Correct resize of DV Pal video (720 -> 768)

Question

Correct resize of DV Pal video (720 -> 768)

Hello!

I'm using a DV cam (Pal standart). The DV video is 720x576 NON-square pixels.
To display it on a computer monitor the correct size is 768x576 pixel, because these are square pixels.

Ok! But the actual used video area is only 704x576 pixels, because DV cams don't use the 8 left/right -most pixels (=black bars).

So, do I have to resize the video 720 -> 768 and keep the black bars or to resize it 704 -> 768 without the black bars???????????????

Of course I want the resulting video to reproduce the original scene with the right aspect ratio (e.g. a perfect sphere should be a perfect circle (no ellipse) in the end)!

(One thing: Please read the question carefully and don't respond if you don't know what you are talking about - its pretty annoying to get wrong or of topic half-cocked answers.)

Cheers

Barlock

G5 Dual 2GHz, 8 RAM-Slots, Mac OS X (10.3.9), 2GB, 360GB, Radeon 9650

Posted on Jun 29, 2006 8:26 AM

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Answer 1

Top-ranking reply

Studio X

Level 7

27,229 points

Jul 18, 2006 8:28 AM in response to Immortal Balrock

The sonys sometime do not write to the full width. The black edges will be in the overscan area anyway and will not be seen. The sequence format is still 720 and that is what will be output.

If you want to do color correction for TV you DO NOT want to use a video card out. Find yourself an inexpensive DV/Analog converter (Canopus 55 or 110 come to mind) and use that to connect to a Broadcast monitor. Standard TVs are not calibratable and do not hold settings. They also do not allow you to check the overscan area.

A little civility will carry you much further on this board.

Over and out.
x

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Answer 2

Jun 30, 2006 9:39 AM in response to Immortal Balrock

Dear Immortal,

I always take a moment before hitting the "post" button, here and consider whether I'm adding anything worthwhile. And many's the time, I've decided to go ahead even though I'm not sure and given someone the clue they need to solve their problem. I've got a few ideas for you, but really don't want to annoy you.

Michael

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Answer 3

Jul 3, 2006 1:19 AM in response to Michael Grenadier

Hi Michael!

Its good that you think about what you are doing 😉

I posted this note at the end, because I got answers to other questions from people which didn't get the point of actual question.

This happend more than one time and these people also tend to post the exact same nonsense again even when I posted a refined question.

Anyway, thanks for posting nonsense, too.

If you have something to answer my question, I would be happy if you post it...

...otherwise, I don't need your comment (thats exactly why I added this note to the original post).

At least you read that part of my post carefully 😉

Cheers

Balrock

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Answer 4

mooblie

Level 4

1,954 points

Jul 3, 2006 6:22 AM in response to Immortal Balrock

I would suggest that all 720 pixels ARE active in DV: for example: if you do a frame grab, there are no black bars down the side of your 720x576 frame.

I suppose it might depend on your camera sourcing the footage, but do YOU see black bars anywhere in your frame?

Perhaps a scientific way to determine this would be to record a large circle (from a camera) and measure the geometry after capture and horizontal scaling at different degrees (720 to 768 and 704 to 768) and determine which result gives the more accurate final aspect ratio?

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Answer 5

Jul 17, 2006 4:17 AM in response to mooblie

Hello mooblie!

Thanks for your post.

Yes, I do see black bars.

The difference from 720 to 704 is very small, so I don't know if its possible to measure the distortion if one uses the wrong resizeing method? (But at the moment, I don't have time to try)

Anyway, there should be a clear definition, which part of the picture has to be rezied!

Cheers

Balrog

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Answer 6

Jul 17, 2006 4:34 AM in response to Immortal Balrock

If you resize to 704x576 you are changing the aspect ratio of the original source material. The black either side of the frame is a part of the image and you should not try and aspect correct these pixels out of the image.

I am confused as to why you need to aspect correct for your monitor... 720x576 displays perfectly on my computer monitors. If you are concerned, why don't you monitor with an external broadcast monitor?

S

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Answer 7

Jul 17, 2006 5:49 AM in response to stevemacirl

Hi!

If you display 720x576 on a computer monitor (square pixels) the image is distorted!
The correct size would be 768x576 (which is true 4:3).

I want to use my TV as a controll monitor but still have problems setting up a PCI video card (with S-Video out) in my G5 😟

I was looking for a technical answer - you can easily be fooled by your eyes.

Cheers

Balrog

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Answer 8

Jul 17, 2006 6:03 AM in response to Immortal Balrock

Is this a FCP question? There are no issues that I am aware of in FCP that affects the display of 720x576 or 768x576, all aspects display as acquired. Are you using something other than FCP for playback? Could it be that it is you who doesn't know what he is talking about?

S

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Answer 9

Jul 18, 2006 3:03 AM in response to stevemacirl

Hello stevemacirl!

I'm posting my question here, because this is the FC "PRO" board!

Read the original question and especially the last part, that I wrote only for people like you.

Be silent!

(I want to know how things work - I don't care if an application does it automatically)

balrog

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Answer 10

Jul 18, 2006 3:44 AM in response to Immortal Balrock

Steve is right. Final Cut Pro will correct the display of rectangular PAL pixels with no trouble. Can you imagine if every time anyone wanted to edit video they had to manually resize it and wait for it to render? Nothing would ever get done.

If you start messing around with the pixel dimensions you're only going to cause trouble... in Final Cut Pro. You'll only have a pixel-aspect ratio problem if you want to display your videos on a computer outside of FCP. Is that part of your workflow?

Every PAL DV camera I've shot with has utilized all 720 pixels across. What camera are you shooting with?

And you shouldn't need to setup a PCI card in order to monitor DV from FCP. If you hook up your camcorder to the computer via firewire and hook up the camcorder to your monitor then you can turn on "external video" in FCP and you should have no trouble.

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Answer 11

Jul 18, 2006 6:09 AM in response to Kyle Gilman

It would appear the Immortal Balrog hasn't got a bull's notion of what he is at and therefore should be a little more humble about using the FC "Pro" forum to seek the assistance of other users.

His ignorance of pixel aspect ratios is not uncommon and I'm sure we all like to share our knowledge but his attitude when seeking help is downright ignorant.

S

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Answer 12

andynick

Level 5

4,955 points

Jul 18, 2006 6:49 AM in response to stevemacirl

> his attitude when seeking help is downright

ignorant.

I'll second that, stevemacirl . . .
If you want help here, Mr Immortal, it'll pay you to show a little more respect to those who are trying to help you.

Andy

G5 Quad. 8 GB. 250 & 500 GB Internal HDs. G-Tech G-Raid 1 TB. FCP 5.0.4 (Studio) Mac OS X (10.4.7) Sony HVR-Z1E.
You can't educate pork . . ..

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Answer 13

Jul 18, 2006 7:28 AM in response to Kyle Gilman

Hi Kyle!

I'm using a Sony VX1000 (Pal) and I see black bars (8 pixels wide) on each side of the image (so the active video area is only 704 pixels wide).

I haven't unlocked the DV-in option and I don't want to use the camera as a video output. I goint to install a second video card (ATI 7000 PCI) in my Mac and connect my TV via the S-Video output.

Cheers

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Answer 14

Jul 18, 2006 7:39 AM in response to Immortal Balrock

You haven't unlocked the DV-in option? What does that mean? How are you capturing the video? A VX1000 should not have black bars on the side if you capture through firewire, which you should do. It should use all 720 pixels across and should not require any resizing or rendering. If you're doing it any other way you should recapture through firewire.

And you'll get SIGNIFICANTLY higher quality video if you use your camera for video monitoring. Several orders of magnitude better. Using a graphics card with an s-video is not a workable solution. Why don't you want to use the camera for video output? It doesn't hurt it or anything.

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Answer 15

Jul 18, 2006 8:14 AM in response to Kyle Gilman

Hi Kyle!

The VX1000 can output video via Firewire that can be captured with a Mac, but the camera can't input a Firewire signal. This limitation can be bypassed with a software hack - which I haven't done jet.

I don't want to use the camera(and the cameras powersupply), because its not in best condition and it could be harmed by running for 10 or more hours (it gets quite hot even after one hour, and in this room its around 30 degrees in the shade at the moment).

I know that a video card with s-video out is not the best option, but its cheaper than a professional video out card and I need it primarily to the colours in the taget colour space (TV gamma). To controll the picture quality/details I will just use my computer monitor.

But that is all off topic! I captured some footage via Firewire and the 8 left/right most pixels are black - thats a fact.

This is probably a VX1000 specific problem. I just need to know if the image is cut or squashed from 720 to 704 pixels.

Cheers

Balrock

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