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(MPG4) Sanyo Xacti (all models)
A compact 720p MPEG4 digital media camera recording to SD Card.


 
 
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Old April 3rd, 2006, 03:14 AM   #16
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Many thanks for the replies, chappies. Yes I guess I will at some point get a HDTV so it should be worthwhile in time to come. I forgot to say I just moved up from a crappy Sony DSC-9 stills camera that took tiny mpegs!

I guess I don't like the HD version too much in that the playback files seem to stutter/stop/start on my computer (a PIV 3 ghz with 1gig ram). Am I doing something wrong?

Cheers all

Len
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Old April 3rd, 2006, 08:39 AM   #17
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Hi Leonard,

I'd be betting it's your video card. Check if your system has dedicated video memory, and how much it has. A lot of systems nowadays use SMA technology to produce video. It's sort of a poor-man's display where computer memory is allocated to video instead of dedicated video. The result is poor graphical performance on otherwise fast machines. You would only notice it when trying to play complex video or grahically intense games. Manufacturers use this technology because it reduces production costs and isn't detrimental to basic users.

There are two ways to check your video archetecture. The first is your computer manual or spec book. The second (and somewhat easier) is Windows. Double-click system from within control panel. Check the amount of RAM you have, compared to what you purchased. If it reads as less than you purchased, it's due to SMA archetecture. In your case, you should see either 1024MB or 1GB of available system RAM. You can tell how much your video card is using by subtracting what Windows reports you have for RAM from the 1024MB you should have. Most SMA systems thieve 32, 64, or 128MB of system RAM and all theive a minimum of 16MB.

If you have SMA archetecture in your system all is not lost. The addition of a quality video card is an inexpensive option; it will increase the performance of your graphics system to match your otherwise fast computer.

Note: Windows is known to report .99GB of system memory. If yours does this, it' a Windows issue and you don't have SMA.

Note 2: A poor-man's solution to this problem is to increase the amount of memory allocated to video through SMA. Your ownder's manual will tell you how to do this if it can be done. You can try your maximum setting and see how much it helps. If the SMA is well designed (doubtful), you'll get a performance boost.
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Old April 3rd, 2006, 03:54 PM   #18
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Graham,

Replying to your comment:

"David, I think the difficulty with saying HD was "a laboratory thing" until '97 is that it may create the impression they were struggling with design until that date."

Actually, they were struugling with design. They had been able to make HD pictures for a number of years, but they couldn't fit into the six MHz bandwidth of the NTSC channels. They were VERY reluctant to take three channels for one HDTV channel as analog would have required. It wasn't until digital compression techniques could make much more efficient use of the RF spectrum, that things moved forward. As you can imagine, that took awhile since standards must be set, and that took agreement between a number of interested parties. They even changed the aspect ratio to 16:9 - and took a long time arguing about THAT!

There were the digital compression techniques - MPEG2 was chosen in the US with a data rate of about 19 MHz, which could be fit into the existing 6MHz channel using 8VSB modulation. An extra channel was GIVEN to each broadcaster for simultaneous digital and analog broadcasting. The analog channel must be retired in February 2009.

The satellite companies BEGAN using digital since it was more efficient. They could do anything they wanted, since they provided the receivers for their signal. Right now DirecTv is switching to MPEG4. Very expensive, since EVERYTHING must be updated. MPEG4 can compress twice as efficiently as MPEG2. Cable is switching to digital, since it is so much more efficient - but expensive to convert. Comcast in my area is only purchasing receivers capable of HD.

The distribution network was necessary before production became economically feasible. They're STILL argueing over HD DVDs!
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Old April 3rd, 2006, 04:11 PM   #19
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Okay, I said the market wasn't ready when I should have said that the infrastructure wasn't ready.

But as you acknowledge, the design of the HD format itself was indeed achieved considerably earlier than 1997.

That was the only point I was making! :)
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Old April 4th, 2006, 07:16 AM   #20
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Chris, thank you kindly for taking the time to explain the possibilities. I shall definitely try them out - probably end up getting a new video card - the existing one is quite weak.

Cheers
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Old April 4th, 2006, 04:19 PM   #21
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Quote:
Originally Posted by Leonard Ng
<snip>
I guess I don't like the HD version too much in that the playback files seem to stutter/stop/start on my computer (a PIV 3 ghz with 1gig ram). Am I doing something wrong?

Cheers all

Len
Len, There's likely nothing wrong with your computer, even if it has shared video memory. You just need the right software and configuration. Even VLC would probably work on a 3.0 GHz Pentium 4, though it uses more CPU than the best DirectShow decoders. Make sure you use the hardware overlay and acceleration and, if you have a pre-DirectX 8 video card, you probably do need a AGP video card upgrade. I've posted some suggested software elsewhere in these forums that you could try. Search for my name.

If shared memory is architected correctly, there should be no problem. The new Intel Mac minis have shared video memory. I've seen some OpenGL Cinebench benchmarks achieved by the Apple Intel Dev platforms that were amazing for an integrated graphics adapter WITH shared memory (the Intel GMA 950 video controller). They were actually faster in these benchmarks than the production Intel Macs without shared memory! So shared memory alone does not determine video performance. It's funny how Apple marketing used to 'dis competitor's systems with shared memory and now they're using shared memory Intel architecture on some of the new Intel Macs!

I was playing with the Mac mini Core Duo model and it just screams for for video playback. VLC rendered my Sanyo HD1 HD videos without a glitch (unlike Quicktime, which is H.263-challenged) and the Core Duo Quicktime played the Apple AVC (H.264) 1080i X 24fps Batman trailer without dropping frames. It used to take a fast Dual G5 Power Mac to do that! It accomplished this all with shared video memory! The mini may not be the best gamer machine, for many reasons, but it's great for video!
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Old April 4th, 2006, 05:21 PM   #22
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Perhaps the best recommendation to one with poor graphical performance is to test the video. Here is a test application you can run... it's free. I've never been much of an advocate for these programs, as they can be tweaked to make certain cards look better when they aren't. Still, they do suffice for limited testing.

http://www.passmark.com/products/pt.htm

You might also try this test:

http://www.futuremark.com/download/?3dmark06.shtml

Compare your results to established benchmarks (in the apps and on the net).

Colin, I agree in part, but the bulk of SMA graphics systems are poor performers. The cards you present are great performers, but they are the exception to the rule. I recall a review of P4 desktops I read on Tom's Hardware not six months ago, in which six SMA-based systems achieved the lowest video benchmarks of twenty systems tested. The top five performers in the graphics area leveraged dedicated video memory.

Also, for what it's worth, I tested nearly fourty laptops before I bought the one I have (64MB dedicated, 1 year ago) and found that systems that used SMA weren't even fast enough to complete the tests, let alone score well on them. The tests used were 3Dmark.
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Old April 4th, 2006, 07:41 PM   #23
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Quote:
Originally Posted by Chris Wells
Also, for what it's worth, I tested nearly fourty laptops before I bought the one I have (64MB dedicated, 1 year ago) and found that systems that used SMA weren't even fast enough to complete the tests, let alone score well on them. The tests used were 3Dmark.
I think 3Dmark is probably a good benchmark for gaming, but I'm not a gamer and I'm actually not really an expert in benchmarks either. I know that decent video playback is possible even without 3D video acceleration, though many modern video DSFs are certainly designed to use 3D accleration. You could google for Cinebench too. It seems to have many tests directly applicable to video playback, like OpenGL. I don't remember if it contains any tests for DxVA acceleration, however. With the right video card and software, DxVA offers the highest potential for low CPU usage. For example, 1080i mpeg2 playback runs as low as 20% CPU (with deinterlacing) on my HTPC when using DxVA. Normally mpeg2 and H.263 require roughly the same processing capability but not with DxVA because, unfortunately, H.263 decoders don't seem to be available for DxVA acceleration and the DxVA mpeg2 decoders have a significant advantage. So DxVA doesn't help us with our HD1 files (as far as I know).

In the end, even HD video playback isn't all that demanding of modern memory systems (video or main memory) , if the software is good It's mostly about CPU power for H.263 and, to a lesser extent, video acceleration. Depending on the software. SSE and SSE2 instructions can help quite a bit as does MMX, but MMX is available on nearly any recent x86 CPU.

Chris, Your assertion that most shared memory graphics subsystems score low in benchmarks seems correct to me. After all, they do it to reduce costs, but they do an lot of other cost cutting in such a machine too. Yes, the example I gave were not low cost systems and they don't perform as such, even though they use shared memory. On the other hand, even low benchmark scores don't rule out acceptable playback. Good enough is good enough so I usually "benchmark" with actual applications and software.

Last edited by Calin Brabandt; April 4th, 2006 at 07:47 PM. Reason: adds
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Old April 5th, 2006, 11:43 AM   #24
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Chris and Calin, thanks very much; I shall run those tests. To be honest, much of it goes way over my head, but this is an excellent forum for learning. I was hoping the HD-1 experience would be a little bit more idiot-proof but hey that's life :)

Many thanks again

Leonard
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Old April 13th, 2006, 05:48 AM   #25
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Side by side comparison of HD1 and C6 including test of each below.

Valuable because the guy shot almost precisely the same location/angle/date/time with both cams.

http://forums.dpreview.com/forums/re...ssage=17525535
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