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Slow & Jerky Video

post #1 of 8
Thread Starter 
Machine: iMac G5 iSight, 500Gb HD (240Gb available), 2.5Gb RAM. 3 years and 4 months old.

In the last 4 months or so I have noticed the machine has generally slowed down and this is most notable when watching video in iTunes and separately via Quicktime. Nearly every video (no matter what size or quality) will stick and playback will be jerky.

The only software I have added in the last 4 months was the MacUpdate bundle in January that included VirusBarrier X5 and Drive Genius 2 (the two reasons I bought it). The only app of that bundle I have left installed is Drive Genius.

I have run 'repair permissions' in disc utility but that doesn't seem to have made a difference. Is it worth running defrag in Drive Genius or is there something else someone can suggest to get the 'snap' back?

I posted this question on the Apple Discussion Forums and got replies that I carried out but to no avail. They were, emptying caches (I installed OnyX for this) and doing an Archive and Install. The final thing I did was run the Apple Hardware Test from the install disc and it reported a clean bill of health!

Do I just have to accept the machine is over 3 years old so is going to be slower? It does seem strange that it just started happening for no apparent reason.

Regards

Fisher
post #2 of 8
I posted this question on the Apple Discussion Forums and got replies that I carried out but to no avail. They were, emptying caches (I installed OnyX for this) and doing an Archive and Install. The final thing I did was run the Apple Hardware Test from the install disc and it reported a clean bill of health!
post #3 of 8
Typically, jerky video indicates insufficient CPU power, but an iSight G5 is at least 1.9GHz, so I'd recommend checking Activity Monitor and ensuring that you don't have a large amount of CPU-intensive applications open. Safari and Firefox are also known to occasionally spike in terms of CPU usage, so try quitting them if they're open.

The other issue is video quality. HD video can be extremely taxing on the CPU, to the point that an iMac G5 might not be powerful enough to play HD video, especially in fullscreen mode or high-motion scenes. I actually had a Dell Studio 17 for a while (Core 2 Duo) that jumped slightly during Iron Man, specifically the scene where Tony tests the internal HUD UI on his Mark II suit. Generally, keeping the video at a smaller size (instead of fullscreen) increases clarity and framerate.
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post #4 of 8
Quote:
Originally Posted by Karelia View Post

Typically, jerky video indicates insufficient CPU power, but an iSight G5 is at least 1.9GHz, so I'd recommend checking Activity Monitor and ensuring that you don't have a large amount of CPU-intensive applications open. Safari and Firefox are also known to occasionally spike in terms of CPU usage, so try quitting them if they're open.

The other issue is video quality. HD video can be extremely taxing on the CPU, to the point that an iMac G5 might not be powerful enough to play HD video, especially in fullscreen mode or high-motion scenes. I actually had a Dell Studio 17 for a while (Core 2 Duo) that jumped slightly during Iron Man, specifically the scene where Tony tests the internal HUD UI on his Mark II suit. Generally, keeping the video at a smaller size (instead of fullscreen) increases clarity and framerate.

I have similar problem with my MBP 2.2 GHz SantaRosa. HD vids on YouTube was ok, and on Windows via BootCamp are ok, too. So hardware is not a issue.
So I reinstalled Flash Player 10 and everything was as it should be, but now already ISN'T !!! And I did not do anything unusual... no software installing, nothing..

Whats wrong?

thanx
post #5 of 8
Compression can also be a factor when dealing with HD vids. For instance, the Matroska Video File format (.mkv) utilizes very high compression ratios, resulting in a much smaller video file, which is great for uploading and streaming online. However, video players can't easily read that file quickly, especially when being asked to pan a lot. Another personal example is on my own setup, VLC can't really pan a .mkv video file without losing A/V sync, because it can't keep up with the decompression, even with a Core 2 Duo. Most of the various MPEG formats support HD, and while it produces a much larger file than Matroska, it is much smoother and easier to use.

But, you mentioned Flash Player. Are you viewing these videos from a website? If so, the website is almost (not always) always to blame. If you're viewing them from your hard drive however, it might help to know what video player and file format you're using.
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post #6 of 8
I mean Flash HD vids on website. Blame website? But the same video is playing good on Windows... so I thing webpage is OK. And that vids are not "realy" HD, just HQ on YouTube. Normal versions plays ok, but hd ver. are sooo slow even are full buffered.

Bye
post #7 of 8
Quote:
Originally Posted by BigMike81 View Post

I mean Flash HD vids on website. Blame website? But the same video is playing good on Windows... so I thing webpage is OK. And that vids are not "realy" HD, just HQ on YouTube. Normal versions plays ok, but hd ver. are sooo slow even are full buffered.

Bye

You folks are making me nervous! I am a PC user who is making the switch to an iMac. My wife is having the shaky video problem with a small two year old iMac. She asked my to try the same URL on my 7 year-old PC running XT. My 2560 X 1600 display was perfect. It seems to me that Apple would see this as a serious problem and send us a fix.
post #8 of 8
Quote:
Originally Posted by jimwork View Post

You folks are making me nervous! I am a PC user who is making the switch to an iMac. My wife is having the shaky video problem with a small two year old iMac. She asked my to try the same URL on my 7 year-old PC running XT. My 2560 X 1600 display was perfect. It seems to me that Apple would see this as a serious problem and send us a fix.

My wife has a brand new MacBook that we watch HD video online and offline on all the time and there's no shaky video. I have a brand new MacBook Pro, same deal. (For the record, brand new is 9 months old and 3 months old respectively) I suspect for the original poster it's an issue with the video card. And older video card probably doesn't have enough memory to handle the video. We both have 256mb of VRAM. Go to "About This Mac" and check how much you have. I'm not sure what a bottom end would be, but if it's significantly lower than 256mb you might consider buying a new video card.

The aforementioned alternate issues are also reasonable. If you have too many other applications open, your CPU and RAM get eaten up which makes everything operate more slowly. Also, Web sites are often the issue. Streaming higher resolution videos takes up more bandwidth and dozens of factors could slow down the stream. Try letting the video buffer for a while longer. Still super choppy? Check out the physical genius bar, they're alright too.
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