HDMI monitoring on 5D3 in crop mode

[a.sintes]

Hi!

I really (really) enjoy shooting videos with my 5D3 using Danne's ML latest build and to be honest the only BIG missing feature for me currently to be completely happy is the incompatibility between crop modes (e.g.: 3.5K preset) and HDMI output so I'm unable to use an external monitor with a proper framed preview.

The question is: is there something we can do about it?
I really want to understand more how it works and eventually help to fix it if possible...

My current understanding is the ML developer's general approach of previewing video in LiveView and/or outputting in HDMI has been always first to try to do it the hard(ware) way by tweaking camera registers, which is very understandable as it may result in glorious real-time displays that are potentially very close to a proper framed preview.

Anyway, sometimes it's just not possible due to hardware limitations and this is why the current "framed preview" process in the 5D3 fallbacks to a 100% software way to do it, capturing the RAW buffer data window and displaying it by drawing pixels in the LiveView (YUV422 buffer feeding).

Of course this is not ideal because of the low CPU horsepower, so the framed preview is quite slow and with debatable quality (potentially switch to half horizontal resolution, in grayscale) in order to leave enough resources available for the RAW data writing itself, but at least it's always properly framed and usable enough (and I'm now convinced we can speed-up a bit this LV buffer feeding process using look-up-tables and pointer dereferencing - working on it).

My final question is then: is it possible to achieve an HDMI output process using the same software-only principle used for framed-preview?
Something like: when HDMI connection is detected, set the HDMI output to a fixed monitor-standard resolution (e.g.: 1280x720, YUV422) then use a software callback to create a properly framed image of this resolution from the RAW data buffer that will be streamed through HDMI (potentially disabling the LV display to increase performances).

Does this approach sounds possible or am I missing something?

I'm not at all comfortable with low-level registers stuff, but I can help in the pure software programming part (YUV framed image creation).

Thanks in advance for your insights.

[Bender@arsch]

https://www.magiclantern.fm/forum/index.php?topic=26851.msg242974

Maybe this will help you 😉

[a.sintes]

How so?
If I understood well, Bilal is typically using hardware specific methods to deal with realtime displays/HDMI on the EOS-M and other compatible cameras (DIGIC5), which remains currently unlocked on DIGIC5+ processors.
He said before that maybe he will try to dig more the 5D3 in the future but I don't know what's the current state of his work so I can only cross my fingers as it will be the best news possible!

[Mattia]

Hi! Noob question here: Is it possible to use the 5.7k 1:3 "anamorphic" mode with an external monitor? Do I need necessarily the 1.2.3 version installed?

There's written that the main advantage of the 1.2.3 version over the 1.1.3 is the "clean HDMI output", what does it mean? What's a "clean" HDMI output?

[Walter Schulz]

Clean: No overlays.
Another option new in 1.2.3: Dual-Display. Cam display can be used while external display is connected via HDMI.

[a.sintes]

That's it, and for your first question: yes and no -> yes it's compatible, but certainly not what you're (and I'm) expecting... what you will get no matter the preset/resolution you choose will be the equivalent of the "realtime" display in the HDMI output, meaning you cannot get a properly "framed" preview when exceeding 1080p native resolution.

This is why I'm wondering if we may be able to "redirect" the current "framed preview" image stream to the HDMI output.

[Mattia]

That's it, and for your first question: yes and no -> yes it's compatible, but certainly not what you're (and I'm) expecting... what you will get no matter the preset/resolution you choose will be the equivalent of the "realtime" display in the HDMI output, meaning you cannot get a properly "framed" preview when exceeding 1080p native resolution.

This is why I'm wondering if we may be able to "redirect" the current "framed preview" image stream to the HDMI output.

That's a shame.. Really the only thing missing in the 5d3 to be an incredible cinema camera is a good preview, maybe throught an HDMI display. I would like to help you but I'm no programmer nor an engineer, I'm just an humble videomaker! Maybe you could try to ask Bilal, have you tried writing him a message?

[a.sintes]

Bilal's already said before he will try to port what he did with his crop mood branch to the 5D3 (that may unlock this HDMI preview issue I guess, as it's an hardware tweak fixing LiveView, HDMI output being basically a duplication of it), but of course he never promised anything: it requires lot of personal time to investigate and it seems also the specific DIGIC5+ register values of the 5D3 are not at all the same he already unlocked on DIGIC5 cameras :-/

This is why I will try another approach which is more "software oriented" (I'm a sucker at reverse engineering and low-level register tweaking...) by trying to reuse what I did with the ultrafast framed preview for LV buffer feeding and simply "redirect" the image to the HDMI output using a fixed standard resolution, if it's possible.

What I "just" need currently to figure is how to programatically:
1. set the HDMI output to a given resolution when a cable is connected
2. get some kind of pointer to the HDMI buffer to be fed (YUV422, I guess)

I agree this is currently my #1 missing ML feature to be happy in the next 10 years with my 5D3, and I would be satisfied enough even if I only get a low resolution grayscaled image on my HDMI monitor, if it's at least properly framed when using crop modes!

[vastunghia]

+1 a.sintes, that would be a major leap for 5D3 users