1080/60i 4:2:2 HD-SDI output

Troy Aitken · February 16th, 2008, 08:08 AM

So if the sensor is only 1440x1080, then HD-SDI 4:2:2 8bit colorspace is actually uprezed and not true. I thought the physical size of the sensor was 1920x1080 1/3". Threads that I have read state the H1 as a higher rez (by sensor) than Sony or Pani, not including the EX Sony.
Also, I understood the HDV standard is 1440x1080 4:2:0.

Is this true?:

Canon compresses the signal captured by the sensor (1920x1080 4:2:2) to HDV 1440x1080 4:2:0 to tape. Therefore the signal is resampled to fake that compressed resolution and colorspace to be interpolated to stretch and fill a 1920x1080 4:2:0 colorspace when sent to computer by SDI.
If this is the case would there not be an issue with artifacts and banding? Why is the signal much better when output to Blu-ray? If the resolution is not there, then it cannot be stretched and produce a cleaner and better result. My workflow as mentioned earlier in this thread also seems to have more color info as the signal results in an uncompromised gradation in the colores from dark to light w/o banding. In theory according to what is being said here this should not be so. Only in pure HD-SDI 4:2:2.

Finally, I have read the HDV standard, read lit on Canon and I see no specifications stated anywhere as to what is truely going on.

Thanks to all for patience as I try to get a clear understanding in a theory or factual statements that back up my obvious results.

thx
troy

Troy Aitken · February 16th, 2008, 08:27 AM

http://dvinfo.net/canonxlh1/articles/article06.php

just found this article by Chris

Peter Moretti · February 16th, 2008, 02:31 PM

Troy, uprezing performed by the camera can make the picture look better. One very concrete reason is that your NLE will recognize the color as 10-bit, even though only 8 bits are significant. But during color corrections, those additional two bits are used when storing the new color values. So while you start out with eight bit color, the various color effects you add are not limited to 8 bits but are rather allowed to expand to ten bits.

HDV uprezing by the camera will not look as good as uncompressed, but it is entirely possible that it looks noticeably better than HDV.

Those who say you can't get more than what you put in are not being entirely accurate. Uprezing in one form or another is beneficially used in video all the time. Examples include pixel shifting and in camera sharpening. They do actually improve what you put in. In fact, many forms of digital signal processing that the camera performs are variants of uprezing.

You discovered a good improvement over just using HDV directly into the NLE ;). And people are noticing similar results with the HV-20 capturing HDV out of the HDMI port instead of the Firewire one. So I have no reason to doubt what you're saying. It makes sense.

Of course, uncompressed will look considerably better.

Troy Aitken · February 16th, 2008, 08:57 PM

Cool!

That works for me. Thanks alot, I appreciate it.

Best Regards,
Troy

February 16th, 2008, 08:08 AM	#31
Troy Aitken New Boot Join Date: Jul 2005 Posts: 23	hd-sdi vs. tape cont..... So if the sensor is only 1440x1080, then HD-SDI 4:2:2 8bit colorspace is actually uprezed and not true. I thought the physical size of the sensor was 1920x1080 1/3". Threads that I have read state the H1 as a higher rez (by sensor) than Sony or Pani, not including the EX Sony. Also, I understood the HDV standard is 1440x1080 4:2:0. Is this true?: Canon compresses the signal captured by the sensor (1920x1080 4:2:2) to HDV 1440x1080 4:2:0 to tape. Therefore the signal is resampled to fake that compressed resolution and colorspace to be interpolated to stretch and fill a 1920x1080 4:2:0 colorspace when sent to computer by SDI. If this is the case would there not be an issue with artifacts and banding? Why is the signal much better when output to Blu-ray? If the resolution is not there, then it cannot be stretched and produce a cleaner and better result. My workflow as mentioned earlier in this thread also seems to have more color info as the signal results in an uncompromised gradation in the colores from dark to light w/o banding. In theory according to what is being said here this should not be so. Only in pure HD-SDI 4:2:2. Finally, I have read the HDV standard, read lit on Canon and I see no specifications stated anywhere as to what is truely going on. Thanks to all for patience as I try to get a clear understanding in a theory or factual statements that back up my obvious results. thx troy

February 16th, 2008, 08:27 AM	#32
Troy Aitken New Boot Join Date: Jul 2005 Posts: 23	hd-sdi vs. tape cont..... http://dvinfo.net/canonxlh1/articles/article06.php just found this article by Chris

February 16th, 2008, 08:57 PM	#34
Troy Aitken New Boot Join Date: Jul 2005 Posts: 23	Hd-sdi Cool! That works for me. Thanks alot, I appreciate it. Best Regards, Troy

February 16th, 2008, 02:31 PM	#33
Peter Moretti Trustee Join Date: Mar 2007 Location: Sherman Oaks, CA Posts: 1,259	Troy, uprezing performed by the camera can make the picture look better. One very concrete reason is that your NLE will recognize the color as 10-bit, even though only 8 bits are significant. But during color corrections, those additional two bits are used when storing the new color values. So while you start out with eight bit color, the various color effects you add are not limited to 8 bits but are rather allowed to expand to ten bits. HDV uprezing by the camera will not look as good as uncompressed, but it is entirely possible that it looks noticeably better than HDV. Those who say you can't get more than what you put in are not being entirely accurate. Uprezing in one form or another is beneficially used in video all the time. Examples include pixel shifting and in camera sharpening. They do actually improve what you put in. In fact, many forms of digital signal processing that the camera performs are variants of uprezing. You discovered a good improvement over just using HDV directly into the NLE ;). And people are noticing similar results with the HV-20 capturing HDV out of the HDMI port instead of the Firewire one. So I have no reason to doubt what you're saying. It makes sense. Of course, uncompressed will look considerably better.