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Adam White
Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 2:00:46 am

Hello experts,

I'm preparing an independent feature for HD DVD encoding.

I've been given a DVC Pro HD 1080i file to transcode. I've done some tests, using the H.264 codec in compressor, but whatever the settings I've tried the file that comes out is stretched and distorted with completely the wrong aspect ratio.

In the geometry tab, the pixel aspect reads as 0.6667 - DVC Pro HD 1080i60.

I know the file was exported from FCP v6, and I'm aware of a bug with this version of the software and the DVC Pro HD codec (as outlined here; http://lafcpug.org/Tutorials/basic_dvcpro_bug.html)

When played in QuickTime, the DVC Pro HD file looks fine with correct ratio. However, in the Mac viewer window gives the dimensions of the file as 302 x 254. Clearly not correct.

Is there any kind of work around for this or is the file I've been given simply unworkable? I need to transcode it for SD and HD (H.264) DVD's.

Hope someone can assist in some way - I've never come across this before and am frankly a little perplexed!

Best,
Adam













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David Roth Weiss
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 2:07:06 am

I don't know why you're having the problem, but I would hazard a guess that you could fix it in the geometry window by simply checking custom, and entering 1920x1080.

David Roth Weiss
Director/Editor/Colorist
David Weiss Productions, Inc.
Los Angeles

POST-PRODUCTION WITHOUT THE USUAL INSANITY ™


A forum host of Creative COW's Apple Final Cut Pro, Business & Marketing, Indie Film & Documentary, and Film History & Appreciations forums.


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 2:22:33 am

Hi David, thanks for your response.

The dimensions (encoded pixels) section of the geometry tab is grayed out and locked to "Automatic" and cannot be altered, which is another oddity! If I change the output image inset (padding) to "16:9 1.78:1" then the resulting video has the correct ratio, but is pillar-boxed on either side of the image.


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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 2:28:19 am

And what are you doing exporting something for the web in HD (DVCProHD) pixels?
Everything for the web MUST be Square pixels.

ADAM, to make any 16x9 clip for the web, you must make sure that the sides (high/wide) keeps always this 16 to 9 proportion. So you can only use values like:
- 160 x 90
- 240 x 135
- 320 x 180
- 480 x 270..etc
If you export with QT, you will always get Square Pixels (as you need).
But if you use Compressor, be careful and check "Square pixels".
If you just let "Pixels: Default for size" you can get some funny distortion on play.
Cheers,
rafael




http://www.nagavideo.com


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 2:43:00 am

Hi Rafael. Thanks for your input.

This compression is not for a clip to go online. I'm compressing a H.264 file for HD DVD. I can't seem to adjust any of the Dimensions settings in the Geometry tab because they are all locked, so I can't change the aspect ratio to "Square pixels".


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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 3:10:20 am

Hi Adam,
Right. That's correct. You have the "Pixels options" grayed, because for HD-DVD and Bluray, can not be options: They can only be Squared pixels.
Can you open the DVCProHD clip in QT Player and tell us what exactly says the Info Window?
And one question:
When you have imported your DVCProHD clip to Compressor, in "Video Format" have you properly identified the clip as 1440x1080?
rafael

http://www.nagavideo.com


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 3:41:08 am

The info from QuickTime Player;
Format: DVCProHD1080i60, 1280 x 1080 (1888 x 1062), Millions.
FPS: 29.97
Data Size: 64.39GB
Data Rate: 116.64mbit/s

When importing the clip into Compressor, Video info appears as;
Econded Bounds: 1280x1080
Display bounds: 1920x1080
Pixel Aspect Ratio: DVCProHD 1080i (16:9)
Frame rate: 29.97

I have just done some tests converting the file for an NTSC SD DVD (my client needs standard definition copies too) and it works fine - the aspect ratio is correct. So it must be an H.264 setting that I haven't got right. Any thoughts?


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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 6:12:34 am

Adam,
What I want to know is the Info of the H264 that you get on exporting from Compressor.
Open the file in QT, and "Comm-I".
Some where the Pixels aspect have been misinterpreted, and I think that when importing the DVCProHD file to Compressor.
Did you used a Compressor Preset?
rafael


http://www.nagavideo.com


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 13, 2009 at 4:08:57 pm

Hi Rafael, sorry I misunderstood your question.

The info from a test H.264 clip that I compressed is as follows;
Format: H.264, 1920 x 1080, Millions
FPS: 29.97

Yes, I used a preset from Compressor - namely HD DVD: H.264 90 Minutes. Then I just adjusted the bitrate accordingly to suit my requirements and set Video Format from 'Automatic' to '1920 x 1080'. I tried adjusting some of the geometry settings after I got exports with the wrong ratio, but none of these changes worked.

I'm sure I must be making a basic error somewhere along the way, maybe you can help?

Adam





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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 14, 2009 at 2:18:37 am

Hi Adam,
Thinking and thinking, but no idea.
Size and Pixels aspects shouldn't be an issue:
Try letting "Video Format: Automatic".
What I would do is to avoid the HD-DVD Preset, and try to do a H264 with these specs.
I'm lost,
rafael


http://www.nagavideo.com


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Michael Gissing
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 14, 2009 at 3:24:01 am

"When importing the clip into Compressor, Video info appears as;
Econded Bounds: 1280x1080
Display bounds: 1920x1080
Pixel Aspect Ratio: DVCProHD 1080i (16:9)
Frame rate: 29.97 "

Strange numbers. Anamorphic 16:9 is 1440 x 1080. True 16:9 is 1920 x 1080 but 1280 x 1080 is weird.


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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 15, 2009 at 5:00:44 am

[Michael Gissing] "Strange numbers. Anamorphic 16:9 is 1440 x 1080. True 16:9 is 1920 x 1080 but 1280 x 1080 is weird."
You are right Michael. I haven't realized that.
The size is not standard at all.
rafael


http://www.nagavideo.com


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 16, 2009 at 3:39:00 am

Hey Guys,

Thanks for your input on this.

I carried on plugging away on this today - and discovered that in fact the encoded files DO have the correct aspect ratio. BUT, it was QuickTime Player displaying them incorrectly! If I open the files in any other programme (i.e. VLC, MpegStreamclip) they look fine.

So the files were being encoded correctly, but QuickTime Player was stretching them on playback. I'm calling Apple later on today to get this mess sorted out!

Oh, by the way, as for the 1280 x 1080 resolution, it's the correct dimensions for the DVC Pro HD codec. DVC Pro isn't technically TRUE HD as we know it, so it downsamples higher resolutions to give you 1280 x 1080. Just to add it another complexity, these weird dimensions only apply to 60i DVC Pro video, where as anything in 50i has the much more sensible (and familiar!) dimensions of 1440 x 1080.

Thanks again for trying to help out!

Best,
Adam




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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 17, 2009 at 3:47:40 pm

[Adam White] "Oh, by the way, as for the 1280 x 1080 resolution, it's the correct dimensions for the DVC Pro HD codec. DVC Pro isn't technically TRUE HD as we know it, so it downsamples higher resolutions to give you 1280 x 1080. Just to add it another complexity, these weird dimensions only apply to 60i DVC Pro video, where as anything in 50i has the much more sensible (and familiar!) dimensions of 1440 x 1080. "

No Adam.
Full raster HD is 1920x1080 Square pixels.
DVCproHD, XDCAM HD and HDV, use HD Pixels and the size is 1440x1080.
1280x1080 doesn't belong to any standard.
Cheers,
rafael



http://www.nagavideo.com


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 17, 2009 at 4:59:25 pm

Rafael,

From an AJA Whitepaper about the DVC Pro HD format;

"DVCProHD works in non-standard raster sizes, with non-square pixels, to create the same 16:9 picture aspect as full raster HD, without storing as much data. This once again helps to keep the data rates and encoding difficulty down, however the sacrifice is in real resolution. In some cases this will be an acceptable trade off, and in some it will not. Specifically this can cause issues for effects and keying work. In place of standard 1920x1080, DVCProHD encodes 1280x1080 or 1440x1080 depending on the frame rate. In place of 1280x720, DVCProHD encoding down samples to 960x720."
http://www.aja.com/media_folder_web/AJA_whitepaper_DVCProHD_editing.pdf

The film was shot at 29.97fps - so in 60i - thus, the 1280x1080 dimensions. Had it been shot in 50i then the dimensions would have been 1440x1080.

Also, here you can see a list of Panasonic cameras that use the DVC Pro HD format and the resolutions they record in, the highest resolution being 1280 x 1080 (apart from on the HPX3000 and HPX3700) - http://www.negativespaces.com/blog/tables/digital-production-cameras.htm

So 1280 x 1080 does apply - but only to DVC Pro HD 60i content. I guess you could make an argument that because of the slightly lower resolution it's not TECHNICALLY a true HD format as we know it - but that's another issue altogether I suppose!

Best,
Adam


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Rafael Amador
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 19, 2009 at 4:11:11 am

[Adam White] "So 1280 x 1080 does apply - but only to DVC Pro HD 60i content. I guess you could make an argument that because of the slightly lower resolution it's not TECHNICALLY a true HD format as we know it - but that's another issue altogether I suppose! "
No arguments at all.
I had no idea of this size (not existing in PAL) and as I can see in the FC presets, its apply not only to 1080i60, but also to 1080p24 and 1080p30. Something new learnt. I thought that all the "HD Pixels' formats were working at 1440x1080.
Cheers,
rafael



http://www.nagavideo.com


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John Pale
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 18, 2009 at 5:32:38 am

Rafael, you are completely wrong. Adam is correct.

DVCPRO HD is 1280 pixels (for 1080i/59.94) in the NTSC world. Its only 1440 for PAL.


Adam, do not use the HD-DVD presets. They are for HD-DVD...a now defunct format.
Compressor in Final Cut Studio 3 has BluRay templates, which are what should be used if you want to make a HD disc anyone can actually watch.


Quicktime Player, has for a long time had difficulty with anamorphic pixels. This is nothing new. Don't worry about it.


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Adam White
Re: Exported DVC Pro HD file with incorrect aspect ratio when transcoded for HD DVD
on Dec 18, 2009 at 5:33:11 pm

Hi John,

Thanks for your input.

I've never used (and probably never will again) the HD DVD presets. This particular client asked for a HD DVD (specifically NOT BluRay) to be authored. Personally I would never use this format, but in this line of work the client is king! I still don't get enough requests for High Definition DVD content to warrant purchasing a BluRay burner - but I'm sure the time will come.

Equally, I'll try and avoid the DVC Pro codec in the future, too. Maybe it's just because I'd never used it before, but I didn't get on great with it. I'm just so used to Apple ProRes now - solid as a rock and just WORKS with FCP and Compressor. I don't like to use anything different I guess!

Best,
Adam


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