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AVCHD Format Discussion
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Old October 12th, 2006, 10:52 PM   #16
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It is early in the game but so far people who have been burning home brew HD o n red dvd's have AFIK only been able to get them to play on HD DVD players and NOT Blu ray (samsung) players.


I would not put it past Sony to have worked out something to prevent this from happening. It is also likely that avchd will not be supported in the short term on HD DVD players


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Old October 12th, 2006, 10:53 PM   #17
 
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Quote:
Originally Posted by Graham Hickling
I thought this was odd (from that nvvtd review): "...the idea is to allow consumers to burn their own AVCHD videos direct to Blu-ray discs... with HDV, on the other hand, there would need to be a transcoding step (MPEG-2 to H.264) ..."

That's not correct is it?? Blu-ray supports MPEG2....
BD supports MPEG 2, MPEG 4/h.264Pt10/AVC (all the same) and VC1 in the standard. No transcoding necessary.

Quote:
Originally Posted by Sharyn Ferrick
It is early in the game but so far people who have been burning home brew HD o n red dvd's have AFIK only been able to get them to play on HD DVD players and NOT Blu ray (samsung) players.
I would not put it past Sony to have worked out something to prevent this from happening. It is also likely that avchd will not be supported in the short term on HD DVD players
What possible reason could Sony have to prevent "home brew" HD from playing on a BD player of *any* kind? As long as it's legal, it's a profit to them no matter how you strike it. Blank BD disc...Sony BD player...Maybe authored on Sony BD authoring tools...
The bigger problem is that all the developers that jumped the gun and screamed "We offer BD support" essentially made up whatever they needed to make up in order to market their software last year. Notice that of *all* the software developers, Sony is the *only* company that didn't stand up and scream "Our authoring tools support BD."
Because Sony knew the spec had not yet been settled.
It is indeed, very early in the game. For those that weren't around during the transition from 1630 masters to CD, consider this a very fast game nowadays, and be glad that you even have access to it this fast. I don't mean this to be a "way back in the day" story, but the short version is...waiting even 2 years for desktop HD is nuthin' compared to desktop CD "back in the day."

It's ludicrous to assume that Sony would try to disallow one format or another. Read the spec. There are three supported formats. If someone doesn't conform to that format, it's not Sony's fault, or the fault of any member of the BD consortium. Just like the fact that you can't burn an MP4 to a standard DVD and expect it to play on every DVD player out there today.
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Old October 15th, 2006, 04:17 AM   #18
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AVCHD is better then mpeg2...at low bitrates. At high bitrates (hdv-high) the biggest difference is that avchd needs a lot more processing power and it doesn't look much better at all.
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Old October 15th, 2006, 05:29 AM   #19
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Quote:
Originally Posted by Douglas Spotted Eagle
BD supports MPEG 2, MPEG 4/h.264Pt10/AVC (all the same) and VC1 in the standard. No transcoding necessary.



What possible reason could Sony have to prevent "home brew" HD from playing on a BD player of *any* kind? As long as it's legal, it's a profit to them no matter how you strike it.
today.
Hey SPOT
I think you misread my post, I am talking about HD on a standard Red Laser Dvd blank, not user created BD's.

I think it is very much in Sony's interest to try to control the use of HD redlaser dvd's in it BD players to AVCHD.

Sure on BD they will let you do anything that is legal.

We will see,

Sharyn
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Old October 15th, 2006, 09:17 AM   #20
 
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You're right, Sharyn, i misunderstood your original point. That said, BD is supposed to be backwards compatible. Therefore, if you have a red-laser/standard DVD with HD content that will play on a standard, non BD-DVD player, it should play on a BD player. Again, it's not in anyone's best interests to do otherwise. Aside from that, Sony doesn't control the market in that regard. If they make a deck that won't play, Samsung, Hitachi, Panasonic, Teac, or one of them surely will do so.
The only issue at question in my mind, is licensing. Microsoft (Bill Gates personally) told Sony that they will be very specific as to how they license VC decoders. That could be a major issue for some folks depending on how that goes.
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Old October 19th, 2006, 04:17 PM   #21
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AVCHD is better than HDV at any bit-rate

Quote:
Originally Posted by Mikko Lopponen
AVCHD is better then mpeg2...at low bitrates. At high bitrates (hdv-high) the biggest difference is that avchd needs a lot more processing power and it doesn't look much better at all.
I want to see substantiation for your claim of "doesn't look much better at all". What were your comparison parameters? As for the processing power - we're getting it, no worries.

To me it is harder to produce decent-looking video at lower bit-rates. And if more bandwidth is available - so much the better, even more information can be squeezed in - up to the limit of the imager. Please understand that in fact you're arguing not with me but with the math (and it is a lot less forgiving :-).
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Old October 19th, 2006, 04:28 PM   #22
 
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Originally Posted by Uri Blumenthal
I want to see substantiation for your claim of "doesn't look much better at all". What were your comparison parameters? As for the processing power - we're getting it, no worries.

To me it is harder to produce decent-looking video at lower bit-rates. And if more bandwidth is available - so much the better, even more information can be squeezed in - up to the limit of the imager. Please understand that in fact you're arguing not with me but with the math (and it is a lot less forgiving :-).
Mikko doesn't need comparisons; it's fairly well known, easily demonstrable that AVC is only better in lower bitrates. As bitrate goes up, efficiency goes down.
If low bitrates are your target, then these might just be the camcorder for you. However, as the marketing engines crank up, simply accepting that "AVCHD is twice as efficient as HDV" is foolish and could lead to some bad choices, depending on your goal. If low bitrate vid is your goal, then AVCHD may well be in your best interests.
As far as horsepower....we're a long, long way from being there. However, intermediary codecs make a huge difference, and that'll be the best workflow in the short-mid term.
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Old October 21st, 2006, 05:14 AM   #23
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Originally Posted by Uri Blumenthal
Please understand that in fact you're arguing not with me but with the math (and it is a lot less forgiving :-).
Well the math is pretty simple. Once you start going closer and closer to intraframe codec bitrates (like dv) then you lose AVCHD's abilities to track pixels and smooth artifacts. Because once a bitrate is high enough you don't need them. This is about where HDV and AVCHD stand. HDV is 25mbps, AVCHD cameras are about 15 max. This is not good enough.

What happens if dv-files would be encoded with AVCHD instead of dv (just like mjpeg)? Would it look better? No way. It would look worse, because the bitrate is so high the mjpeg does a better job. Granted mpeg2 isn't intraframe either, but the bitrate is still quite high so the gop can be kept at 12/15. If the gop was about 30-300 then AVCHD would get more advantage as it could use it's superior tracking to track pixels.

I've watched AVCHD clips and haven't been that pleased. Firstly my machine doesn't run the file nearly as well as HDV. Secondly the image quality isn't better at all, it's actually a bit worse in terms of noise as the AVCHD codec seems to add it to enhance texture. Mpeg2 doesn't but it can create blocks more easily.

Now if you start increasing AVCHD's bitrate to about 25 then yeah, it can look a bit better as there's still headroom to go. But it's not like "omg AVCHD IS 2x BETTER!" especially considering the power requirements.

The same happens when you compare high-bitrate mpeg1 to high bitrate divx or xvid. Mpeg1 will look better. But divx and xvid are way better in lower bitrates.
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Old October 21st, 2006, 05:45 PM   #24
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Quote:
Originally Posted by Mikko Lopponen
Well the math is pretty simple. Once you start going closer and closer to intraframe codec bitrates (like dv) then you lose AVCHD's abilities to track pixels and smooth artifacts. Because once a bitrate is high enough you don't need them.
Given that DV is less than ideal for recording SD resolution at 25 Mbps, why shouldn't we expect that a more modern codec would be appropriate for recording HD resolution at the same bit rate? Heck, even at 50 Mbps HD would still be heavily compressed, so why wouldn't AVCHD work well under those conditions? Seems to me that either MPEG2 or AVC at around 50 Mbps would be a fine compromise for recording HD, and the sooner someone makes a camera based on that at a reasonable price the better.

And it makes no sense to say that any codec looks better at a low bit rate than at a higher one; just that the differences between codecs are less obvious as bit rate increases.
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Old October 22nd, 2006, 09:57 PM   #25
 
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Originally Posted by Douglas Spotted Eagle
Mikko doesn't need comparisons; it's fairly well known, easily demonstrable that AVC is only better in lower bitrates. As bitrate goes up, efficiency goes down.
Please provide a link to a reputable source to support this statement.

Thanks.

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Old October 22nd, 2006, 09:59 PM   #26
 
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Originally Posted by Kevin Shaw
And it makes no sense to say that any codec looks better at a low bit rate than at a higher one;
Agree.

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Old October 23rd, 2006, 12:03 AM   #27
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>>>And it makes no sense to say that any codec looks better at a low bit rate than at a higher one

That's not what he means. He's saying that divx and xvid encoded at a low bitrate will look BETTER THAN MPEG1 encoded at the same low bitrate ..... whereas xvid and divx encoded at high bitrates will NOT look better than MPEG1 encoded at that same high bitrate.
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Old October 23rd, 2006, 01:09 AM   #28
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Originally Posted by Graham Hickling
He's saying that divx and xvid encoded at a low bitrate will look BETTER THAN MPEG1 encoded at the same low bitrate ..... whereas xvid and divx encoded at high bitrates will NOT look better than MPEG1 encoded at that same high bitrate.
Fair enough, but do we have any real indication yet how AVCHD recorded at 25+ Mbps might look compared to HDV? I've been skeptical about AVCHD from the start, but it seems plausible it could offer advantages for representing an HD image at such a bit rate. Or if someone like Panasonic gives AVCHD more bandwidth than HDV, then what?

On a related note, how might AVCHD-intra at 50 Mbps compare to DVCPro HD at 100 Mbps?
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Old October 23rd, 2006, 02:30 AM   #29
 
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Originally Posted by Kevin Shaw
On a related note, how might AVCHD-intra at 50 Mbps compare to DVCPro HD at 100 Mbps?
Actually, there is no "AVCHD-Intra."

Instead, it should be written as "AVC-Intra."

AVC-Intra = I-Frame.

AVCHD = Long GOP.

Both AVC-Intra and AVCHD are H.264-compliant.

H.264 is the future.

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Old October 23rd, 2006, 07:10 AM   #30
 
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Quote:
Originally Posted by Jerry Jones
Please provide a link to a reputable source to support this statement.

Thanks.

- Jerry Jones
Rather than looking for a "reputable source" to support this (since apparently the MPEG isn't reputable), you might spend a few minutes encoding test patterns in various codecs at various bitrates. You'll find very quickly that comparatives do indeed demonstrate what MPEG says, what Sony has demonstrated, and what others on websites such as Doom, etc have had to say.
With some codecs, as the efficiency goes down with corresponding rising bitrates, artifacts or other issues begin to appear. Other codecs are weakest at low bitrates, while others appear with a good image but the bitrate is so high that it's an inefficient choice for the desired payload/quality.
Read my comment again; AVCHD is only "better" (better implying high quality image for low bitrate, ie; more efficient) at low bitrates as compared to higher bitrates in other formats. The blanket statement of "AVCHD is twice as efficient as MPEG2" doesn't work, because the efficiency isn't linear.
And AVC-I...we'll just have to see how that works, won't we? Using I-frames only, completely negates the entire value of how AVC operates in the first place, so it'll be very interesting to see how that pans out. 992Mbps down to 50Mbps with no loss....That'll be some interesting discussion when there are actual images to compare.
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