Author Topic: 8 bit Raw recording to acomplish 50fps?  (Read 1488 times)

pc_bel

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8 bit Raw recording to acomplish 50fps?
« on: February 16, 2017, 10:04:33 AM »
Hello,
I'm really excited for the continuos developement of Magic Lantern, and especially the last 10-12 bit and crop mode features. I'm really grateful for this.
For me (and sure for more people) 1080p is all I need (mostly web destination works), but allways hopping for a 50fps solution for slowmo. Now, thanks to all developers we have two options to get 50fps: squeezed one and the newer 3x3 binning. Both have his pros and cons.

I guess if getting 8bit recording, datarate can go down enought to get 1080p50 raw. I know you loose the benefits of 10-12-14 bit for post, but to have 50p without sqeezing and pixel binning will be a 3rd option...(?)

Maybe I'm totally wrong and datarate is not the only problem. In this case feel free to delete this post if you want.

Thank you very much.

ItsMeLenny

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #1 on: February 16, 2017, 12:42:08 PM »
I don't think it would still be enough because it's uncompressed data.
If the RAW image could be compressed with jpeg or mp4 compressed then you'd be laughing. :P

Levas

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #2 on: February 16, 2017, 03:55:46 PM »
I'm not 100% sure, but as far as I know lower then 10 bit isn't possible.
The value that ML uses to tweak bit depth to 10, 12 and 14 bits, is set at zero for 10 bits.
Looks like this in source code:
#define MODE_14BIT 0x030
#define MODE_12BIT 0x010
#define MODE_10BIT 0x000

So, since there is no lower value below the 10 bit option I guess 8 bit is not possible.
 

dmilligan

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #3 on: February 16, 2017, 08:52:36 PM »
datarate is not the only problem
Bingo. In fact "datarate" is only a problem if you want continuous recording (recording short bursts would be possible regardless of bit depth used). However, it takes the sensor a finite amount of time to readout each row (this is the source of "rolling shutter"). The sensor itself is simply not fast enough to readout 1080 rows in less than 1/50th of a second (per row that's about 18 microseconds).

pc_bel

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #4 on: February 16, 2017, 09:14:46 PM »
@dmilligan
Ok, I understand that the problem is before any "data rate". So the sensor is not able to read so fast.  :-[

Sorry for start this...

Anyway, the actual 10-12-14 bit, crop mode, and now simultaneus H264 recording is amazing!!!!! Thank you for all of this!!!!

cmccullum

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #5 on: February 17, 2017, 02:09:22 AM »
Simultaneous h.264?? Meaning we are able to record raw and h264 simultaneously?? Where was this discussed, and how did I miss it?????

dmilligan

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cmccullum

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Re: 8 bit Raw recording to acomplish 50fps?
« Reply #7 on: February 18, 2017, 12:19:37 AM »
Wow awesome! Thanks