HV20 Impressions -- HDMI etc.

[Heinz Bihlmeir]

Originally Posted by Ali Husain

thanks for doing that test! it makes sense since, in a static scene, only the color resolution is different between hdv and hdmi, correct?

Yes, the vertical chroma resolution is better when the signal is captured via hdmi (hdmi:422, hdv:420).
If the handshake with the hdmi display succeeds, the 1440*1080 420 image is upconverted to a 1920*1080i 444 YCrCb format, else the image is downconverted to 480p RGB (DVI).

[Patrick Jennings]

can you clarify...

is the live signal coming out of the HDMI port is 1440x1080 4:2:2 upscaled to 1920x1080 4:2:2?

so it isn't true 1920x1080?

[Ali Husain]

for problem #1 below, i filed a ticket with blackmagic and sent them a link to this thread. they responded and said they will check this out. thanks heinz for the testing!

Originally Posted by Heinz Bihlmeir

Hi there,

if anyone is interested, I uploaded some HV20 still images to Mediafire. The images are captures from an uncompressed video stream (8-bit 1080i59) recorded from the analogue component output of the camera, bypassing the HDV compression. The same shots taken from a HC1 are also included for comparision.

There are some minor problems, I encountered when playing around with the camera.

(1) HDMI port does not work with currently available capture hardware.
When connecting to a BM intensity card, the HDMI output falls back to DVI
mode and scales down to 480p. A HD-Connect MI converter maintains the correct resolution but seems to output the wrong colorspace (RGB instead of YCrCb).

(2) When zooming in aufofocus mode, the camera gets out of focus
and then becomes sharp again continously. This is not a compression side effect, the behaviour is also visible in the uncompressed signal.
Best solution is to switch off aufofocus during zoom recording
(see hv20_zoom1-4.jpg).

(3) When switching to 24p, the image becomes brighter and it seems that also the gamma is affected. As expected there is also an increase in SN ratio. When returning back to 60i the brightness remains at the same level. There seems to be no loss in resolution between 60i and 24p modes.

(4) I miss a color bar function. I have included a 1920*1080 jpeg image which can be put on the camera SD card to ease calibration of a monitor during playback (img_0101.jpg).

Link to the zip archive: www.mediafire.com/?ad3yjrjjwjg File: hv20caps.zip

Regards,

Heinz Bihlmeir

[Heinz Bihlmeir]

Originally Posted by Patrick Jennings

can you clarify...

is the live signal coming out of the HDMI port is 1440x1080 4:2:2 upscaled to 1920x1080 4:2:2?

so it isn't true 1920x1080?

No it isn't, this is my conclusion interpreting the results of my measurements (see attachment posted earlier in this thread).

Btw: The HD-Connect MI HDMI->HDSDI converter works now with the HV20 in the correct color space (fw 1.1.35).

Regards,
Heinz

[Pat Reddy]

Ken, I have noticed some instant autofocus "peculiararities" on my HV20. The manual specifically recommends turning off IAF if you are shooting through a window pane. I was filming a scene through my living room window the other day with a slow zoom to telephoto, and the trees outide were rapidly pulsing in and out of focus. Yesterday, I was filming elk in a meadow at sunset. While panning rapidly in full telephoto, the trees on the horizon were pulsing rapidly in and out of various degrees of focus.

In one case, I was using IAF in a situation that the manual cleraly states will cause problems. In the other, I was panning so rapidly that the footage would have been unuseable anyway.

In normal use I have found the IAF to be excellent. I wonder if there is some middle ground between the idea that some of these units are defective and the likelihood that there are some situations for which normal autofocus is a better choice. The camera provides you with the option to use either. No setting on the camera will allow it to "read your mind" and discern exactly how you want your footage to look. Even in normal autofocus this camera locks onto focus more accurately and decisively than my HC1. Since IAF is so agressive, perhaps there are simply times when you will want to use normal autofocus instead.

Pat

[Ken Ross]

Pat, virtually all of the conditions you cited are extremely difficult for any autofocus. Shooting through glass is a situation always mentioned in any manufacturer's camcorder instruction manual. You may be better off using manual focus for that. The other condition you mentioned is also very rare and something you should generally avoid for a number of reasons. It's not good practice to pan while at full zoom. First off no viewer wants to watch that kind of video...it's dizzying. Secondly, the autofocus just won't work properly. If your subject distance is the same while you do those full zoom pans, you're far better off using manual focus and leaving it there.

That would be true with any cam. You just have to come to a reasonable expectation of what any of these systems can and can't do. But feel good in the knowledge that the Canon Instant Autofocus is probably the best system out there.

[Pat Reddy]

I absolutely agree with everything you just said. My only point is that IAF is something new. Since it can agressively achieve focus in situations that challenge normal autofocus, users may sometimes see it going in and out of focus and think that there is something wrong with the camera, when there is not. (My only reason for recording a rapid pan was that I didn't want to shut the recording off while I tried to catch an elk briefly in view in an area free of distracting foreground clutter.)

Pat