Convergent Design

Kholi said:
So while I'm daydreaming here about the nanoFlash and 170 combination I'm gonna post up some thoughts. Namely on the HPX170 image in regards to DVCproHD and Sony's I-Frame and Long-GOP MPEG2 codec being used by convergent to deliver media from High-Speed CF Cards.


The questions I'll have to answer for myself immediately when the HPX170 comes out (might even have to just use an HPX500 in the interim to test) are:

1) How does DVCproHD compare to SONY's 4:2:2 codec @ various bitrates and between Long-GOP and I-Frame?

2) What's the resolution increase "look like" when it's all said and done? The numbers say nice things, but does it "look" that much better?

3) What kind of package do you end up with as far as media and recording? 4 CF Cards and 3 P2 Cards for ultimate versatility? Or do you migrate completely to CF cards in an abundant number equivalent to the cost of P2 Cards and simply use your package as a "modified" Panasonic HPX170, the best with even BETTER benefits than before?

September's so far off, can't wait for these two products to hit!

Also, I hope that Convergent will put up a sheet on the nanoFlash outlining the specifics of the unit. That way I can stare at it once a day.
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Hi Kholi-
WOW, what a post! We'll get the nanoFlash Specs up on the website this week. We have the circuit schematics almost complete and are working on the box design.

Regarding the comparison of Sony MPEG2 I-Frame / Long-GOP vs DVCProHD, our tests indicate that the 50 Mbps Long-GOP outperforms DVCProHD in still image resolution tests. As you noted, the MPEG2 CODEC compresses at the full 1920x1080 raster. Also Long-GOP allocates significantly more bits to the I-Frame, than does DVCProHD. That's because the P and B frames (which make up most of the datastream) are typically 50% and 25% (respectively) the size of an I-Frame. MPEG2 Long-GOP is simply a more sophisticated compression algorithm and can make better use of the available bitrate.

Long-GOP MPEG2 is more difficult to edit, but as processor performance has steadily improved, Long-GOP editing has become much more acceptable.

I think the combination of several P2 cards (for backup and material review) combined with a stack of low-cost Compact Flash cards is probably ideal. One hour's worth of P2 cards (at 100 Mbps) will run you around $2700, while the equivalent in CF cards (at 50 Mbps) will only cost $150.

Mike Schell
Convergent Design
 
Mike Schell said:
Regarding the comparison of Sony MPEG2 I-Frame / Long-GOP vs DVCProHD, our tests indicate that the 50 Mbps Long-GOP outperforms DVCProHD in still image resolution tests.
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Hey Mike, can you run some motion tests though? Still tests are pointless since we're talking about recording moving images.

MPEG2 Long-GOP is simply a more sophisticated compression algorithm and can make better use of the available bitrate.
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For stills, yes. But we're not shooting stills. And in motion, that's where Long-GOP can fall to complete crap if the bitrate is too low. 50mbps is probably enough to avoid that, 100mbps would definitely be enough. But again, comparison of stills is pointless as we're not using these cameras to shoot stills.
 
Hi Barry-
We will be posting some full motion video as soon as we get our FAT table implementation complete, which should be debugged later this week. I agree that full-motion video is the best comparison.
From a media cost point of view, you can economically shoot at even 100 Mbps Long-GOP using CF cards, which should look fantastic.

I'll post some comparison video ASAP.

Mike
 
Mike Schell said:
Hi Kholi-
WOW, what a post! We'll get the nanoFlash Specs up on the website this week. We have the circuit schematics almost complete and are working on the box design.

Regarding the comparison of Sony MPEG2 I-Frame / Long-GOP vs DVCProHD, our tests indicate that the 50 Mbps Long-GOP outperforms DVCProHD in still image resolution tests. As you noted, the MPEG2 CODEC compresses at the full 1920x1080 raster. Also Long-GOP allocates significantly more bits to the I-Frame, than does DVCProHD. That's because the P and B frames (which make up most of the datastream) are typically 50% and 25% (respectively) the size of an I-Frame. MPEG2 Long-GOP is simply a more sophisticated compression algorithm and can make better use of the available bitrate.

Long-GOP MPEG2 is more difficult to edit, but as processor performance has steadily improved, Long-GOP editing has become much more acceptable.

I think the combination of several P2 cards (for backup and material review) combined with a stack of low-cost Compact Flash cards is probably ideal. One hour's worth of P2 cards (at 100 Mbps) will run you around $2700, while the equivalent in CF cards (at 50 Mbps) will only cost $150.

Mike Schell
Convergent Design
Click to expand...

:B I'm just'a dreamin' as usual.

Naturally I'm with Barry in sayin' let's get some video up, but you're already workin' on that so great.

I won't hold you to it, but I am going to ask: is your preference the SONY Long-GOP flavor or the SONY I-Frame flavor and if so is it because the Long-GOP flavor @ 50mbps is just as good as the I-Frame at a higher bitrate?

I've been assuming that I'd merely go straight for the throat and use the I-Frame at 100 or 160 if the I-Frame, unlike DVCproHD, is a Full Raster Codec.

It'll be really hard for me to keep my P2 Media if the post workflow with the SONY I-Frame codec is just as easy. I'll constantly be spurned to get rid of them in favor of putting some cash back in my pocket! Then again, might have to keep em for backup anyway.

Choices choices.
 
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