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January 14th, 2013, 02:25 PM
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#46 |
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Inner Circle
Join Date: Jun 2003
Location: San Jose, CA
Posts: 2,222
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
We shouldn't expect video quality of 1080p60 @ 35 Mbits/second to be much better than 1080p30 @ ~16 MBits/second. Sony (and, later, Convergent Design) has been shipping its MPEG2 compression codec since early 2008 in a unit that offers 1080p -> 720p downsizing. What's up with the hesitation to offer 1080p60 machines with 70 - 100 Mbps MPEG2 basic internal recording in any of its models ?
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January 15th, 2013, 06:02 AM
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#47 |
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Join Date: Dec 2010
Location: Western Australia
Posts: 576
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
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January 16th, 2013, 11:14 AM
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#48 | |
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Inner Circle
Join Date: Jan 2006
Posts: 2,699
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Quote:
The reason is that there is more inter-frame redundancy for the compressor to take advantage of. Typically, the GOP period would remain the same, with the GOP length doubling. (So if for 30p I frames were every 1/2 second, with a GOP length (number of difference frames) of 15, for 60p you'd keep an I frame every 1/2 second, but increase the GOP length to 30.) Since the size of I frames is far higher than difference frames, it should be obvious that doubling the progressive framerate doesn't need anything like twice the bitrate to remain quality. |
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January 16th, 2013, 07:20 PM
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#49 |
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Inner Circle
Join Date: Jun 2003
Location: San Jose, CA
Posts: 2,222
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Possibly. 720p60 and 1080p30 are allocated the same bitrates in every system I know. From the perspective of doubling the spacial data from 1280x720 to 1920x1080, a doubling of the bitrate used at 720p60 to represent 1080p60 is sensible. The I-Frame would need to represent twice as much spacial data and so would every intermediate frame. But I can see your point if you think that the data rate used for 720p60 is too high.
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January 19th, 2013, 12:09 PM
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#50 |
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Tourist
Join Date: May 2011
Location: new york
Posts: 3
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Hi guys, by any chance, do you know the dimension of the GC-PX100 in mm ? Height, Width, Depth in comparison to the Canon HF G20 ? Thank you
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March 3rd, 2013, 05:05 PM
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#51 |
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Major Player
Join Date: Mar 2011
Location: London, UK
Posts: 353
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Saw this camera at 'Focus On Imaging' (NEC, UK) today. Interesting shape and spec. The guy guarding it didn't know much about issues when downsizing to HD from a high res stills sensor and unfortunately, there was no monitor connected to make a judgement.
The shape is different and it is not too heavy. The camera had a short mic. connected to the 3.5mm jack but that wasn't included in the price. I would like to see the dof of the 1:1/2.3 sensor (ridiculous way of specifying it!) at F1.2. If it could give a usefully shallow dof, this could be a compact entry level camera with some creative film-like characteristics and none of the crippling SLR handling issues. |
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March 19th, 2013, 11:02 AM
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#52 |
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Major Player
Join Date: Aug 2002
Location: Whidbey Is, WA
Posts: 326
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
B&H does have this in their specs.
High Definition AVCHD 1920 x 1080p / 60 fps (36Mbps) 1280 x 720p / 120 fps
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www.breathedeepproductions.com |
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March 19th, 2013, 11:03 AM
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#53 |
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Obstreperous Rex
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
720p120 ain't too bad... ;-)
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April 14th, 2013, 12:57 PM
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#54 |
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Trustee
Join Date: Jan 2002
Location: Pembroke Pines, Florida
Posts: 1,418
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Just picked up the only one B&H had in store stock (NY Superstore).....initial test footage shows TREMENDOUS chromatic aberration and highlight clipping.....not impressed.....this might go back- I hate CA and clipped highlights.......every JVC I've had always has these 2 issues.
Tested using .mov format at 60 fps.......my Mac is reporting data rates of over 39 mbps which is higher than JVC is claiming.....JVC should allow 30 and 24 fps options- why limit to just 60....lower frame rates at 35mbps should allow for higher quality video! The video is sharp however but the CA and clipping ruins it! Last edited by Steve Nunez; April 14th, 2013 at 03:43 PM. |
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April 16th, 2013, 04:27 PM
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#55 |
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Trustee
Join Date: Jan 2002
Location: Pembroke Pines, Florida
Posts: 1,418
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Re: Procision JVC GC-PX100 Camcorder announced at CES2013
Returned the JVC- I couldn't accept the chromatic aberrations and clipping- at $999 I couldn't justify it.....for a mere $300 more I could get another GH3!
JVC really has to do something about putting out cameras like this- I have yet to be impressed by one of their cameras despite having owned a few prosumer models- they get an A+ for innovative cameras but the quality is just often too lackluster. (Note: The AF didn't seem to work at 600 fps which was very smeared looking and very low res.....at higher frame rates the AF did seem to work.) |
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