Magic Lantern 0.1.4 Is Out- Adjustable Gain and Zebras are now in! at DVinfo.net

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Old June 23rd, 2009, 10:59 PM   #1
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Magic Lantern 0.1.4 Is Out- Adjustable Gain and Zebras are now in!

Hang on to your hats, the Wizard is brewing some more home brew!

Title speaks for itself. I have loaded to my Canon 5D Mark II, and after booting, go to the Picture Style button. There in small print on left center is area. You go up or down and adjust with the toggle.

I will be testing tonight, but this means a lot more to us, depending on what you are using to get sound to your camera....

Go Here :

Magic Lantern Firmware Wiki
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Old June 23rd, 2009, 11:26 PM   #2
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Zebra setting appear to be as follow:

I am guessing here, but Zebra setting appear to be selectable as follow:

f000------------> 100%
b000------------> 90%
7000------------> 80 %
3000-------------> 70%
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Last edited by Chris Barcellos; June 24th, 2009 at 12:55 AM.
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Old June 23rd, 2009, 11:39 PM   #3
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Digital Gain

Adjustable to 0,6,,12,18,24,30,36
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Old June 24th, 2009, 12:47 AM   #4
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Analog gain is a bit out of order, per Hudson:

MGAIN register values don't quite go in order, sorry:
0 == +0 dB
1 == +20 dB
2 == +26 dB
3 == +32 dB
4 == +10 dB
5 == +17 dB
6 == +23 dB
7 == +29 dB
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Old June 24th, 2009, 02:10 AM   #5
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Here's a quick guide to analog and digital gain.

The best performance will come at A:0, D:0, assuming you have a mic/preamp that has enough signal that is clean.

I found that you can increase the analog gain to +10 without much extra noise. The levels at 17 and above start to junk things up.

With digital, every time you increase the gain by 6dB, you are throwing away one bit. You want as many bits as possible if your signal is clean. If it's dirty, you can throw away bits with abandon.

So, my progression would be something like this...

* A:0, D:0 // Cleanest signal possible - but you need a strong signal input
* A:0, D:6 // I'll probably skip over this
* A:10, D:0 // Still very clean
* A:10, D:6
* A:10, D:12 // The default in Magic Lantern 0.1.3
* A:17, D:12
* A:20, D:12
* A:20, D:18 // This is about as far as I'd push it. It's already pretty noisy here. Might as well add gain in post...
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Old June 24th, 2009, 02:26 AM   #6
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Jon:

I was hoping you would come along with a primer. Thanks a lot for that.
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Old June 24th, 2009, 03:38 AM   #7
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Chris, is that supposed to be a download link for the latest version? If so it's still showing the first release.
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Old June 24th, 2009, 04:23 AM   #8
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Although I am a sound engineer...I am confused by the 'analog/digital' option you refer to.
The 5D2 has an stereo minijack input ...that's obviously an analogue input.
Where is the selection to allow a digital input?

I'm currently recording sep sound on an Edirol R-44, a far better recorder than the H4n and not really much bigger. It works well but I am interested by Tramm's mods to the audio, as even if I just sent a monitor signal to the camera to use the level meter's I would find a use for the Magic Lantern..plus the 'zebra's' would be great of course.

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Old June 24th, 2009, 05:48 AM   #9
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As I understand it, the input is always analog, but you can add analog gain (electronic, like turning the gain knob on a preamp) or digital gain (zeros and ones, like using your DAW to increase gain).
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Old June 24th, 2009, 07:35 AM   #10
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Quote:
Originally Posted by David W. Taylor View Post
Although I am a sound engineer...I am confused by the 'analog/digital' option you refer to.
The 5D2 has an stereo minijack input ...that's obviously an analogue input.
Where is the selection to allow a digital input?
The AK4646 that is used in the 5D has an analog pre-amp, a ADC, a digital filter stage and then a digital gain stage. The ALC works by adjusting the digital gain; the Magic Lantern firmware turns off the ALC and allows a fixed gain to be set in the digital stage. The digital gain stage doesn't add any new data, so if you increase the gain it just zero-pads the LSB in the samples. You can do that in post just as well, and keeping the digital gain low on the camera ensures that there is plenty of headroom for hot mics.

Jon's tests found that the 5D's preamp is pretty noisy if turned past +10 dB of gain and that it was much better to use an external preamp like the CX231. Canon defaults to +20 or +29 dB which is one of the reasons the noise levels are so high with the stock firmware.
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Old June 24th, 2009, 07:39 AM   #11
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Quote:
Originally Posted by Chris Barcellos View Post
I am guessing here, but Zebra setting appear to be selectable as follow:

f000------------> 100%
b000------------> 90%
7000------------> 80 %
3000-------------> 70%
Sure, that sounds reasonable. Your guess is as good as mine.

The img_vram buffer that is being analyzed for the zebras is a planar YUV with 16-bit luminance samples. I do not know the transfer function that they are using for the conversion, so it is difficult to come up with IRE equivalents. The zebra threshold is solely based on the Y values.

If anyone has a better idea, please let me know!
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Old June 24th, 2009, 08:06 AM   #12
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Quote:
Originally Posted by Robert Esmonde View Post
Chris, is that supposed to be a download link for the latest version? If so it's still showing the first release.
The link is new firmware 0.1.4 for replace the old one 0.1.3
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Old June 24th, 2009, 08:12 AM   #13
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Originally Posted by Cuong Dinh View Post
The link is new firmware 0.1.4 for replace the old one 0.1.3
Yes, but the point I was making is that it leads to the old download option and I can't see any link on the page for firmware 0.1.4.
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Old June 24th, 2009, 09:14 AM   #14
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Originally Posted by Robert Esmonde View Post
Yes, but the point I was making is that it leads to the old download option and I can't see any link on the page for firmware 0.1.4.
The wikia site seems to do some pretty aggressive caching between servers for load balancing. Sometimes it takes a while for edits to propagate, especially image thumbnails.

I just tried explicitly purging the cache on the download page. Does the 0.1.4 link show up for you yet?
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Old June 24th, 2009, 09:34 AM   #15
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Thanks Tramm. Just tried again and the 'Downloads' link brings me to this page:

Download firmware - Magic Lantern Firmware Wiki

The download file there is still 0.1.3.zip

Am I missing something, since I'm the only person who seems to have this problem?

Quote:
Originally Posted by Tramm Hudson View Post
The wikia site seems to do some pretty aggressive caching between servers for load balancing. Sometimes it takes a while for edits to propagate, especially image thumbnails.

I just tried explicitly purging the cache on the download page. Does the 0.1.4 link show up for you yet?
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