Latest AVCHD Format Standard Supports 3D Content

[Dave Campbell]

Today the companies have jointly released the AVCHD Format to Version 2.0, which supports AVCHD 3D and 1080/60p,50p video.

AVCHD Progressive 1080/60p/50p will be supported by Sony's Handycam and Cyber-shot models that will be released this year. Not sure what this means since cameras today shot 1080/60p 59.97 I think? Or, is this something different?

[Jack Zhang]

It's 1080p59.94 at 28mbps. (NTSC) They currently call it "Original Format".

However, I think bitrates certainly need to increase in order for this to be a proper acquisition format. As consumer cards/SSDs get faster, don't be surprised to see a few 50mbps offerings for 1080p60 coming soon. (albeit only 4:2:0)

The pro market is also currently left cold with Panasonic's AVC-Ultra going vaporware. The real goal for prosumers is 10bit, 4:2:2 1080p60 full raster, all of which AVC-Ultra was to deliver.

[David Heath]

Originally Posted by Jack Zhang

It's 1080p59.94 at 28mbps. (NTSC) They currently call it "Original Format".

However, I think bitrates certainly need to increase in order for this to be a proper acquisition format.

Don't knock the 28Mbs rate. What's likely to be the case is that the *TIME* between I-frames will likely stay the same between 25p/50p - every half second, say - so effectively twice as many difference frames between the I-frames for 50p as 25p. Double the GOP rate, keep the I-frame interval the same, in other words.

And because they occur every 1/50 sec now, the frame by frame differences will be far less than when they were every 1/25 sec. So less difference to code.

Hence you don't need anything like as much as twice the bitrate to code 50p cf 25p, even though it may seem like it should be the case at first sight. Hence expect 50p/28Mbs to give pretty similar compression quality to 25p/24Mbs.

10bit, 4:2:2 1080p60 full raster may come along - but don't then expect it to be AVC-HD. If you want those features, it's likely you'll want a codec which needs less power to code/decode as well, that may well come about - but won't be AVC-HD.

[Jack Zhang]

Artifacts are much more noticeable at 28mbps than at a higher mbps. Look at this sample of waves crashing:

Oasis of the Seas (Native MTS Clip) on Vimeo

There are macroblocks galore if you go frame by frame on the video as the waves are crashing. Doubling the bitrate would mitigate this kind of problem.

[David Heath]

Originally Posted by Jack Zhang

Artifacts are much more noticeable at 28mbps than at a higher mbps. .......... Doubling the bitrate would mitigate this kind of problem.

But you have to ask what it would have been like at 24Mbs/25p....... I don't dispute the higher the bitrate, the better (all else equal), but we're talking here about AVC-HD, and the point I'm trying to get across is that 25 to 50 fps may seem you'd have to double the bitrate for equivalent quality - practically, you don't, for the reasons I gave above.

You may also feel any of the AVC-HD specified bitrates are not enough - be it for 25p or 50p - but AVC-HD is specified as a replacement for HDV, it's intended for consumer and low end prosumer work - not high end professional. There's a place certainly for higher than 28Mbs recording - but not within the AVC-HD spec.

For the camera front ends that currently have AVC-HD backend recording, then with the possible exception of the FS100, (haven't measured it) then all of them are likely to have noise figures that would make 10 bit recording a total waste of time and bitrate. All it would do is necessarily up the bitrate from 28 to 35 Mbs (for equivalent quality) just to code the noise more accurately!

Pay more money, get better front ends, and 10 bit recording starts to have a point - but then we're moving away from AVC-HD.

[Dave Blackhurst]

Just seems to me that video looked pretty good unless you pixel peep to the extreme. I looked at it, wasn't "bad" on my 1920x1080 monitor...

There's a point of diminishing returns, where most people will NEVER see the "improvements"... on the flip side, the 28Mbps 1080p was added to the spec, since apparently it was already economical to offer the format in $400 point and shoot cameras... who's to say that next year "35" won't be the number of the year?

I guess a glass half full approach makes more sense to me - they are extending the format and improving the quality, next year it'll probably happen again...

I think the point of the formats beginning to exceed the capability of the hardware to capture and play back is a valid one. While "data handling" of course improves all the time, you have to be able to support "legacy" displays, and on the capture end, your hardware has to improve or be more expensive. When you consider what you CAN buy in a sub $1K price range, it's pretty amazing I think!