1080p/24 vs. 720p/24

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digexpressions

Active member
I'm thinking about shooting my next event in 24p (been using 720/60p). Since the HMC150 can do 24p in both 1080 and 720, I was wondering if there is any reason not to use the higher 1080p. THANKS
 
Other than transcoding time and HDD space I can't think of any reason to shoot 720/24p over 1080/24p.
 
I would say its nice to have 720 as your final output, but record at 1080. Gives you a lot more leeway for framing, cropping and keying without loosing any quality.
 
From what Barry Green has written, there doesn't seem to be much of a difference - shooting 1080p24 and (properly) downscaling to 720p24 vs just shooting 720p24 straight up. If I recall correctly, from what he wrote, there is a slight advantage with the color, shooting 1080p24, but from the (very) blown up samples he posted, I seriously doubt the difference is going to be notable for normal viewing. Mad is right about having some leeway with framing, shooting 1080p24, but do realize that if you crop much before downscaling, you will lose some image detail, since the cam can only really resolve about 600 lines, no matter what format you record. Depending on what you are shooting, and how much you crop, that might or might not be noticeable.
 
Robert M Wright said:
Mad is right about having some leeway with framing, shooting 1080p24, but do realize that if you crop much before downscaling, you will lose some image detail, since the cam can only really resolve about 600 lines...
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True that too... Although I thought it was in the 800's like 860... ?
 
I'd be much more inclined to shoot 1080p for delivering SD. That really does give you a heck of a lot of leeway with framing.
 
Here's a question: how does identical footage shot at 1080p compare to stuff shot at 720P then blown up to 1080P? Wouldn't the difference not be huge since the sensor isn't much higher than 720?
 
Robert M Wright said:
I'd be much more inclined to shoot 1080p for delivering SD. That really does give you a heck of a lot of leeway with framing.
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I guess that if that is something you find yourself doing often, maybe. Personally I can't remember the last time I cropped a video in that way, I just try to get the framing right to begin with.
 
studio1972 said:
I guess that if that is something you find yourself doing often, maybe. Personally I can't remember the last time I cropped a video in that way, I just try to get the framing right to begin with.
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I agree with Stuart that I try to get the framing right and just downsize to SD when required.

Where I differ from Stuart is that I still shoot 1080 whenever possible. While I like his ability to use less HDD space and have fast transcode and render times, the testing I've personally done shows me that 1080 has a discernible difference when looking at fine details and I use this fine detail when up selling clients from people who still use only DV equipment.

There is no right or wrong answer to this, because it depends on other variables that only you can decide on.

Shoot 720 if you want to save time & space when transcoding / rendering.

Shoot 1080 if you want every last detail available from the camera and don't mind the HDD space and render times.

As for downsizing to DV, if you are shooting for delivery ONLY on DV the 720p makes much more sense.
 
1080p does work the encoder a bit harder but I haven't really compared the two side by side to really see by how much. It is a fact however that a higher resolution at the same framerate given the same 21 mbps bitrate will have to work the encoder a bit harder. Now the bitrate is pretty darn good for AVCHD so it could be rare that you would ever notice it but it could be a concern. If you want guaranteed the least amount of compression artifacts I think 720p is still a bit better. Like I said however you may have to try really hard to notice a difference on 99% of video material.
 
Thomas Smet said:
1080p does work the encoder a bit harder but I haven't really compared the two side by side to really see by how much. It is a fact however that a higher resolution at the same framerate given the same 21 mbps bitrate will have to work the encoder a bit harder. Now the bitrate is pretty darn good for AVCHD so it could be rare that you would ever notice it but it could be a concern. If you want guaranteed the least amount of compression artifacts I think 720p is still a bit better. Like I said however you may have to try really hard to notice a difference on 99% of video material.
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I think it's not quite that simple. If you are talking 720 24p vs 1080 24p I think you are correct. But I'm pretty sure that 720 25p and 30p are actually recorded as 50p and 60p respectively (with duplicate frames that the NLE simply ignores) which means that there is no less compression really. There is a practical advantage though, when transcoding to ProRes FCP actually discards the duplicate frames so the resulting Pro Res file is half the size with 25p footage compared to 50p, for example. Personally I shoot in 720 25p and 50p (using 50p in situations where I might want to convert some of the footage to slo mo). Not saying that is the best way to do it, but it works well for me.
 
The OP was asking about 24p which is why I mentioned it. You do bring up a good point about 25p and 30p however for those who would think they would have the same advantage.

Another thing to take into consideration is that 50p and 60p need just as much bandwidth as 1080p 25p or 30p so the strain on the encoder is about the same.
 
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