Anyone with hands on experience with A77 or A65 know if the shot buffer is deeper if the resolution is backed down from 24MP to 12MP?

I.e. I can only get 13 or 18 images (depending on JPG Mode) shooting at 12FPS at 24MP.

Can I get more than 13 or 18 shooting at 12FPS if I've set the resolution of the camera to the 12MP (or even the 6MP) mode? If so, how many?

Anyone with hands-on experience try it?

Also, I wonder why there has to be a buffer depth hit with RAW+JPEG when compared to RAW. Why can't these guys write the firmware to tag the RAW images that need to be converted and convert them to JPG during "idle" time? (Could cause problems when the card is ALMOST full, as there may be RAW images taken which there is no room to convert.) but this sounds doable.

-Mike

MikeRan
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to MikeRan, Sep 1, 2011

Noone???

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rinkos
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to MikeRan, Sep 1, 2011

MikeRan wrote:

Anyone with hands on experience with A77 or A65 know if the shot buffer is deeper if the resolution is backed down from 24MP to 12MP?

I.e. I can only get 13 or 18 images (depending on JPG Mode) shooting at 12FPS at 24MP.

Can I get more than 13 or 18 shooting at 12FPS if I've set the resolution of the camera to the 12MP (or even the 6MP) mode? If so, how many?

Anyone with hands-on experience try it?

Also, I wonder why there has to be a buffer depth hit with RAW+JPEG when compared to RAW. Why can't these guys write the firmware to tag the RAW images that need to be converted and convert them to JPG during "idle" time? (Could cause problems when the card is ALMOST full, as there may be RAW images taken which there is no room to convert.) but this sounds doable.

-Mike

hey mike..i can tell u what i tried to do with my A580 ..if u put down res by half u get a lot of increase in depth ..for me about 30 more shots ..compare to the 40 i had with 16mp sensor...

the main issue i think for buffer depth for the A77 is their huge file size..look at the latest version 1.02V ( they claim its the production version )

the jpeg file size is 16-18mp ..thats thrice my A580 jpeg files...i have no idea why.
maybe its also the new Extra fine compared to A580's standard and fine settings.

i bet then when u pick a logical settings u will get a much higher buffer depth.

oh by the way there is a link about the new SD cards comming up soon with speeds up to 12X the current ones...that would improve buffer depth by a whole lot.

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MikeRan
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to rinkos, Sep 1, 2011

Gotcha. I wonder on the A77, given it's 24MP and 12FPS, whether the limitation is really card writing, or data processing in the camera. If I assume 12-bits per pixel come off the sensor * 24MP = 36MB raw data per frame, * 12 frames, this translates to 432 megabytes of data to process per second. An impressive feat... But makes me wonder whether the "buffer" is on the input to the processor (i.e. buffering raw data) or on the output (i.e. buffering processed JPG's or RAW files.)

I suspect it's the former. If that's the case, I don't think the buffer depth is going to change that much if you drop the MP's from 24 to 12.

I hope I'm wrong...

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HopeSpringsEternal
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to MikeRan, Sep 1, 2011

The limitation is that in order for the image processor (processors in case of A900) to handle the incoming image data at 12fps, it has to be able to operate in parallel and needs somewhere fast to write data to. That fast destination is the on-board RAM buffer. The RAM buffer is then cleared in parallel to the flash media (Memory stick/SD). The throughput of the flash media in no way can compare to that of the on board RAM memory. As you calculated, no SD card can push 400+ MB of data per second. So, if you're shooting 12fps RAW images the on-board buffer is really what controls how much time you can shoot at full rate.

In the case of the A77, the buffer is too small given the sustained write performance of most SD and MS cards, the ability to only write to 1 flash device and the huge size of files being recorded.

So the A77 can shoot at 12fps but only for less than 1 second if you're shooting RAW or RAW+JPG. That is too short a period of time to be effective for capturing most action scenarios. Once that 1 second elapses, the camera really slows down and you can forget about capturing any action shots until the buffer clears which may take up to 30 seconds or more. This 12fps advertised shooting rate actually has the unfortunate side effect of misleading photographers into gunning the camera too early and then missing the desired shots when the camera's shooting rate plummets, less than a second later.

Sony should have installed at least twice the on board memory (at least on the a77, perhaps up to 4GB of RAM) and put in support for simultaneous writing to two flash devices at once (alternating,JPG to one flash, RAW to the other,etc..). This would have made the 12fps shooting feature more useful by increasing shooting time to four seconds at max file size (JPG+RAW).

Perhaps this will be rectified on a future and higher end model.

MikeRan wrote:

Gotcha. I wonder on the A77, given it's 24MP and 12FPS, whether the limitation is really card writing, or data processing in the camera. If I assume 12-bits per pixel come off the sensor * 24MP = 36MB raw data per frame, * 12 frames, this translates to 432 megabytes of data to process per second. An impressive feat... But makes me wonder whether the "buffer" is on the input to the processor (i.e. buffering raw data) or on the output (i.e. buffering processed JPG's or RAW files.)

I suspect it's the former. If that's the case, I don't think the buffer depth is going to change that much if you drop the MP's from 24 to 12.

I hope I'm wrong...

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spazz
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to HopeSpringsEternal, Sep 2, 2011

I'll be able to play with the a77 tonight so I'll let you know how many frames it can take with lower resolution. If you have any other questions or queries let me know so I can ask Sony tonight.
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spazz
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to spazz, Sep 2, 2011

After playing with the a77 tonight, I can let you know that even with the megapixels lowered at 12mp and 6mp, the buffer still fills up at the same rate. Hope that clears things up for you.
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Kilrah
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to spazz, Sep 2, 2011
 Kilrah's gear list:Kilrah's gear list
Sony Alpha DSLR-A300 Sony Alpha DSLR-A580 Sony SLT-A77 Sony DT 18-55mm F3.5-5.6 SAM Sony DT 18-70mm F3.5-5.6 +6 more
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spazz
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to Kilrah, Sep 2, 2011

v1.02 They said this is still not the final firmware version so bare in mind, it might get better but I'm not sure if this is something that can be fixed with firmware or better hardware. Either way, we'll see soon.
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sybersitizen
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to spazz, Sep 2, 2011

spazz wrote:

After playing with the a77 tonight, I can let you know that even with the megapixels lowered at 12mp and 6mp, the buffer still fills up at the same rate. Hope that clears things up for you.

It doesn't clear things up for me. It only raises more questions because the total number of images captured by the buffer ought to increase significantly when switching from RAW to reduced resolution JPEGs. My A55 works this way, almost doubling the frame depth compared to RAW shooting, and just as important, it also dramatically reduces the buffer clearing time afterwards.

But Imaging Resource has also reported that unexpected behavior with the A77: no appreciable improvement when switching to JPEGs. I hope this is only the case with pre-production firmware and not some strange behavior that persists in the production cameras.

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Kilrah
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to sybersitizen, Sep 2, 2011

It wouldn't be surprising.

The usual way is that a camera shoots, processes, then buffers the result and writes to the card when it can.

Maybe to achieve 12fps they're forced to shoot, buffer the raw data, and wait until the burst is finished to process and write.
It would explain the same buffer depth for RAW and Superfine JPEG.

The higher number of JPEGs in Fine and Standard could be the result of some chroma subsampling taking place, and as the camera knows the JPEG encoder will throw some info out it simply throws it out right after sensor readout and before buffering.

JPEGs should clear out significantly faster though, due to the smaller amount of data to write to the card (which is usually the bottleneck).

 Kilrah's gear list:Kilrah's gear list
Sony Alpha DSLR-A300 Sony Alpha DSLR-A580 Sony SLT-A77 Sony DT 18-55mm F3.5-5.6 SAM Sony DT 18-70mm F3.5-5.6 +6 more
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MikeRan
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to spazz, Sep 2, 2011

Thanks for reporting back. I guess I'm disappointed, but not too surprised, based on my thoughts above.

I guess we can still hope that the buffer is deeper at 8FPS... (You didn't happen to run that test, did you? Sorry I didn't ask before.)

-Mike

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spazz
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to MikeRan, Sep 3, 2011

MikeRan wrote:

Thanks for reporting back. I guess I'm disappointed, but not too surprised, based on my thoughts above.

I guess we can still hope that the buffer is deeper at 8FPS... (You didn't happen to run that test, did you? Sorry I didn't ask before.)

It would've been the next logical test but I didn't test that, sorry. I certainly think it would be able to take more frames if its only 8fps but no way to be sure until final production cameras come out.
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MikeRan
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Re: A77/A65 HS Buffer Depth in 12MP mode?
In reply to spazz, Sep 3, 2011

Gotcha. Thanks very much.

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