HV20 impressions
 

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

Thank you for your input Heinz. Your findings and contributions are important enough that you should consider starting a new thread within the "Canon HV10 / HV20 HDV Camcorders" area with the same imformation you just posted here. That way people will be on topic when they are interested in the information you've outlined - which I think is important information!

Cheers!

This news really bums me out. My major excitment over this camera was to capture uncompressed 24p to a micro-atx pc. I wonder if the issue will be able to be overcome with new Intensity drivers?

It looks like they released Intensity 1.3 today. Can anyone confirm that 1.3 does/does not work with the HV20?

I wouldn't be too worried about the Intensity drivers right now. I'm sure it is hard for Blackmagic to updated their product before the camera actually comes out. Now that some cameras are shipping I'm sure Intensity will be updated. I mean it makes no sense for them not to add support for the HV20 since this card is designed to work with HDMI ports on cameras and the HV20 is one of the few cameras to actually have this. The more cameras the card supports the more cards will get sold so I am sure support is right around the corner.

I'm not sure on this guys. But does this mean the footage that comes out of the HDMI port is prior to HDV MPEG2 encoding? Is it also prior to down rezing to HDV spec as well?

If someone could clarify that be great (if indeed someone has had the chance to test their cam yet).

Thanks for your efforts guys. Can't wait for the Aussie PAL one. DAMN IT HURRY UP CANON.AU. I'm getting a PS3 tomorrow and i really wanted to capture the HD moment in HD. lol :) no chance of that though. Not even listed on their site yet. *cries*

The signal the comes out of the HDMI port at the time of filming has to be uncompressed to avoid the delay caused by the HDV compression process. However, once the signal is recorded to tape and played back through the HDMI you are going to be getting a compressed signal because that is what is stored on the tape. Because the CMOS chip is full 1920x1080 you are also getting full resolution stream, until it goes to tape of course where it is scaled down for HDV.

Rob, i understand the processes etc of it. I was just wanting clarification specifically on the HV20 now some guys have them. i.e. are we getting the stream before full HDV compression (MPEG2 and pixel) and/or before pixel down sizing as well. Or is the HDMI port simply for playback of whats on tape. etc :)

Cheers

There is no HDV compression and no delay when capturing scenes with the HV20 using component or HDMI outputs. If the negotiation with the target capture device is correct, the HDMI output provides 8-bit RGB with 1920*1080i resolution. If this is the true 1920*1080 image from the sensor (after the initial DSP stage) or an upsampled version of the scaled down HDV image is not so easy to determine. There remains also the question, is the final output sampled in 4:2:2 or 4:2:0. Analysis of the captured frames may answer these questions.

Cheers

Agreed, therefore I have split these posts out from another discussion so that they stand as their own thread.

In the "HV20 1440x1080 or 1920x1080?" thread, I officially offer beers and hosting of the raw files for anyone wishing to post a res chart test of HDV vs Component vs HDMI. Or just HDV vs Component or HDV vs HDMI. Bonus beer if you test 24p vs 60i too...
http://www.dvinfo.net/conf/showthread.php?t=89603

Bruce Allen
www.boacinema.com

Hi Heinz,

thanks for this, also from me. I'm fascinated by your point (3) and the two test result JPEGs. How do you explain the higher noise levels in 1080i?

Thanks,
Pieter

oh, and any thoughts why the cyan falls short of the other gamuth extremes? Lighting or camera?
tnx

I'm a little confused, you're stating there's no HDV compression out the hdmi port and then saying you're not sure what output res and color sampling is being output. Does anyone know for sure here?

@Pieter

I assume its the lighting. The noise level may be affected by the fact, that in interlaced modes two independent fields are captured at different times. Also, the camera was a NTSC version, and there may be some modulation caused by interference with 50Hz light sources (here in Europe).

@Rich

The problem is, that the output of the single chip CMOS sensor (with bayer filter) is processed and enhanced by a DSP to generate the YCbCr output signal. The signal may be downscaled during this process or an additional resampling stage may be used. The HDMI interface provides an independent scaler to support different monitor resolutions.

I don't think that the real output resolution captured from the HDMI output is better than HDV. There are of course compression side effects, depending of image content and motion in the scene.

I have captured and analyzed a resolution chart using HDMI and HDV and compared the results, they are quite simular (see attachment).

The optical system (lens, focus etc.) is also limiting the bandwidth.

Regards
Heinz