Canon Reveals Their Next Pro Video Cam

[Perrone Ford]

Originally Posted by Robert M Wright

How much sense does it really make for Sony to stick with MPEG-2 much longer though? After a few more new CPU generations (think CPUs with a dozen or more cores that are at least twice as efficient as i7 per core), MPEG-2 just won't offer much comparative advantage for editing purposes, but does suck up significantly more bandwidth (and space). In a few short years things might flip things around a bit, since HDD speeds aren't getting faster nearly as quickly as CPU power - with the lower bandwidth of AVC (faster HDD reads and writes) providing for an overall performance advantage once CPUs can handle AVC as easy as melting butter on a hot griddle.

Agreed. But we aren't there yet. And for right now, the XDCam codec is able to be edited natively for those people who need to do that for speed purposes. When we get to the i9 or i11 or whatever, and AVCHD presents no significant burden for editing then it might be prudent to move along.

But at this point, there's no compelling reason to leave the current codec. It meets broadcast spec, it's easy to edit, and it looks pretty darn good at higher bitrates. I sincerely hope the next jump is to wavelet and not AVC based.

[Steve Phillipps]

EX codec doesn't meet EBU broadcast specs, needs to 50 mb/s.
Steve

[Robert M Wright]

Originally Posted by Perrone Ford

I sincerely hope the next jump is to wavelet and not AVC based.

I don't know why wavelet compression has been so largely ignored. It must have to do with money interests, since the technology pretty much makes more sense fundamentally (and has for awhile). I sometimes wonder why Panasonic didn't just buy out Cineform, and use that codec instead of introducing AVC-I. They could have got much faster adoption, simply because it isn't as taxing on current day CPUs (if for no other reason).

[Simon Wyndham]

I don't know why wavelet compression has been so largely ignored.

Could be down to processing power (and hence power draw) of doing it realtime. Remember the Grass Valley Infinity? Recorded JPEG2000 and drew an absolutely huge amount of power.

[Simon Wyndham]

EX codec doesn't meet EBU broadcast specs, needs to 50 mb/s.

Well, the EBU recommendations. Remember they aren't hard and fast specifications. Just recommendations.

[Robert M Wright]

Originally Posted by Simon Wyndham

Could be down to processing power (and hence power draw) of doing it realtime. Remember the Grass Valley Infinity? Recorded JPEG2000 and drew an absolutely huge amount of power.

A modern quad core CPU can do encoding with Cineform's codec in real time a whale of a lot easier than H264. If a general purpose CPU can do it pretty easily, should be no problem whatsoever to create a dedicated encoder chip specifically designed for it.

[Steve Phillipps]

Originally Posted by Simon Wyndham

Well, the EBU recommendations. Remember they aren't hard and fast specifications. Just recommendations.

But they do tend to be valued by broadcasters.
Steve

[David Heath]

Originally Posted by Robert M Wright

It's not AVC-I that would make so much a difference, as putting in the full raster imaging chips. The HPX170 just doesn't use imaging chips that even come close to offering the resolution of the imaging chips in EX camcorders, ...

The HPX170 chipset is well past it's sell by date, and now 1920x1080 displays and codecs are common that's becoming increasingly obvious.

I feel 1 megapixel may be the best compromise for 1/3" chips - twice the number of photosites as the HPX170, but without compromising individual photosite size too severely. But best of all are obviously full 2 megapixel (1920x1080) on a 1/2" chip. Regrettably only Sony seems to offer that in a prosumer grade camera.

..and Panasonic's AVCCAM AVCHD H264 encoding is apparently as good or better (image fidelity wise), compared to XDCAM EX MPEG-2 encoding from the EX cams.

I disagree - it depends what criteria you use. Is your test one with a lot of motion or a lot of fine detail and sharp edges? Current implementations of AVC-HD by Panasonic seem to cope well with motion, but much less so with mosquito noise, especially in 1080i mode. (There are many reports arguing that for the HMC150 it's best to use 720p rather than 1080 - 720 mode captures all the detail the chips are capable of producing, whilst stressing the codec less.)

And the mosquito noise can be argued to be more objectionable than codec failings due to motion - it's there all the time, often "twinkling" around the edges of static detail.

The ratio of I frames to difference frames in a codec is not fixed, it's easy to see how static performance can be traded off for better motion performance. With AVCCAM they seem to weight in favour of motion.

What is really needed for the prosumer is a camera styled like JVCs HM700, but 1/2", full 1920x1080 chips, and a codec to the standard of XDCAM 50Mbs or AVC-Intra 100. And ideally recording to both "full spec" media (P2 or SxS) AND consumer memory like SDHC or CF. There is no technical reason why that is not possible.

Nothing currently meets all the criteria. Of what's available, I'd argue the EX is the obvious first choice at the moment, since at least you can get it to meet those criteria with an external recorder.

[Robert M Wright]

Perhaps you are looking at Panasonic's consumer AVCHD? Apparently the pro cameras get a much better AVCHD encoder (branded as AVCCAM) than the consumer camcorders (or the GH1, for that matter). Barry Green did a very direct comparison of AVCCAM AVCHD (the branded AVCHD for the pro cams), by attaching an AG-HMR10 to an EX1, recording XDCAM EX in-camera and Panasonic's AVCCAM AVCHD with the AG-HMR10 (recording from exactly the same source coming off the imaging block - true apples to apples comparison). In the article he wrote, he showed comparison frame grabs, where the codecs were stressed, and the AVC looked a tad better on the whole. He didn't post frame grabs of the more typical ("unstressed") footage, but did state that both codecs produced very good images that were quite comparable in most of the footage. When I look at blown up images shot with my HMC40 (full raster chips), it looks awfully good (just a whale of a lot better than HDV) and does seem (to me) somewhat difficult to imagine XDCAM EX encoding being a whole bunch better at maintaining image fidelity from the imaging block. I don't shoot 1080i though.

[Robert M Wright]

I'd love to see a similar (apples to apples) test (XDCAM EX vs AVCCAM with an EX1 or EX3) panning a res chart slowly.

[David Heath]

Originally Posted by Robert M Wright

Perhaps you are looking at Panasonic's consumer AVCHD?

No - the mosquito noise was on an HMC150.

......he showed comparison frame grabs, where the codecs were stressed, and the AVC looked a tad better on the whole.....

If that's the test I think it is, the only comparisons I remember seeing were regarding how they compared in areas of high motion. (When yes, AVC-HD stood up well.) The comparisons of static detail I believe I saw in a separate test, and in this respect AVC-HD was inferior.

I've also seen that effect personally on an HMC150 in 1080i mode.

There are many ways of "stressing a codec" other than with motion, and the two most obvious are fine detail/sharp edges, and slowly changing gradients (especially coloured). Just because a codec performs well in one respect doesn't mean it will in the others.

(And different coders, different hardware, can give widely differing results, even if they are the same codec and same bitrate.)

Originally Posted by Robert M Wright

I'd love to see a similar (apples to apples) test (XDCAM EX vs AVCCAM with an EX1 or EX3) panning a res chart slowly.

Yes! And stationary as well. A sheet of newsprint might be an even better test as much of a res chart consists of blocks of uniform grey. The mosquito noise I observed was most obvious around high contrast sharp edges.

[Robert M Wright]

An HMC150 is going to show aliasing in 1080 line recordings of detailed images, even if recording uncompressed. The imaging block just can't resolve a high level of detail (low res chips).

[David Heath]

This wasn't aliasing, it was a compression issue. If it had been aliasing it would have been just as visible in 720 mode as 1080 - it wasn't. I was able to step frame by frame through the material and see a constant mosquito noise pattern for a number of frames before the pattern jumped, then be constant for a number more frames, then another jump.

I'm pretty sure the jumps corresponded to GOP intervals. Hence pretty sure that the codec is fairly fragile in respect of static detail, whilst being quite robust with respect to inter-frame movement.

Of course, this only applies to the coder in the HMC150 which is several years old in design now. That in the forthcoming Canon camera is newer, hence likely to be better.

[Robert M Wright]

I believe aliasing should show up more on 1080 line recordings (which goes beyond the HMC150 imaging block's ability to resolve detail cleanly).

[Perrone Ford]

Originally Posted by Simon Wyndham

Could be down to processing power (and hence power draw) of doing it realtime. Remember the Grass Valley Infinity? Recorded JPEG2000 and drew an absolutely huge amount of power.

How much is the RED drawing? It's writing essentially the same thing. And how much is Cineform's new recorder drawing? it's writing wavelet also. How about the SI-2K which is writing wavelet (Cineform RAW).