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When is the new HD1 replacement
I heard the new HD1 replacement was to be announced around now, but nothing has come up, anybody know anything?
Thanks |
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Radek |
There are a number of cameras that could have been introduced a year or year and half ago, so they have had plenty of time for tweaking. The issue with consumer cameras, is which has the best compromise you can live with, so I am waiting to see what they introduce, even $1000-$1500 in comparison. I am not happy with the interlace stuff on the Sony's.
Look forward to better one chip, maybe even another three chip model. If it comes down to $3.5K Pro Sony Single chip, or $3K 3 chip JVC with uncompressed out, then the choice would be interesting. I have heard reports that the 720p has less movement artifacts than 1080i Sony's. As I am interested in uncompressed out, it doesn't matter so much. Thanks |
Deinterlace 1080i with best software, get half decent 1080p and excellent 720p.
Radek |
Still, on friendly terms with local State PRO JVC distributor. I am not totally in favour of de-interlacing, and have other reasons for avoiding interlace. So, will ultimately come down to competition and capturing possibilities. Of course if everybody converted to digital cinema tomorrow, it would matter even less. Still waiting for hands on testing of the component on all models.
Wayne. |
Radek -"JVC portion of HDV spec includes 720p60 at 19 Mbps, with GOP 6."
Where do you get that info from? I have never seen any info like that. The 480p60 mode of the JVC cams uses a 12GOP, so I don't know how you figure double the rez and half the GOP. Not likely. |
Ken,
Where did you get GOP of 12? I understood JVC's HDV is GOP 6. Resolution is the same at 30p and 60p. Radek |
Had a quick search on this forum and found this thread where David Newman of Cineform outlines the GOP's. I would guess JVC's site also should have info as well. The GOP structure is essentialy the same as double the GOP and double the frames works out to the same GOP-per-second either way.
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Ken,
Just because you double frame rate does not mean you double GOP. I could not find anywhere anything than GOP 6. Radek |
http://www.dvinfo.net/conf/showthrea...ghlight=12+gop
Well Radek, in this case it does ;>) Here is the link I forgot to include. The GOP structure is common knowledge to those familiar with the cam. All of the specs were talked about inside and out when the cam was new and this forum was blazing. |
Ken,
there used to be HDV Organization chart and I'm pretty sure was GOP 6, but I could be wrong. HD1/10 has GOP 12 but only at 480p60; there is no 720p60 on HD1/10. Radek |
"but I could be wrong"
Ya, your wrong. "there is no 720p60 on HD1/10." Common knowledge. Who ever said there was? |
http://www.adamwilt.com/HDV/ HDV uses long-GOP MPEG2 for video, with a 6-frame GOP for 720p and 12 to 15-frame GOP for 1080i.
Sorry, you're wrong and I never said HD1 is 60p. I'm done, hate repeat myself. Radek |
Radek I don't know if it is a language barrier or what, but there seems to be some form of lack of communication here.
I don't know what you are pointing out with your link, but I see no info on the 480p60 mode GOP. I gave you a link already from David Newman of Cineform AspectHD. If anyone knows the specifics of the cam it is him. I don't know why you have adopted the stance that somehow you can not be wrong, but you are. |
Ken, let's just wait when 720p60 camera comes out, we'll know sure then. This is not really that big deal, 12 GPO give somewhat better results, that's all. Thanks for the link though. Radek
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Well, who knows when a 720p60 cam will be out.
"12 GPO give somewhat better results" better than what? |
The longer GOP, the lower compression. Keeping bit rate constant, if GOP is longer, compression is lower and picture better.
Radek |
If the compressor can handle the bit rate, a lower GOP ALWAYS produces a better picture. ALWAYS!
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Sure, but I said at constant bit rate.
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All of the HDV cams use contant bit rate.
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Of course. I ment comparing different systems at same bit rare. At 25 Mbps, GOP 12 will mean less compression and better look than GOP 6.
Radek |
The GOP structure is a form of compression. The longer the GOP the less bandwidth used and the worse the picture. Sometimes Radek I wonder where you get your logic. HDV uses the same compression scheme no matter what the cam, mpeg2ts, so given your variable of 25Mb/s with one cam at 12GOP and one at 6GOP, the 6GOP is going to look superior. Always.
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If you don't believe, ask David Newman or Frederic Haubricht in HDV Editing forum. They already answered before.
Radek |
Please direct me to the thread.
Thanks. |
Ken, Radek is actually correct here. If you keep bit-rates the same the longer GOP will produce less image distortion as there will be more of the efficient B and P frames as compared with the I frame. The issue with long GOP comes if there are dramatric scene changes within a GOP (like filming a closeup on fire) the image may not be able to visually encode all the scene changes introducing visual blocking. The more often the I frame the more quickly the frame can fully reconstruct. So the longer GOP will have the higher quality for most sequences, but if rare situation the short GOP can be better. A simple example why a longer GOP wins : 25Mb/s DV has a GOP of 1, yet the same bitrate with a GOP of 12 has 4.5 times the resolution in 1080i HDV.
On the issue whether the 720p60 is a 12 frame GOP or a 6, no camera supports it yet so I don't know. I would very much favor the 12 frame GOP. |
It is a shame they haven't figured out to switch GOPS for different scenes, or do variable compression for hard disk recording (as Firewire and internal hard disks, and flash, alternatives to tape are taking off). It is a pity that they don't get this message, so we don't have to tell people "great camera but for filming your kids sports games".
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"great camera but for filming your kids sports games". -- Wayne
Funny you should say that -- really this type of footage is where MPEG will have more trouble. MPEG works best for locked down pro shoots, with shollow DOF, and good lighting, the end result will look pretty nice. It is free-form consumer shoot that MPEG stuggles with. :) |
Would the free form consumer shoot be better with a 6 or 12 GOP?
Back to your reply David, why did Sony settle on a 12/15 GOP and not go even higher if that is what it takes to make it better? As well why has JVC stuck with 6GOP on their latest HD100? The largest complaint about HDV stems from fast motion that results in blurring, or complex scenes like choppy water, not holding up. This has never been a complaint of the the 6 GOP cams but is quite a common issue brought up with the Sony cams. 12/15 GOP seems very long for a constant bit rate, single pass compressor. It may have worked out well on the Sony's, but I can't see 12/15 GOP being prefered over 6GOP by any serious film maker, brand preference and camera model aside. |
Longer GOP is alway better for a fixed bit-rate -- just if all hell breaks loose the short GOP will recover quicker (but neither will look good in that situation.) Compare Sony's 60i to JVC's 30p as way to understand long GOP compression is like trying work out DVD playback by putting a disk up against a bright light. The quality of the compression has more to do with interlaced vs progressive and encoder implemention. Sony is having to encode 60 fields of 1440x540 into 25Mb/s (avg 0.53 bits per pixel) and the JVC only 30 frames 1280x720 into 19Mb/s (avg 0.68 bits per pixel). So the Sony camera has to work harder anyway (and it looks better at 12/15 than it would at 6.)
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