View Full Version : Resolution of signal from HDMI


James Donnelly
February 2nd, 2011, 04:47 PM
Hi,

Well, this is strange. I have read in numerous places that the 550d outputs 1080i while in live view over the HDMI port, albeit only when not recording, which then causes it to switch to 480p.

I just plugged my 550d into an LCD monitor via a HDMI to DVI adapter, and the monitor is reporting 480p under all conditions, video mode, both recording and not recording and also stills mode with live view on.

I have toggled all the modes via the 'disp' button. Also, the image has a border. Could this be because the monitor is doing underscan or something?

Cheers.

Jackson Hager
February 2nd, 2011, 05:14 PM
I wish my monitor did that! Mine is SD, and the switch from widescreen to 4:3 between liveview and recording causes all sort of headaches for me. I can choose to preview everything all stretched, or record everything all squished, or spend the first 15 seconds of every take going through the menus to change aspect. And DVI sucks pretty bad too, only using about 60% of screen real estate (widescreen inside standard inside widescreen).

You should make sure your monitor set to HDMI and not DVI. What you have sounds like DVI.

Steve Oakley
February 2nd, 2011, 06:29 PM
the only difference between HDMI and DVI is that HDMI mode will send audio if the monitor has speakers. it simply sounds like your monitor only likes 1080i while the 550D is in fact putting out 1080P which not all monitors will take. then the camera / monitor talk to each other to find a format that can work which sounds like only 480 in your case. solution : new monitor

Jackson Hager
February 2nd, 2011, 07:31 PM
I don't know, Steve. HDMI and DVI look totally different on my monitor. Even the layout of the Canon menus is different (and yes, I know to press DISP to change them). It looks to me like DVI is 640x480 or something. At least for me.

HDMI: http://i.imgur.com/FLCBV.jpg

DVI: http://i.imgur.com/My85s.jpg (output appears to be 16:9 fit into 4:3. You can see the lighter square where the camera is outputting information.)

Plus, DVI doesn't hiccup or change resolutions when I start recording, as HDMI does. This leads me to conclude that they are not in fact the same output.

Also, output in liveview on the T2i is 1080i, not 1080p.
http://i.imgur.com/v75wO.jpg

James Donnelly
February 3rd, 2011, 03:59 AM
the only difference between HDMI and DVI is that HDMI mode will send audio if the monitor has speakers. it simply sounds like your monitor only likes 1080i while the 550D is in fact putting out 1080P which not all monitors will take. then the camera / monitor talk to each other to find a format that can work which sounds like only 480 in your case. solution : new monitor

Monitor supports 1080p. Are you 100% certain the Camera can adjust its output resolution if the monitor can't sync? How does it know? This sounds like an unlikely suggestion to me, but I'm happy to be proved wrong.

I don't know, Steve. HDMI and DVI look totally different on my monitor. Even the layout of the Canon menus is different (and yes, I know to press DISP to change them). It looks to me like DVI is 640x480 or something. At least for me.

HDMI: http://i.imgur.com/FLCBV.jpg

DVI: http://i.imgur.com/My85s.jpg (output appears to be 16:9 fit into 4:3. You can see the lighter square where the camera is outputting information.)

Plus, DVI doesn't hiccup or change resolutions when I start recording, as HDMI does. This leads me to conclude that they are not in fact the same output.

Also, output in liveview on the T2i is 1080i, not 1080p.
http://i.imgur.com/v75wO.jpg

My guess is that by DVI you mean the SD output from the USB port? If so, this is not what we're talking about. DVI refers to the interface for digital video used by computers which carries the same format of video signal as HDMI, minus the audio.

I also understood the output of the HDMI port to be 1080i.

James Donnelly
February 3rd, 2011, 05:27 AM
Steve,

Thought I would do some more reading about your point.

I was not aware that resolution negotiation was possible when going from HDMI to DVI, but it seems this is exactly what should be going on as HDMI is a super set of DVI.

In light of this, given that my cable seems to support 1080i from my camcorder (HF100), it does seem probable that the monitor doesn't like the signal from the 550d, so it looks like you were right.

It doesn't matter, as actually I'm just testing on my computer's LCD monitor at the moment (native 1920x1080), and looking at my options for capture cards and field monitors.

I'm keen to see if ML now facilitates clean 1080i, as it seems with the version I'm using, I can get rid of the white box.

Cheers,

James

Russ Ivey
February 3rd, 2011, 09:40 AM
Hey James, I know your pain. My monitor does the same thing with the 550D. It looks great before recording, but records in lower resolution. I'm sure you already know this, but thought I would throw it out there: Hopefully you've already set up your camera before hitting record, so it's not ALWAYS a necessity to have it in HD when recording. I am not certain if I'm misunderstanding or not, but I thought that Magic Lantern was looking at coming up with a build that will support keeping it at HD when in record mode? I could be wrong.

James Donnelly
February 3rd, 2011, 11:32 AM
Hey James, I know your pain. My monitor does the same thing with the 550D. It looks great before recording, but records in lower resolution. I'm sure you already know this, but thought I would throw it out there: Hopefully you've already set up your camera before hitting record, so it's not ALWAYS a necessity to have it in HD when recording. I am not certain if I'm misunderstanding or not, but I thought that Magic Lantern was looking at coming up with a build that will support keeping it at HD when in record mode? I could be wrong.

I want to get 1080i out when not recording.

I'm aware of reports that the resolution of the HDMI output jumps from 1080i to 480p when recording is activated, but I have a different issue, I can't get 1080i in the first place.

As far as I understand the situation with ML, we are never going to get 1080 out when recording is going on. Trammel gave a good explanation of why during his recent interview, although he didn't rule out one of the other ML wizards (AJ) finding a way.

Jackson Hager
February 3rd, 2011, 12:27 PM
I just meant switching the monitor from "HDMI" to "DVI" with the HDMI cable plugged in. It goes from widescreen to standard aspect ratio. Video out with the USB to a normal yellow RCA cable is something I've tried, but the analog signal really isn't up to par in terms of quality or smoothness when moving.

For me, I think the perfect solution would be to have 480p out all the time from my 550d, whether recording or not. Since I don't an HD monitor anyway, and don't want to record the HDMI output. That way, my monitor would not get all funky with aspect ratio changes. That seems like something the ML guys could pull off. probably easier to get SD out all the time than HD out all the time. Don't know how many people would want it besides me though...

James Donnelly
February 3rd, 2011, 03:33 PM
I just meant switching the monitor from "HDMI" to "DVI" with the HDMI cable plugged in. It goes from widescreen to standard aspect ratio. Video out with the USB to a normal yellow RCA cable is something I've tried, but the analog signal really isn't up to par in terms of quality or smoothness when moving.

For me, I think the perfect solution would be to have 480p out all the time from my 550d, whether recording or not. Since I don't an HD monitor anyway, and don't want to record the HDMI output. That way, my monitor would not get all funky with aspect ratio changes. That seems like something the ML guys could pull off. probably easier to get SD out all the time than HD out all the time. Don't know how many people would want it besides me though...

Ok I understand better now, so if you switch modes on the monitor without relocating the cable, it changes behaviour? Hmm maybe this is something to do with my issue.

I'm pretty sure you have more chance of getting 480 constantly than 1080, as I don't think there is the horsepower to do 1080 during recording. However, ML can only do so much at the moment, because there is no way of making wholesale changes to the functioning of the DIGIC as things stand because of lack of documentation.

I think you're far from alone in your wish for an interruption free switch into recording mode, as I've heard many people bring this up.

James Donnelly
February 10th, 2011, 04:31 PM
the only difference between HDMI and DVI is that HDMI mode will send audio if the monitor has speakers. it simply sounds like your monitor only likes 1080i while the 550D is in fact putting out 1080P which not all monitors will take. then the camera / monitor talk to each other to find a format that can work which sounds like only 480 in your case. solution : new monitor


Another follow up. The monitor states in the manual that it supports both 1080i and 1080p, and I can see it operating at these settings from other sources.

I presume it must be the HDMI -> mini HDMI cable I'm using.

Pedanes Bol
February 10th, 2011, 07:19 PM
What resolution does your LCD monitor show on playback mode? (When you play a movie recorded in the camera).

James Donnelly
February 11th, 2011, 06:40 AM
What resolution does your LCD monitor show on playback mode? (When you play a movie recorded in the camera).

Same, 480p. My understanding is the camera tried to use the same mode for non-record live-view and playback, but I did check to see if playback gave me 1080i.