Pentax K-7 DSLR video specs

S

stip

Well-known member
Don't really know where else to put this...

I kept watching the Pentax rumors forum the last weeks according the upcoming Pentax K-7 DSLR with video mode (official presentation may 20th) and a quite trustfull member posted the following today:




Update on video specs from report of photographer handling a K-7

The full report is in the mega thread. As far as video is concerned, I can supplement the following specs and I changed my OP accordingly:

- Quality of a Pentax K-7 corporate demo video at 720p playing back on a PC is "breathtaking". If this demo video is the real quality of the camera, then "it is worth buying for this alone".

- Selection of 3 video modes 640x416, 1280x720, 1536x1024

- HD video at 720p@30fps

- Video frames stored as still image JPGs

(The post-processed demo video is in AVCHD format)

- With current firmware, the camera will not output live video feed through the HDMI port

- AF works in video

- Mono microphone on body

- Microphone jack

- Rumors intensifying: Possible to shoot video through the VF (via (small?) EVF overlay

- LV out over HDMI

Wording in quotes are from the photographer handling a K-7, not mine.




-->

http://www.pentaxforums.com/forums/pentax-news-rumors/58822-quality-k-7-video.html




no real full HD but storing 720p as still images might be interesting and if it's really "breathtaking" at least they'll heat up competition
 
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mjpeg is a series of jpeg stills in an easier to handle container. i don't see what an image sequence could add.

/matt
 
mattsand said:
mjpeg is a series of jpeg stills in an easier to handle container. i don't see what an image sequence could add.

/matt
Click to expand...


Mjpeg at best settings corresponds to low to medium jpg quality
K-7 will record 720p as a burst mode with higher quality single frames
 
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i'm not sure what your numbers mean or if they're even true, but mjpeg at max quality looks amazing, if a camera recorded that it would be awesome and look better than any other lossy video codec commonly used. either way it's still jpeg, the exact same compression, so for a given bitrate the quality is exactly the same.

/matt
 
oh, and there's also pjpeg, which is "true" photo jpeg but still stored in a stream. i still (no pun intended) don't see what using an image sequence per se would bring.
 
Let me make this clear: I'm not trying to be smart :)

It's info I picked up when some guys made tests over at Pentax rumors:



In my post above, I made a very pessimistic size estimate as for the size of a single frame as JPG. So I made an experiment with a "typical" of my photos and studied JPG sizes at various compression qualities (after downsizing (supersampling) and cropping it to 1280 x 720).

The sizes are as follows:
80 kB @ 00/12
84 kB @ 01/12
104 kB @ 02/12
136 kB @ 03/12 *
156 kB @ 04/12
184 kB @ 05/12 **
220 kB @ 06/12
216 kB @ 07/12
276 kB @ 08/12 ***
340 kB @ 09/12
444 kB @ 10/12 ****
624 kB @ 11/12
888 kB @ 12/12
(Photoshop has a quality slider ranging from 0 (worst) to 12 (best); the stars count from 1 to 4 for the defaults of low, medium, high, maximum)

Going with a "3 star quality" (not necessarily the Pentax 3 star quality!), we end up with the following figures:


Data write rate: 8.1 MB/s (65 Mbit/s, 2x of 5Dmkii H.264)
(this is the limit of many 133x SDHC cards, too)

SDHC 4 GB full: 15,000 frames -- 8 min 27 s (*** quality, "high")
SDHC 32 GB full: 120,000 frames -- 1 hour 7 min 32 s (*** quality, "high")
SDHC 32 GB full: 250,000 frames -- 2 hours 17 min 4 s (* quality, "low")




...






I've done a little test converting some HD footage from my video cam. Converting 2 sequences of 1920x1080 60i to 1280x720 30p no sound with MJPEG codec at different quality (75,85,95)

....

 1280x720p footage, size per frame:

Q=95: 115 kB
Q=85: 55 kB
Q=75: 40 kB




...


This is an interesting statistics. Thanks a lot.

Let me quote the figures:
1280x720p footage, size per frame:

Q=95: 115 kB
Q=85: 55 kB
Q=75: 40 kB

If you look up at my little experiment in post #172 http://www.pentaxforums.com/forums/592891-post172.html you'll see that even MJPEG Quality 95 only corresponds to JPG compression quality 2 or 3 of 12 (One star * quality at best).

So, while MJPEG as such is fine, I fear that compression parameters are rather aggressive by default.






I don't have the knowledge to confirm that but to me it seems reasonable that a DSLR in burst mode produces different (higher quality) images than being embedded in MJPEG.
Help me out if I'm completely naive here :(
 
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great just what we need another 30p cam. but if the mjpeg is say 50Mbps CBR and there is full manual control I'm there, I can wait for 24p in post......only **** thing is it only takes pentax k glass.......my poor nikkors!
 
It looks interesting to people with K-mount lenses.
sdim0068_1024_pfc.jpg



sdim0061_1024_pfc.jpg
sdim0085_1024_pfc.jpg
 
Why would you even release a dslr video camera with manual controls and only offer 30p at this point? I just don't understand how the people making this camera could overlook such an essential feature.
 
video out has an NTSC option so it must have PAL so I wouldn't rule out 25p. For all we know this could be the one. soon find out
 
squig said:
video out has an NTSC option so it must have PAL so I wouldn't rule out 25p. For all we know this could be the one. soon find out
Click to expand...

The 5DII (euro version) has a PAL HDMI output option too.... I don't think it pumps out 25p though. In fact i'm not sure what it does, i'll have to test it out.
 
http://www.pentaxforums.com/forums/603675-post290.html

"format *quality* "duration until 4GB full" -> MBit/s data rate / "kByte/image frame"

1536 x 1024p *** 7:23 -> 74.0 / 316
1536 x 1024p ** 10:22 -> 52.7
1536 x 1024p * 14:40 -> 37.2

1280 x 720p *** 9:26 -> 57.9 / 247
1280 x 720p ** 13:19 -> 41.0
1280 x 720p * 18:37 -> 28.4

640 x 416p *** 31:55 -> 17.1 / 73
640 x 416p ** 41:44 -> 13.1
640 x 416p * 60:57 -> 9.0 / 38


74.0 MBit/s or 9.2 MByte/s is twice the data rate of a Canon 5Dmk2, so far industry's best. Quality would be comparable, because of MJPEG vs. H.264."


1536 x 1024 at 316 kByte jpeg.

$1200 at B&H

http://www.bhphotovideo.com/c/product/622079-REG/Pentax__K_7_SLR_Digital_Camera.html#features
 
I did some testing when I got my D90 it averages about 80kb per frame. I did some jpeg compression on some 1280x720 stills and found that 240k is the sweet spot to my eyes. I think the bar has just been raised. Too bad it's only 30p
 
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