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Author Topic: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?  (Read 6725 times)

JasonATL

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #15 on: December 03, 2012, 07:54:59 AM »
You can see the Magic Lantern HDMI results here: https://vimeo.com/52822486

Some have said above that ML's implementation is lacking. That seems to misplace the blame on ML. They are working with what they have in terms of the current limitations. The primary limitations are: 1) The resolution that the Canon firmware makes available to HDMI (1620x1080); 2) The fact that the HDMI out is 1080i.

Because of 1, the same frame that is internally recorded must be cropped (zoomed) from the HDMI output, so the resulting resolution is 1620x911 (and does not even appear to perfectly resolve that resolution, just as the native 5D3 footage does not resolve the full 1920x1080 resolution).

The interlacing is a real pain and limitation. While there could be a limitation in the Hyperdeck Shuttle that I used in recording the interlaced signal, I simply could not reliably reconstruct the 24p signal. I could reconstruct it with a lot of effort, but it was a bit soft. Even the 30p signal was a bit soft after deinterlacing.

My own testing using a resolution chart shows that the HDMI out from ML does seem to resolve about the same resolution as the internal recording, albeit with pillar bars (since it is only 1620x1080). Oddly, though, the shot must be framed differently, since you must zoom in. Thus, with a very good deinterlacer, this might be useful for greenscreen work (assuming you don't need the full 16x9 frame).

In short, while the ML clean HDMI out might be useful for some purposes, it doesn't work for me right now in its current implementation to yield any significant benefits. There is a chance that ML can improve their HDMI out. However, I suspect that the 1080i HDMI output is something that they simply cannot overcome.

I don't think the ML implementation gives us any indication of what Canon's firmware will be. If Canon were going to do what ML did, they could have released clean HDMI already. This gives me hope that they will 1) give us at least as good a resolution as currently is recorded internally; and 2) provide a true 24p signal or at least have the 1080i embed the 24p information so that it is easily and cleanly recoverable. If they do these things, then the externally recorded material should show significant benefits, even if it is 8 bits. The benefits will be in less compression artifacts on highly detailed and dynamic (in motion) material from the higher available bit rates and less color compression from 4:2:2 vs. 4:2:0.

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #15 on: December 03, 2012, 07:54:59 AM »

HurtinMinorKey

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #16 on: December 03, 2012, 09:16:36 AM »
HDMI is a data transfer protocol standard, just like TCP/IP or USB. And it's a dumb consumer-level standard...its professional sibling is called SDI. And on the C300 you get both options, and Atomos makes a higher end Ninja they call the Samurai that just does SDI instead of HDMI. HDMI was for HDTV, which for legacy reasons uses 1080i60, sending half the lines 30 times per second, alternating with the other half (all interlaced together) also 30 times per second. There is nothing a camera or anything else can do to alter the protocol...that's how the machines have all agreed to talk, and because it's so dumb a standard, you can expect any HDMI monitor or whatever to understand it.

HDMI is capable of delivering progressive frame formats. I you use one with a blue ray player, that's what it's doing.  In fact, if I don't use HDMI and instead use component cables, then it delivers it in 1080-60i (and it looks way too smooth)
« Last Edit: December 03, 2012, 09:48:39 AM by HurtinMinorKey »

peederj

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #17 on: December 03, 2012, 10:52:24 AM »
Well the camera HDMI outs are 1080i60 and not progressive for whatever reason.

Thank you Jason for your detailed reports and example video. To test whether something is 420 or 422 I suggest shooting red & white text next to black & white text in the same frame, using text printed with enough resolution and zoomed out enough for its edge to be beyond the limit of sensor resolution. If the red & white (I actually like white on red, stop signs are often used for this) is significantly blockier looking than the black & white when zoomed 300% then you are at 420 but if it's close in resolution you are at 422. Equal in resolution would be 444. This way I have confirmed the HDMI out of the C100 is 422 and Canon announced the 5D3 clean HDMI firmware will indeed be 422.

422 is a bigger win than a lot of people seem to think, 420 is a massive thwack to color quality ime. If you only care about 720p web video then just shoot internal codec and be happy.

JasonATL

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #18 on: December 03, 2012, 11:04:37 AM »
peederj - In my test video, I looked for that. The resolution makes this a not-so-clear test. However, it does appear that there is a benefit to using the HDMI out in color resolution. Therefore, my best guess right now is that the current HDMI out is 4:2:2. And, I agree, having 4:2:2 is a very nice step up when trying to color grade or even add sharpness.

By the way, you can see the red effect that you describe in another video I did. It shows a way to greatly help with the type of blocking that you describe around red, especially when applying a sharpening filter. The solution is to use a very weak color blur filter prior to sharpening. https://vimeo.com/42314148

peederj

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #19 on: December 03, 2012, 12:02:11 PM »
By the way, you can see the red effect that you describe in another video I did. It shows a way to greatly help with the type of blocking that you describe around red, especially when applying a sharpening filter. The solution is to use a very weak color blur filter prior to sharpening. https://vimeo.com/42314148

Handy...thank you again Jason. The era of struggling with codecs and artifacts is thankfully coming to a close but we will still have situations where these techniques help. Educating each other about where this damage is coming from will put a lot of pressure on the manufacturers to fix it as we see with the 5D3 announcement. Canon wouldn't have given in on that last year.

LetTheRightLensIn

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #20 on: December 06, 2012, 02:36:05 AM »
HDMI is a data transfer protocol standard, just like TCP/IP or USB. And it's a dumb consumer-level standard...its professional sibling is called SDI. And on the C300 you get both options, and Atomos makes a higher end Ninja they call the Samurai that just does SDI instead of HDMI. HDMI was for HDTV, which for legacy reasons uses 1080i60, sending half the lines 30 times per second, alternating with the other half (all interlaced together) also 30 times per second. There is nothing a camera or anything else can do to alter the protocol...that's how the machines have all agreed to talk, and because it's so dumb a standard, you can expect any HDMI monitor or whatever to understand it.

But we don't want to shoot 30p or 60i (both are offered on the C100 btw), for cinema the standard frame rate is 24p, which gives a nice familiar texture and blur to motion when captured at a shutter angle of 180 degrees (1/48th of a second or 1/50th on the 5D3 is close enough). So how does one send a 24fps signal over a 60i protocol? I forget the technical term (you can google all of this of course, and please do) but they essentially just repeat frames alternating 3 repeats and 2 repeats to match the timing difference of 30:24. And the receiver, to deinterlace that redundant 1080i60 stream to 24p (23.98 is the actual rate on the Ninja also due to legacy concerns with synchronization) must figure out the cadence of repeats and drop the appropriate redundancies, leaving a steady and even stream of progressive frames.

The Ninja has to do this empirically off a moving image being sent so it can see which images are repeats and which are new and drop the proper ones. HDMI can't communicate that information sadly, meaning the Ninja waits with record disabled until it gets enough contrasty motion to see what to do.

As for your growth plans, I understand dipping your toe in, but a lot of this only makes sense when you have the full professional rig in front of you and understood, and then you can learn to make do with less. Good luck with your exploration however you go about it.

24p works perfectly fine over HDMI, many HDTVs handle 24p signals just fine and many computers and blu-rays players can output it as well as some gaming systems for disc output

you can send all sorts of signals over HDMI, my computer can send 1920x1080x60p over it too just fine


peederj

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #21 on: December 06, 2012, 10:14:22 AM »
Herp derp shows how much I know...  :o

But regardless of what's possible with HDMI, the Canons and external recorders are limited to 1080i60 8 bit 4:2:2, and a benefit of the Ninja is, given a sharp, contrasty signal to evaluate, it can deinterlace and pull down 23.98p out of it. With other systems (e.g. Blackmagic Hyperdeck Shuttle) you have to deinterlace and find the proper cadence to do the pulldown manually in post. Win for the Ninja.

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #21 on: December 06, 2012, 10:14:22 AM »

cayenne

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #22 on: December 07, 2012, 03:38:21 PM »
You know...

Just occured to me...this is all just DATA...wonder why there isn't some way to just stream off the image data via the USB port straight to computer or via a usb wireless dongle to a computer, and just bypass HDMI altogether?

Just a thought...

C

Policar

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #23 on: December 07, 2012, 04:58:53 PM »
You know...

Just occured to me...this is all just DATA...wonder why there isn't some way to just stream off the image data via the USB port straight to computer or via a usb wireless dongle to a computer, and just bypass HDMI altogether?

Just a thought...

C

USB2 has a theoretical maximum sustained transfer rate of 480mb/sec. In practice, it's closer to half that.

HDMI video (8 bit NTSC) is 30fps*1080 vertical pixels*1920 horizontal pixels*8 bit color*3 channels=about 1500mb/sec.

Way too much data.

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Re: Canon 5D3 - ML: Is Clean HDMI out working? Using it? Info...?
« Reply #23 on: December 07, 2012, 04:58:53 PM »