ilauzirika
Boring Senior Member
and if the codec isn't enough for you, the hdmi out is always there.
Press Release: HMC150, "the new DVX"
- Thread starter Barry_Green
- Start date
Robert M Wright
Well-known member
Recording from the HDMI port isn't practical (yet) for mobile shooting.
Robert M Wright
Well-known member
IMO Panasonic would be wise to build 24mbps recording into the HMC150. If they don't (and set the maximum bitrate at like 17mbps) they would be leaving themselves wide open for Canon to come along with a modified A1 (with 24mbps AVCHD recording - which would be real easy for Canon to do) and just blow the HMC150 out of the water.
Barry_Green
Moderator
Excellent point -- once the recording time exceeds the battery's runtime, it's starting to render the idea of needing multiple slots a little moot.
Barry_Green
Moderator
18 megabits should be enough to get the job done; Sony says that AVC is two to 2.5 times as efficient as MPEG-2. At 20 megabits I'd be very surprised if AVC-HD wasn't as robust as XDCAM-EX's 35 megabits. At 24 megabits it seems impossible that AVC-HD wouldn't be as good or better than XDCAM-EX.
Of course, this is talking only about the recording format, with no consideration given to the camera imaging head!
Barry_Green
Moderator
13 is the highest listed in the press release, and that's in the ballpark for matching HDV. Other cameras have pushed it as high as 17mbps; doesn't the Panasonic SD9 do 17mbps?
17's pretty good, especially if it's progressive. XDCAM-EX is quite robust, but not so much in its interlaced form. I found the progressive scan version resilient to artifacting, but the 1080/60i can get macroblocked like HDV when things start to go south. I would expect AVC to perform similarly, so if we're talking about 17mbps of progressive-scan that should be much better than 17mbps of 1080i.
I don't know what the holdup is on people releasing higher bitrates, but I've got to assume it's something on the line of chip processing power; we don't have quad-core laptops yet, and we don't have 24mbps AVC-HD yet. But we can certainly expect at least 17mbps, and I'm hoping it's 20 to 24.
Nobody's put out higher than 17 yet. I can't believe it's some grand conspiracy to hold us down, but instead it has to be something to do with the hardware. You can't get a 6-gigahertz Core 2 Duo chip yet, and I'll bet it's for the same reason.
Robert M Wright
Well-known member
It seems that the potential (image quality) efficiency of AVC isn't being realized as yet, in codec implementations in cameras. AVC is very computation intensive. I can imagine the camera makers are struggling with designing AVC encoding chips that are both efficient (image quality wise) and energy efficient (as well as being small and running cool enough). I don't see any reason why the bitrate can't be cranked up though (with the same quality efficiency per bit).
There are quad core laptops being made, but I don't think there are any that use chips designed to run with lower power consumption than desktops.
There are quad core laptops being made, but I don't think there are any that use chips designed to run with lower power consumption than desktops.
Robert M Wright
Well-known member
Probably the biggest reason that bitrates have been kept down thus far is to keep recording lengths for mini DVDs and flash memory reasonably long. All of the AVCHD cameras to date have been consumer cameras. Cranking AVCHD to 24mbps would make recording lengths on mini DVDs pretty short, and flash memory prices were considerably higher (and capacities lower) when most consumer AVCHD cameras were designed.
William_Robinette
Shallow Member
And "! 5 Hours of Record Time !" beats "! 24mbps Recording !" in the consumer world.
Different story. But, with the introduction of 45nm processors the concept of "desktop" power consumption because very low. If laptop matches that, it's no longer as bad as say four years ago when you were dealing with Pentium D processors.
Barry_Green
Moderator
Yeah, but... I'm not buying that part of the argument, because AVC-HD is inherently scalable. Every AVC-HD camera out there lets you choose bitrates, IINM. I think every one of them goes down as low as 6mbps, and I know the HSC1U lets you choose between 6, 9, and 13... don't all of them offer similar capability? If so, the limited-record-time argument doesn't hold water -- you've always got the option to record at a lower bitrate.
BobDiaz
The Professor
As far as CODECs go, nothing is ever exact, but assume equal video input and very good quality CODECs, the range of around 13Mbps to 18Mbps is where the MPEG-4 AVC H.264 starts to match the 35Mbps MPEG-2 of the EX-1.
As I recall, Barry had a hard time breaking up the EX-1's CODEC with excessive movement. It was possible, but a simple pan would not do it.
Assuming a very good CODEC, IF Panasonic selects 18Mbps for the maximum bit rate, the results should be very good under almost every shooting condition. Having a higher bit rate is a plus, because that gives us more head room in case the shot has lots of extreme movement in it. (I won't cry if the maximum bit rate is limited to 18Mbps, but anything higher will always be better.)
With any MPEG CODEC, Progressive always does better than Interlaced. For example, 1080/60i and 1080/30p have exactly the same number of pixels per second, BUT the 30p compresses with less artifacts. Depending on how the Interlaced is compressed (60 of 1920x540 _OR_ 30 of 1920x1080, per second), either we have a lot of vertical up/down movement _OR_ we have feathering.
Either way will burn up bits that won't be required for Progressive.
Bob Diaz
As I recall, Barry had a hard time breaking up the EX-1's CODEC with excessive movement. It was possible, but a simple pan would not do it.
Assuming a very good CODEC, IF Panasonic selects 18Mbps for the maximum bit rate, the results should be very good under almost every shooting condition. Having a higher bit rate is a plus, because that gives us more head room in case the shot has lots of extreme movement in it. (I won't cry if the maximum bit rate is limited to 18Mbps, but anything higher will always be better.)
With any MPEG CODEC, Progressive always does better than Interlaced. For example, 1080/60i and 1080/30p have exactly the same number of pixels per second, BUT the 30p compresses with less artifacts. Depending on how the Interlaced is compressed (60 of 1920x540 _OR_ 30 of 1920x1080, per second), either we have a lot of vertical up/down movement _OR_ we have feathering.
Either way will burn up bits that won't be required for Progressive.
Bob Diaz
this is a stupid question but does anyone know if this will take MiniDv tapes? and shoot SD like the HVX?
Because if it does, this is really going to be a DVX killer and no one will buy the DVX any more, so it makes sense why Panasonic is giving a rebate right now. trying to get ride of it...haha
Because if it does, this is really going to be a DVX killer and no one will buy the DVX any more, so it makes sense why Panasonic is giving a rebate right now. trying to get ride of it...haha
I hope not. Who wants to deal with tape? No tape! 100% solid state. Lower on power and definately FASTER on workflow!
Robert M Wright
Well-known member
Consumer cameras aren't exactly chalk full of options (of any sort). The manufacturers tend to keep them pretty simple. I'm sure that when camera makers looked at the consumer market, they didn't see a big demand for super high quality compression at the expense of extremely short recording times. Look at the mini DVD AVCHD camcorders. If those offered 24mbps recording, the disks would only hold something like 15 minutes of video (that's a real rough number, off the top of my head). Another factor is, that going to bitrates higher than 13mbps just wouldn't work with common flash memory (to slow). When most the AVCHD flash memory cameras were designed, memory capable of recording higher bitrates was neither inexpensive nor widely available. That has changed drastically in the last year, and now Panasonic just came out with the SD9 that can record at 17mbps. If you look at standard def mini DVD cameras, you might notice that none of them even record MPEG2 that reaches the maximum bitrate for DVD video specs. Consumers don't demand very high quality, and they don't get it either.
ilauzirika
Boring Senior Member
and it just adds to the manufacturing cost, better keep it lower.
Considering how often Panasonic updates its prosumer offerings, it'll have to live with the camera for the next 2 to 3 years. If it does anything less than the 24-Mbps maximum, the HMC150 will be in danger of becoming outdated when somebody else releases a 24-Mbps model. Even at 24 Mbps, the data rate is less than 1080i HDV's, so the rate itself is low enough for SD cards to still have substantial recording capacities.
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Robert M Wright
Well-known member
When you consider the 35mbps MPEG2 bitrate of the EX1, it's easy to think that it is a big jump up from the HDV 24mbps MPEG2 bitrate, but it isn't. It's actually only about a 10% increase in bitrate (but it is a variable bitrate, which helps boost overall quality). When the EX1 is in HQ recording mode, it is compressing a 1920x1080 image at 16.88bps per pixel. With HDV 24mbps MPEG2 compression, a 1440x1080 image is being compressed at approximately 15.43bps per pixel. (At 35mbps total, the bigger XDCAMS record 1440x1080 at 22.51bps per pixel, which is a significant increase in bitrate per pixel over the EX1 or HDV cameras.)
Neither HDV nor the EX1's 35mbps HQ mode is what could be termed visually lossless compression, although both work pretty well. Either one is just fine for delivery quality. Either one works pretty well for acquisition in most circumstances. Neither one is well suited for multi-generation re-compression.
Since AVCHD compresses 1440x1080 images (and can potentially achieve better than 2x image quality results, compared to MPEG2), 13mbps-18mbps AVCHD potentially could yield image quality that is equal to or better than what is achieved in the EX1 (or HDV cameras), but it still wouldn't be what could be termed visually lossless (even if the h.264 implementation is excellent). 24mbps would get a lot closer to that (potentially rivaling the bigger XDCAMS).
Barry_Green
Moderator
The EX1's 35mbps VBR mode is much, much, much better than HDV though. Way more than the numbers would indicate. Three years of learning about compression efficiency really paid off. It's not infallible, but HDV would totally fall apart under scenarios where XDCAM-EX doesn't even really blink. You can't compare the two by the numbers. I originally thought the same as you, that it'd be a little better, but in reality it's much better than HDV.
I expect even better from AVC-HD. With adequate bitrate, it should be fantastic. I've seen it at 8mbps, projected, and it looked great; it looked as good as HDV at 25mbps. At 20mbps it should be every bit as good as XDCAM EX.
Also, AVC-HD has support for 1920x1080 as well as 1440x1080.
And neither system will come close to "visually lossless". They're both long-GOP 4:2:0 highly-compressed systems.
I expect even better from AVC-HD. With adequate bitrate, it should be fantastic. I've seen it at 8mbps, projected, and it looked great; it looked as good as HDV at 25mbps. At 20mbps it should be every bit as good as XDCAM EX.
Also, AVC-HD has support for 1920x1080 as well as 1440x1080.
And neither system will come close to "visually lossless". They're both long-GOP 4:2:0 highly-compressed systems.
The bigger XDCAMS right now use 35mbps but on 1440x1080, instead of 1920x1080 like the EX1 does. I don't know how the compression efficiency fares as compared to the EX1, but I wouldn't be surprised if it's not as good as the EX1. The bigger cams came out quite a while before the EX1 did and as such they may not share in the same improvements the EX1 got.
Robert M Wright
Well-known member
Neither HDV nor XDCAM are very old. It's difficult to conceive that Sony made that much improvement to their MPEG2 encoding algorithms (MPEG2 has been around quite awhile and doesn't take a ton of CPU power either), but the VBR implementation in the EX1 could be a considerable improvement (and explain the differences you observed). The EX1's peak bitrate really isn't very constrained by the bandwidth available from the media that is being recorded to, and that could go a long way toward explaining why Sony went with expensive SxS cards too (rather than more conventional flash memory). Panasonic (and other camera makers) are much more constrained on the peak bitrate they can use with AVCHD cameras (that use conventional flash memory).