Problem with Warner Bros Blu-rays

[dmemphis]

Hi all
1st post here,
i've recently ripped 2 warner bros blu ray dvds using anydvd hd ( natural born killers & lethal weapon ) both ripped fine but on playback are jerky! any ideas or is it just some work some don't?
i did also rip batman begins which plays ok ( smoothly ) now thats ( compared to the other 2 here i've mentioned ) a more up to date warner bros blu ray which i thought after the other 2 would most certainly be a problem but it wasn't! i've ripped all 3 the same and they all are uk region B's.
cheers Rob...

[Adbear]

More information please. Log files, how are you playing them, system specs etc

[dmemphis]

Sorry ripped them to hard drive, playing from external hard drive connected to mac mini intel 2GHz core 2 duo, leopard operating system, using plex media player connected by dvi to hdmi on full 1080p hd lcd

[Adbear]

I suspect that it's going to be down to the system not being up to playing it, is there any way to check cpu usage whilst it's playing? I have problems with a few discs playing on a 2.16 C2D using PowerDVD when it doesn't have a graphics card it can use to offload on to

[dmemphis]

hi thanks for reply, if its a hardware problem why would it play a blu ray like batman begins ( a much bigger film in all ways including over 30gb ) and struggle with 2 older movies which are much smaller in size?

[Adbear]

It can be to do with bitrate and codecs

[dmemphis]

hmmmm so its more down to the way the blu ray disc has been made/packaged which makes it play ok or not? so because one plays ok it doesn't mean others will? could it also be the fact the mac mini has only got 1gb ram installed? would 2gb ram be better?

[Adbear]

You have to bear in mind that Blu-ray's can use 3 different Video codecs and a few different audio codecs, and they can have a bitrate up into the 40mbits range. Unless you have a graphics card that the system can offload on to then your cpu is on the lowend range.
The RAM isn't the problem, it's the CPU that's to low to play high bitrate stuff, and the MAC mini probably doesn't offload onto the GPU like you can on a PC

[dmemphis]

The graphics card is Intel GMA950 graphics processor with 64MB of DDR2 SDRAM shared with main memory1, memory is 1GB of 667MHz DDR2 SDRAM (PC2-5300), supports up to 2GB, is there a program work around i can use or i'm i screwed cos you can't upgrade the mini's on board graphics card! or is there an external usb graphics card i could get?
by the way thanks for all your help!

[Adbear]

There's no real workaround apart from re-encoding the video to a bitrate it can handle. With such a low spec graphics card and a low end CPU there's not much you can do

[3r1c]

Core 2 duo is definately powerful enough to play any blu-ray.
I do not know anything about macs, but on windows this cpu is very powerful.
The graphics card does not really matter, since your cpu will be doing all of the work anyway.

Playing from external drive may be a problem with high bitrates.
If the drive cannot transfer fast enough over usb or whatever you are using.

On windows i would tell you to use resource monitor to find where the bottleneck is, im sure mac has something similar where you can view the cpu/memory/disk speed use.

[Adbear]

Like I already said I use a 2.16 C2D and it doesn't play high bitrate Blu-ray files unless it can offload onto the GPU. If I use a graphics card that it can't offload onto then on peak bitrates it stutters. Not all C2D's are powerful enough to play back Blu-ray smoothly, I've found in extensive testing over the past year or so (I'm a system builder) that the minimum C2D you can get away with and expect to play back all Blu-ray without a GPU to offload on to is a 2.4. Anything less than that and you'll need a GPU which the Macmini doesn't have.
Unless his USB is USB 1 then that shouldn't be causing a problem as the highest a Blu-ray should go is around the 54Mbps unless it's playing PiP then it could double, but even then that only comes out at around 13.5MBps and single stream around 6.75MBps so there should be no problems from the USB drive.

If there's any way to watch the CPU usage whlst it's playing I'd try that so you can see if it peaks when it stutters

[dmemphis]

Hi,
to be honest i'm brand new to macs myself, only bought it cos it really is a great media player, very small, very quiet goes well under the telly etc etc, it does out put hd at 1920 x 1080p so thought i'd be ok? will try some how to check the cpu while playing, is there any video codecs/audio ( that you mentioned ) i can download to maybe help this issue? like i said i've only tryed 3 blu rays so for and one it played fine!
Thankyou very much for all your time and effort and skill on this matter!
Rob...

[Adbear]

I've never used one myself so wouldn't know, but I doubt there's anything you can do as it already appears to have the VC-1 codec installed

[Phrehdd]

Hi Rob,

I have been playing with Plex as well.

First - Plex is more a software solution. In turn it is also CPU not GPU intensive. It, at least for now, cannot take advantage of what higher end video cards can provide.

Second - As pointed out, blu ray movies are not all equal and some peak up to 40mb. This means that in some parts of the movies only a small amount of data is processed and in other areas, might be 40mb processed for the same amount of time on screen. Here is where the CPU can get into problems. This is inherent.

Third - Plex will play your DVDs properly with no effort. Blu Ray backup/archive files are a mixed bag and will remain as such with Plex on a Mac Mini.

There are 'other' forums on other sites that have discussed this.

Plex recently has an update that helps a bit with this problem for H.264 files. Meanwhile, some of us are waiting until mid-late November to see if a new Mac Mini comes out with better specs.

What you should do is play your files, and when they start to play use your keyboard and press "i" key. You will get an overlay of information. Two areas to look at - the values related to bitrates and dropped frames. Don't let drop frames get you upset. This happens even with regular blu ray players. Do worry if you are getting a lot at once. The second area is the CPU usage. This is misleading. CPU may show 120%. This should be 120% of BOTH processors working.
Also, you can end up with a respectable percentage like 120% yet problems. The issue is that this is real time driven. I am not the best at explaining this but I'll give you a working model approach. The processor can only process so much at any given time. A 5 second portion of movie is played real time for 5 seconds. The processor in turn has to get it all together as the movie is advanced so, here we are with some bitrate "peaks" that get processed but not very well. The processor never gets to that "200%" (or maxed out) because it is not on to processing the next part of the movie.

I have used Plex on an iMac 20" 2ghrz with some good success. I have also tried it on a Mac Pro Quad 2.66. Right away, less dropped frames and fairly unblemished playback. While it may be overkill the Mac Pro, it demonstrates that there is a correlation to the "power" of the processors and I would guess a great deal to do with the L Cache associated with the processor.

A nice example of saturation poor ability to process is the "Disneyland" image front to some of their movies. They are high bitrate. Pirates of The Caribbean comes to mind. Some folks have issues playing that yet, most of the movie plays relatively ok (save for a moment here and there).

You do* have the option to use Ripbot and if it works (not always as is) it can compress your movie down and the bitrates respectively seem lower.
I don't like this approach as I do* see the difference but others are okay with it.

Just a thought

- Phrehdd

[Phrehdd]

Like I already said I use a 2.16 C2D and it doesn't play high bitrate Blu-ray files unless it can offload onto the GPU. If I use a graphics card that it can't offload onto then on peak bitrates it stutters. Not all C2D's are powerful enough to play back Blu-ray smoothly, I've found in extensive testing over the past year or so (I'm a system builder) that the minimum C2D you can get away with and expect to play back all Blu-ray without a GPU to offload on to is a 2.4. Anything less than that and you'll need a GPU which the Macmini doesn't have.
Unless his USB is USB 1 then that shouldn't be causing a problem as the highest a Blu-ray should go is around the 54Mbps unless it's playing PiP then it could double, but even then that only comes out at around 13.5MBps and single stream around 6.75MBps so there should be no problems from the USB drive.

If there's any way to watch the CPU usage whlst it's playing I'd try that so you can see if it peaks when it stutters

I am not an expert but based on reading a bit about Plex (and playing with it) that your logic is correct but doesn't apply to Plex. Plex is CPU intensive and doesn't offload to GPU. Only real requirement of the Vid is having OpenGL present. (This is for the Mac).

While you might find this curious, it does allow for flexibility in software writing and exploiting various caching schemes without a great deal of programming. I believe the underpinnings for Plex is ffdshow or however it is spelled and its a fast and easy way to get up and running. Your point appears valid about GPU and the implied value of this type of scenario.

For those interesting in Plex some things to consider

1080p files - use the Mac Mini with 2ghrz not 1.83.
- Ram should be min 2 gigs, better is 2x2gig for 3.1 gig used.
(the mobo can only use 3.1 gigs of the 4 installed kinda like
Windows XP etc.)
- Read the Plex forums on their site. There are directly avialable
cache adjustments you can do.
- an overlooked item: turn off some resources such as spotlight
that draw from the CPU. (in a sense, when Plex runs dedicate
all available CPU power.)

If you are playing 720P and lower movies, the Mac Mini with Plex is really outstanding. For 1080p it plays some M2TS files and MKV etc with no problems and you get DTS or AC3 playback. The challenge remains with the fact Plex uses CPU in a real time way which is the inherent problem. I have played movies from both the local drive and via a NAS. Local plays a little better than from the NAS. I admit I have not tried an external drive via USB 2.0. My guess is that firewire is a better choice in this case but without testing, I can't say thats anything more than a hunch.

For those on the Windows side, Plex is derivative of XMBC. XMBC works on Windows though not as "fancy" an interface. What it can do is play DVD file structure with Vobs in original format and menus. M2TS files (sorry no blu ray structure), and other file formats including MKV. I honestly thing both Plex and XMBC, even with the inherent issues of underpinnings, is a far nicer front end than Windows Media Player. Perhaps later, they will add more directly TV tuner and PVR support. (Though you can work them along side other apps that do* offer those items etc.)

- Phrehdd