I'm shooting on the HVX and I wanted to shoot in 1080 instead of 720 because of the color space and compression size advantages and slight resolution increase. I was wondering though if there's any difference in the gamma, color quality, or image characteristics of 1080 footage from the HVX as opposed to 720. How do I get the best quality out of 1080 footage?
Shooting in 1080p
- Thread starter FatBird19
- Start date
John Froton
Well-known member
I don't believe there would be any difference in gamma, color quality or image characteristics other than the benefit of those characteristics being compressed more efficiently under 1080 as opposed to 720.
To get the best quality after the footage has been shot, make sure to do any compositing, gamma changes, color correction, special effects ...etc, in uncompressed space if possible, before rendering out to whatever final codec you will be delivering to. However, if you are doing simple cuts without processing, you could just render out to your delivery codec.
To get the best quality after the footage has been shot, make sure to do any compositing, gamma changes, color correction, special effects ...etc, in uncompressed space if possible, before rendering out to whatever final codec you will be delivering to. However, if you are doing simple cuts without processing, you could just render out to your delivery codec.
I've always wanted to know why people do this. If the footage has already been affected by a compression codec, then what does it matter if I tweak the footage within that codec or uncompressed? Something that I've always wondered.
The color space for DVCPRO HD is the same in 720 or 1080 -- 4:2:2.
John Froton
Well-known member
well the DVCPro HD codec has a fairly high compression ratio, and while there is nothing you can do (technically there is but) to avoid the initial compressing that takes place when the camcorder shoots and encodes the footage, you do want to try and avoid compressing to DVCPro HD again if possible.
When you lay out a DVCPro HD clip on an NLE timeline and make changes to the footage, or add titles or whatever, you will get a better looking end result if you encode (render) with a less lossy codec than with a more lossy codec. DVCPro HD is a fairly lossy codec with better than average color space in comparison to most other available codecs.
Think of it this way, if the HVX could record in a very high quality, nearly lossless format, it would take up many more times the space than it does with DVCPro HD. If we render using uncompressed or a nearly lossless codec on the computer, then we go a long way toward making sure that the image does not degrade further to a considerable degree as we recompress it.
The bottom line, However, is to consider what the final delivery format needs to be. If it is going to be downsized for DVD or the web, then there is no harm in just compositing layers and titles and just exporting to the final product. If you are producing HD content for theatrical screening and want to preserve the highest quality possible through and through, then you shoud consider building and rendering your footage in as lossless a manner as you can afford. If you can manage to export work out as uncompressed video, when the time comes to compress for delivery, you will have maintained the best quality possible.
When you lay out a DVCPro HD clip on an NLE timeline and make changes to the footage, or add titles or whatever, you will get a better looking end result if you encode (render) with a less lossy codec than with a more lossy codec. DVCPro HD is a fairly lossy codec with better than average color space in comparison to most other available codecs.
Think of it this way, if the HVX could record in a very high quality, nearly lossless format, it would take up many more times the space than it does with DVCPro HD. If we render using uncompressed or a nearly lossless codec on the computer, then we go a long way toward making sure that the image does not degrade further to a considerable degree as we recompress it.
The bottom line, However, is to consider what the final delivery format needs to be. If it is going to be downsized for DVD or the web, then there is no harm in just compositing layers and titles and just exporting to the final product. If you are producing HD content for theatrical screening and want to preserve the highest quality possible through and through, then you shoud consider building and rendering your footage in as lossless a manner as you can afford. If you can manage to export work out as uncompressed video, when the time comes to compress for delivery, you will have maintained the best quality possible.
John Froton
Well-known member
Because of this fact, I too would have thought that 1080 and 720 would compress equally. But apparently Barry Green and others have noted that, because of the larger space available in 1080, the compression becomes more efficient.
Yet another reason that Barry recommends shooting in 1080p if you can, rather than 720p, if your looking for better quality results from the compression.
Barry_Green
Moderator
1080 is more efficient and less compressed on an HVX200, yes. On an HPX2000, maybe not.
The difference is that the HVX200 can only create a frame that has about 1440 x 810 worth of detail; it can't truly resolve a full 1920x1080. So if you pack 1440 x 810 into a 1280x1080 frame, you end up with a codec frame that's about 25% under-utilized. So DVCPRO-HD takes that underutilized space and spreads out the compression more mildly across the frame, resulting in visibly less compressed footage when in 1080 mode.
There will be less of an advantage in an HPX500, and I'd guess that by the time you get to an HPX2000 the advantage is probably gone and 1080 will be about as visibly compressed as 720 is.
The difference is that the HVX200 can only create a frame that has about 1440 x 810 worth of detail; it can't truly resolve a full 1920x1080. So if you pack 1440 x 810 into a 1280x1080 frame, you end up with a codec frame that's about 25% under-utilized. So DVCPRO-HD takes that underutilized space and spreads out the compression more mildly across the frame, resulting in visibly less compressed footage when in 1080 mode.
There will be less of an advantage in an HPX500, and I'd guess that by the time you get to an HPX2000 the advantage is probably gone and 1080 will be about as visibly compressed as 720 is.
That's not actually the color space -- that is the color sampling.
The color space is the same (ITU 709) for both DVCProHD resolutions as well, but it is worth noting that this is not the same as SD, which uses ITU 601. In order to maintain the colors correctly in your workflow, you may need to apply filters to convert from one color space to another.
rogar-BigGrin(DBG)Since the HVX's 3 chips are only 540x960, that's the maximum chroma resolution there can be per channel. Storing that footage at 1080x1280 in 4:2:2 gives you a color sampling of about 4:2.6:2.6, if such a sampling standard existed.
John Froton
Well-known member
If you shoot 1080i 24pA or 30pA, then the 24 or 30 progressive video is embodied in an interlaced wrapper (codec). All you have to do to extract the progressive video is to put the footage into an appropriate progressive timeline in your NLE and export as progressive. The NLE will reassemble the footage as progressive and remove the duplicate frames.
After that you are left with true, full resolution 1080p video.
After that you are left with true, full resolution 1080p video.
You're right; my mistake.
i dont have a HVX in front of me (and i usually shoot 720p), but isnt there a 1080i 24pN setting when using P2 cards (as opposed to a Firestore which is only 24p over 60i)?
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John Froton
Well-known member
No, the PN mode only works for 720p because the DVCPro HD codec does not support progressive encoding at 1080, only at 720.