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-   -   Here's a question for you. (https://www.dvinfo.net/forum/canon-xh-series-hdv-camcorders/490810-heres-question-you.html)

David Rice January 27th, 2011 05:53 PM

Here's a question for you.
 
I was looking at the A1 specifications and I found that the HD and SD(16.9) have the same frame size, resolution and pixels.

HD approx. 1.56 Megapixels (1440 x 1080)
SD (16:9) approx. 1.56 Megapixels (1440 x 1080)

They are identical
.

So if I shoot SD (16.9) or HD the quality and file size are the same?

Is this correct? It sure looks that way to me.

Now standard SD SD (4:3) approx. 1.17 Megapixels (1080 x 1080) is not the same. So I'm presuming that the A1 down converts HD or SD (16.9) to create Standard SD (4.3). Correct?

OK,
So why not shoot SD (16.9) instead of HD, since SD (16.9) would be easier and faster to edit?

????

Peter Manojlovic January 27th, 2011 10:02 PM

Quote:

Originally Posted by David Rice (Post 1612022)
I was looking at the A1 specifications and I found that the HD and SD(16.9) have the same frame size, resolution and pixels.

HD approx. 1.56 Megapixels (1440 x 1080)
SD (16:9) approx. 1.56 Megapixels (1440 x 1080)

Not sure about the interpretation, or what's been quoted,..... but in the end, SD is going to be 720x480 pixels, regardless of how much the sensor uses internally...
Wheras HDV will output to 1440x1080 pixels...

David Rice January 27th, 2011 10:09 PM

I just double checked on the Web Site for the A1s. As per their own specs, the camera delivers SD (16:9) approx. 1.56 Megapixels (1440 x 1080).

??????

Chris Soucy January 27th, 2011 11:07 PM

Hi, David...........
 
Not really my area of expertise, but I'l have a stab at this one, if I may.

I think where this all falls apart is between what the front end can aquire, and what the back end can write to tape, to keep within spec.

The DV spec is pretty specific about what goes on the tape, the compression used and many other thngs as well.

During the front end to back end journey, that aquisition has to be whittled down to what the DV spec allows on the tape, which is 720 X 480 pixels max, no matter what was taken in at the front end.

Does the camera put out a higher resolution picture via the Firewire port during DV capture than is written to tape?

Doubt it, otherwise any system designed for DV wouldn't be able to reckognise it, so it must be down sampled before it gets to that port.

In short, no matter what the specs say, what is going in, is NOT what is coming out, as it MUST be DV compatible in SD mode.

The overall bandwidth used during tape record of both SD and HD is pretty much identical, but there is a huge difference in the compression between the systems, which explains why the data rate is similar even though the data retrieved after is so much higher in HD.

As to your specific question about shooting SD or HD to get editable SD footage, there are about 5,000 posts here that basically say the camera doesn't do as good a job of converting HD to SD as can be achieved in pretty well any decent NLE, so why shoot SD?

If you're pushed for processing power or time, fine, shoot SD. Nearly everyone as posts on the subject say they get better results shoting HD then down converting.

Heck, I'm not going to argue, I've never shot SD on the camera since I've had it.


CS

Bo Sundvall January 28th, 2011 03:04 AM

Hi

Don't know what they mean with the SD resolution, it seems as the info you attatch is taken out of it's circumstances. To make it possible for us to help you must show more of the document or attatch a link to it.

SD can never be HD resolution. A guess is that Canon mean that the whole CCD is used to capture SD. The picture will then ALWAYS be down converted to SD resolution, 720x480 (NTSC) or 720x576 (PAL) and stored that way on tape.

Regards,

/Bo

Les Wilson January 28th, 2011 08:06 AM

David,
I agree with Chris' explanation. THe camera is using the whole sensor in SD 16:9 mode but down sampling it to standard DV format (720x480 anamorphic). You can prove this by recording to your MRC1K or to your computer directly. The resulting files will be 720x480 anamorphic.

David Rice January 28th, 2011 08:42 AM

Then with the A1 there is no way to utilize the highest capabilities of the senor.

Bo Sundvall January 28th, 2011 08:56 AM

Yes there is. Shoot HDV (1440x1080). If you have need for SD, downconvert in post, nobody will see the difference.


Regards,

/Bo

Peter Manojlovic January 28th, 2011 08:48 PM

"Then with the A1 there is no way to utilize the highest capabilities of the senor. "
Yes there is..Learn about lighting and composition...


David.....

If you're planning on outputting to DVD, then stick to SD 16:9..It will save you the headaches of getting a downconvert..
If you're planning on delivering to BluRay or HD web, the stick to HDV 30fps ...

Don't let the theoretical assumptions get in the way of having fun...
Trust us on this...Go out and shoot!!!

David Rice January 28th, 2011 09:57 PM

I'm shooting HD 30p. I have a friend looking for a backup camera and I suggested he purchase a used A1. That's when we read the A1s specs and noticed that the camera does SD (16:9) at approx. 1.56 Megapixels (1440 x 1080). Why Canon lists it like this in it's specs, I have no idea.

All it does is add to confusion.

Garrett Low January 28th, 2011 10:14 PM

Quote:

Originally Posted by Peter Manojlovic (Post 1612497)
If you're planning on outputting to DVD, then stick to SD 16:9..It will save you the headaches of getting a downconvert..
If you're planning on delivering to BluRay or HD web, the stick to HDV 30fps ...

I would actually advise against this. As has been already pointed out, the XH and XL canons use the full sensor at all times, whether shooting HD or SD. In order to create an SD picture, it relies on in camera resampling to create the SD signal. The camera just does not have enough computing power to do a good job at this. Go back and read many posts on disappointed XH A1 owners who were shooting SD and couldn't figure out why their SD footage looked so bad, yes, even with good lighting.

You will get far superior results if you shoot HD and use a quality down converting program such as VirtualDub (which is free) to get your SD footage. Most NLE's do a horrible job at resizing video, FCP, Adobe, and Sony Vegas are some of the worst. Yes, there is a longer workflow but it is worth it. I'd advise that you experiment for your self as I did.

-Garrett

Tom Hardwick January 29th, 2011 09:30 AM

Quote:

Originally Posted by David Rice (Post 1612505)
the camera does SD (16:9) at approx. 1.56 Megapixels (1440 x 1080). Why Canon lists it like this in it's specs, I have no idea. All it does is add to confusion.

There's no confusion David. The camera is permanently and always 1440 x 1080. The chips are 1440 x 1080. You can choose to record this to tape as HDV or you can 'shoot in DV' and record 720 x 576 (or 480) to tape.

Of course in this SD mode the camera is still shooting 1440 x 1080 (it's forced to when it's fitted with these chips) it's just that it does the down-conversion from HDV to SD on the fly, between chips and tape.

tom.

Mark Fry February 3rd, 2011 11:18 AM

Quote:

Originally Posted by Garrett Low (Post 1612508)
You will get far superior results if you shoot HD and use a quality down converting program such as VirtualDub (which is free) to get your SD footage. Most NLE's do a horrible job at resizing video, FCP, Adobe, and Sony Vegas are some of the worst. Yes, there is a longer workflow but it is worth it. I'd advise that you experiment for your self as I did.

There is at least one NLE that does a good job of down-converting HDV to SD: Avid (used to be Pinnacle) Liquid (v7.2). I've been using it for 4 years and have had the chance to compare DVDs I've made with those made by Adobe, FCP and Sony Vegas systems. Liquid does seem to do a better job.

(Liquid is a bit of a "legacy" product now. It's cheaper, easier to use and all-round better than Avid's own Media Composer, so they've stopped developing it - IMHO, of course!! ;-) Therefore, I keep my eye out for alternatives. I haven't found one yet that makes better DVDs from HDV.)

Jan Luethje February 3rd, 2011 06:16 PM

I'm using the A1 and AVID, mostly for SD productions, and this since roughly four years. I tested both ways quite thoroughly, shooting HDV and downconverting, as well as shooting in SD and going straight forward. May be I'm blind and dumb, but I couldn't figure out a significant difference. If you tweak the settings right, the A1 will give you great SD images right away. And you don't waste time with downconverting.

Garrett Low February 3rd, 2011 06:47 PM

Quote:

Originally Posted by Mark Fry (Post 1614251)
There is at least one NLE that does a good job of down-converting HDV to SD: Avid (used to be Pinnacle) Liquid (v7.2). I've been using it for 4 years and have had the chance to compare DVDs I've made with those made by Adobe, FCP and Sony Vegas systems. Liquid does seem to do a better job.

I have not used Avid for ages (never with HD footage, that shows you how long) but I have heard it does a better job than the others. As I mentioned VirtualDub does a very good job and allows you to chose from a number of resizing algorithms. For HD to SD I usually use the Lanczos algorithm as it retains the sharpest looking PQ.

Quote:

Originally Posted by Jan Luethje (Post 1614370)
I'm using the A1 and AVID, mostly for SD productions, and this since roughly four years. I tested both ways quite thoroughly, shooting HDV and downconverting, as well as shooting in SD and going straight forward. May be I'm blind and dumb, but I couldn't figure out a significant difference. If you tweak the settings right, the A1 will give you great SD images right away. And you don't waste time with downconverting.

Jan, what settings are you changing to improve the SD quality. I no longer shoot with an XH A1 but when did I spent a long time trying to tweak settings and nothing I tried could make it look better than shooting HD and downresing.

-Garrett


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