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720 vs 1080 – best for downconvert
Hello Everyone,
Well, it seems to be finally happening – clients are asking for HD, by Jove! One client in particular is especially concerned about the quality of SD downconvert and someone (an engineer) within their organization is saying that we should go 1080 rather than 720, since the downconvert is superior, since it’s mathimatically less messy (or something like that). Is there any truth to this?I would like to push for 720p, mostly because I really like the Panasonic HDX900 (and its price point). I’m really trying to avoid having the whole process go HDV, since up to now we’ve always maintained a nice broadcast-quality with real cameras (2/3″ chip) with real lenses.
Also, this client will be sharing this video via intranets, and so really wants it progressive (again, for the best sd downconvert and computer viewing). And so – if 1080 really is better for this should I recommend 1080p or would 720p be just as good?
Thanks!
Bob Pierce -
4 Replies
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In my experience there is zero difference between 720 and 1080 for downconversion. However, we only use our AJA Kona boards for real-time downconversion as hardware downconvert beats software downconvert every time.
All the AJA Kona HD boards do downconversion and the Io HD also does downconversion.
Walter Biscardi, Jr.
Biscardi Creative Media
HD and SD Production for Broadcast and Independent Productions.STOP STARING AND START GRADING WITH APPLE COLOR
The new Color Training DVD now available from the Creative Cow! -
[BobP] “One client in particular is especially concerned about the quality of SD downconvert and someone (an engineer) within their organization is saying that we should go 1080 rather than 720, since the downconvert is superior, since it’s mathimatically less messy (or something like that). Is there any truth to this?”
No truth this at all
– look at FOX or ABC/ESPN/Disney SD vs HD broadcasts (since they only broadcast in 720) to see that this is not an issue.“Also, this client will be sharing this video via intranets, and so really wants it progressive (again, for the best sd downconvert and computer viewing). … would 720p be just as good?”
Over the internet 720p is going to offer you the best of both worlds HD quality, Smaller file sizes, compatibility with WMV progressive delivery.
The WMV 1080i to Progressive is often messy, as any interlace to progressive conversion is.
gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows
Inside look at the IoHD -
Bob,
I have to agree wholly with Gary and Walter. There is no difference in 720 or 1080 when talking about down-conversion. Now, I will say that we are using the AJA Kona 3 cards in our systems. I can’t vouch for BlackMagic.
As an aside to your original quandary, have you considered the Sony XDCAM EX camera? It can shoot just about any HD mode, 720 and 1080. And if you have the latest update to FCP, it has the support needed for the new camera.
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Wayne Carey
Schazam Productions
http://www.schazamproductions.com
https://blogs.creativecow.net/waynecarey -
Technically, what he heard is true. 1080->SD is mathematically less complicated. The scaling process just has to throw away one field, making it 540p square pixels – which calculates to 480p non-square. So the vertical scaling is very clean.
If the content is 4:3 (unusual for HD) then the horizontal scaling is even cleaner. It would be scaling 1440 to 720 – exactly 1/2 the resolution.
But as far as real world results you guys are correct. As long as it’s a high quality scaler like a Kona 3, a Teranex, or the downconverter on an SR deck, then 720p will look just as good. That said, when downconverting using a lousy scaler it is better to start with 1080. Perfect example is the Blackmagic cards’ software downconversion. Starting with 720 looks awful. Starting with 1080 looks less awful.
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