Dvcpro hd codec problems... Help!

H

HVXSHROPSHIRE

Member
Hi,

This is my situation: I am using FCP 6.0.4 and using the DVCPRO HD codecs when editing with my HVX200a footage. I realized recently that the capturing resolution of 720/24p is 1280x720. But the Codec resolution of the sequence preset for 720/24p is 960x720. It does the same thing with 1080/30p the capturing resolution is 1920x1080 and the sequence preset for DVCPRO HD for 1080/30p is 1280x1080?

Why do the panasonic sequence presets downgrade my resolution from what I capture in on the HVX200a. I have tried making edited copies of the codecs and using them for my sequence preset but no matter what in my capture scratch window my clips read as downgraded resolution files compared to what I shot them with on camera. Can anyone help me with this, has anyone figured out an answer for this. I am capturing at the same resolution as the EX1 but my sequence presets are always lower resolution unlike the Sony XD camera codecs in FCP 6.0.4....

help.
 
They aren't downgrading anything. 960x720 and 1280x1080 are the actual sizes of what DVCPro HD captures.

There is nothing wrong. This is what the HVX records.
 
Well the sensors on the camera are actually only 960x540 (compared to 1440x1080 on most HDV cameras). They do some electronic juggling called "Pixel Shifting" to get the image to 1920x1080, then feed that to the onboard software. Then it gets converted to DVCProHD. That conversion at the codec level changes 1920x1080 to 1280x1080 to fit inside that 100 mbps stream.

So with the HVX you have a couple of things to point at:

1. The sensors are 960x540
2. The codec only records 1280x1080 or 960x720


However at no point is the HVX actually capturing 1920x1080. So it can't be "restored" with Cineform, or anything else. The new HPX170 has the same issue though with the HD-SDI port, it can avoid the downgrade from the DVCProHD codec.

Sorry, it's just the nature of the camera.
 
PerroneFord said:
So with the HVX you have a couple of things to point at:

1. The sensors are 960x540
Click to expand...

You discount the spatial offset which equates to a 1.1m imager. Bad idea, it shortchanges what the camera is capable of doing.


2. The codec only records 1280x1080 or 960x720
This is do to a pre-filter applied prior to compression, and nothing to do with the what comes out of the HD-SDI in playback.

However at no point is the HVX actually capturing 1920x1080.
Click to expand...

Well in a way you are wrong, at the camera end of things the capture to the DSP is very definitely 1920X10 and durin the entire camera processit is in the native format of the DSP capture.

So it can't be "restored" with Cineform, or anything else. The new HPX170 has the same issue though with the HD-SDI port, it can avoid the downgrade from the DVCProHD codec.
Click to expand...

Again you are wrong. If you capture at the HD-SDI output it is 1920X1080, it has not seen the pre-filter.
 
Jan_Crittenden said:
You discount the spatial offset which equates to a 1.1m imager. Bad idea, it shortchanges what the camera is capable of doing.
Click to expand...

No, I didn't discount it.

Jan_Crittenden said:
Well in a way you are wrong, at the camera end of things the capture to the DSP is very definitely 1920X10 and durin the entire camera processit is in the native format of the DSP capture.
Click to expand...

Yes, it is 1920x1080 after the pixel shift. Which is what I alluded to. When this happens in the chain does not preclude the fact that it does happen in the chain.

Jan_Crittenden said:
Again you are wrong. If you capture at the HD-SDI output it is 1920X1080, it has not seen the pre-filter.
Click to expand...

How does he capture at the HD-SDI port from his HVX200a?
 
PerroneFord said:
No, I didn't discount it.
Yes, it is 1920x1080 after the pixel shift. Which is what I alluded to. When this happens in the chain does not preclude the fact that it does happen in the chain.
Click to expand...

Well yes you did discount it, when you said "However at no point is the HVX actually capturing 1920x1080"

The fact is that the spatial offset does give the HVX a 1.1 million effective resoultion. This is captured into the DSP at 1080 X 1920. And your point seemed to allude to the fact that this was not even possible. If it wasn't possible then the HVX would be basically a very good SD camera, but that is not true, it is a very good HD camera.

PerroneFord said:
How does he capture at the HD-SDI port from his HVX200a?
Click to expand...

Use an AJA compnent to SDI conversion, we do it all the time.

to add to this discussion, the footprint of the codec is due to the prefilter that takes place prior to compresssion. This prefilter resolves frequencies that just are problematic for the codec and would be unpleasant artifacts. After the prefilter is the compression. This means that when we talk about the compression ratio, in DVCPRO HD it is 6.7 to 1. If we didn't prefilter it h=would have a more harsh 10:1. Keep in mind that HD at 8Bits is 994Mbs, if there is no prefilter you would have a 1920 X 1080 or a 1280 X 720 footprint. The full foot print allows for a an easy calculation of the compression ratio. To date the only codec I have see that does a really good job of this is AVC-Intra.

Hope that helps,

Jan
 
Ok, you kind of lost me Jan. So is there a way to keep my footage at 1920 x 1080 or 1280 x 720 when bringing in my footage into FCP? I am about to film a short for Miami Film fest and want to use my HVX200a for production instead of a buddy's ex1 because I like the "more organic" artsy look of the hvx. But at the end resolution will be the deciding factor for what to chose because adventually I want to bring it to 35.

If you say there is a way to keep my resolution as high as possible, please tell me the steps to go about doing so.


Thank you!

Jay Shropshire (student)
 
HVXSHROPSHIRE said:
Ok, you kind of lost me Jan. So is there a way to keep my footage at 1920 x 1080 or 1280 x 720 when bringing in my footage into FCP? I am about to film a short for Miami Film fest and want to use my HVX200a for production instead of a buddy's ex1 because I like the "more organic" artsy look of the hvx. But at the end resolution will be the deciding factor for what to chose because adventually I want to bring it to 35.

If you say there is a way to keep my resolution as high as possible, please tell me the steps to go about doing so.
Click to expand...

Hi, do not worry about the footprint of the footage, it is part of the compression scheme. When you go to play it back it will be the right size coming out of the HD-SDI port. By trying to resize it on the timeline you are just causing unwanted artificats. Use the easy setup for the DVCPRO HD format you are wanting and just leave it there, this will net you the best results.

Best,

Jan
 
You are looking at the "compressed" footprint and trying to make it an uncompressed footprint. Use the easy setups, it will be fine.

Jan
 
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