Can any Mac Pro play 4x streams of 1080p without lag?

Discussion in 'Mac Pro' started by TigerFX, Sep 4, 2007.

  1. TigerFX macrumors newbie

    Joined:
    Sep 4, 2007
    #1
    I really want to have a video wall type display. I have a mac pro with 4x DVI ports (I think they're two nVidia 7300GT's) but the problem is it lags really badly if I stretch a 1080p movie across four screens (each at a 1920x1200 resolution). This is on an Intel quad-core w/ 8GB of RAM. In addition, there's no way for Quicktime to play more than one movie in full screen on different screens at the same time - it doesn't let you. So I guess I'm in need of:

    - Software that will play full-screen movies on different monitors at the same time (or better yet, one big movie scaled across all four screens)
    - Hardware that can do this without lagging.

    Does anyone have any idea if this is even possible with a Mac Pro? The minimum 1080p specifications require the Intel Core 2 Duo on the Mac Mini, and 1GB of RAM. So one would think that with an 8-core Intel chip and at least 4GB of ram, this should, in theory, be possible. If any work needs to be offloaded to a video card, I can probably load it with four video cards. But I just don't know if any software is smart enough to utilizie that kind of processing power.

    I'm half-tempted to buy four mac mini's, but that would make things very hard to syncronize (like if I want matching videos playing on two screens at once, for example).

    Thanks for any replies :).

    --Allen
     
  2. StealthRider macrumors 65816

    StealthRider

    Joined:
    Jan 23, 2002
    Location:
    Yokosuka, Japan
    #2
    What's the data rate (in kb/s or mb/s) of the videos you're going to want to play?
     
  3. Wild-Bill macrumors 68030

    Wild-Bill

    Joined:
    Jan 10, 2007
    Location:
    bleep
    #3
    Hopefully MultiMedia will wander in here and provide a suitable answer. He's got multiple machines, multiple monitors.
     
  4. bennyboi macrumors regular

    bennyboi

    Joined:
    Jun 1, 2006
    Location:
    West Coast
    #4
    Data Rate

    Whatever the data rate is, it's probably too high for your hard disks to play them. Forget processor speed and RAM. You're good there. You're still limited to 7200 rpm disks (be it fw800 or internal SATA).
    You will most likely need a RAID setup. There are several options here - SATA , SCSI, etc. Visit MacGurus.com and do some research.
    That may provide the speed you need. Plus- quicktime alone has a hard time handling full res video. I suggest making one 1080 movie with the videos in each corner. Scale each video down to 25%, tile them in each corner. When you play them full screen, the data will be a little chopped, but it might still look half decent?
     
  5. StealthRider macrumors 65816

    StealthRider

    Joined:
    Jan 23, 2002
    Location:
    Yokosuka, Japan
    #5
    The limiting factor is definitely the data rate of the hard disks. Is each video less than 1.5GB in size? If so, you can try playing them once to cache them to RAM, and see if the frame rates increase. If not...I have no idea, besides what bennyboi said about RAIDing.
     
  6. Pressure macrumors 68040

    Pressure

    Joined:
    May 30, 2006
    Location:
    Denmark
    #6
    I suppose this is compressed High Definition 1080p and not uncompressed streams?

    If it is uncompressed it's a no go. You will need 120MB/s per stream then or 480MB/s altogether
     
  7. TigerFX thread starter macrumors newbie

    Joined:
    Sep 4, 2007
    #7
    Thanks for the replies,

    The video is compressed. I created a sample 1080p animation that was, if I recall correctly, only a couple of meg for this very animation which was about 10 seconds long. I'm using Apple's H.264.

    If it is compressed video, it's not a disk speed limitation, right? And even if it was, couldn't I offload some of them onto a Firewire 800 drive? That should be more than enough to stream in compressed HD.

    I gave that a shot. I scaled the Shrek 3 trailer (1080) so it was stretched across multiple monitors, and it began to lag very badly - only a few frames per second. This means to me that it's not a matter of reading off disk, or even decoding the compression, but a display limitation. The machine simply isn't updating that many millions of pixels that quickly.

    Is this something that you'd be able to off-load to a video card? I'd always assumed that was what the video card was for, but I've heard that Quicktime likes to use your CPU and not much of the GPU. The Mac Mini is a breathing example - it has no dedicated video card and the 2GHZ runs 1080p fine.

    Here's an idea: does anyone know if I can spawn four instances of Quicktime and assign each one to its own two cores on the processor? I've heard of Bare Feats doing that before. I think as it is now, clicking the Quicktime icon in the dock when Quicktime's running just opens the window you already have up, it doesn't spawn another process of itself. And the way Quicktime is built, it only plays audio from one window at a time. This is another thing which would be nice to have more control over; I don't know if spawning multiple instances would achieve that.

    Thanks so much,

    --Allen
     
  8. ZachPruckowski macrumors member

    Joined:
    Aug 15, 2007
    #8
    The disk speed limitation is the speed of the disk, not the interface. An average 7200rpm desktop drive might have speeds in the neighborhood of 40-60 MB/s of streaming read. This is greatly reduced when you're trying to do 4 streams at once. 1080p on HD-DVD and BR is roughly 6 MB/s. When you multiply that by 4 and factor in the added complexity of having 4 streams instead of 1 big one, you can see that you hit the limit of a simple HDD. You would have a lot better luck with either a RAID 1 (which would basically double that speed) or offloading two of the streams to a separate drive. Either a FW800 or internal SATA drive would be fine (and a FW 400 drive would probably also be useful, if FW800 is unavailable)

    Download VLC (videolan.org) and try it. I think VLC is partially GPU-driven.

    You could try making four copies of Quicktime Player, and naming the Quicktime Player1, Quicktime Player2, etc. For easy control of the 4 audio streams, consider shelling out for Audio Hijack Pro.
     
  9. doc james macrumors member

    Joined:
    May 3, 2007
    #9
    I've looked into this before (though I wasn't so adventurous with the resolution). This doesn't directly answer your question but VLC has some useful controls for video walls that I could only otherwise find in v. expensive software - number of screens to split over etc. Or you can easily run multiple instances of it. I was using a rusty PC with dual athlons at the time with a four headed matrox card (G200 - virtually no GPU). In short, try VLC.
     
  10. Cromulent macrumors 603

    Cromulent

    Joined:
    Oct 2, 2006
    Location:
    The Land of Hope and Glory
    #10
    No you wouldn't. All RAID 1 does is mirror two drives so if one crashes you have an exact copy. RAID 0 is the performance one, it stripes data across two or more drives and thus means it has two sets of heads to read data thus doubling the speed.



    VLC is probably your best bet. Quicktime player adds an unnecessary overhead I have found. VLC is much better suited to HD video if you ask me.
     
  11. twoodcc macrumors P6

    twoodcc

    Joined:
    Feb 3, 2005
    Location:
    Right side of wrong
  12. cokersa macrumors member

    Joined:
    Apr 13, 2007
    Location:
    Kansas City
    #12
    Neither statement is technically correct. It depends a lot on the way the RAID controller software is written, caching onboard the disks, whether the disk controller does look-ahead queuing, the distribution of the data on the disk platter (sequential or random), and the type of data you are pulling off the disk (small or large files).

    When accessing single large files that are sequentially located on the disk, its true that RAID 0 gives you about twice the data throughput of a RAID 1 configuration. However, that configuration happens rarely in today's multi-tasking systems. In small file, random access read (as opposed to write) situations, RAID 0 and RAID 1 actually perform comparably (since the limitation is movement of the disk arm in both cases, not the read speed of the disk head).

    If you are simultaneously trying to read four comparatively large files (large enough not to be cached), which aren't likely to be in the same location on the disk platters, then RAID 0 might perform better than RAID 1, but certainly not twice as well.
     
  13. hail2bfly macrumors newbie

    Joined:
    Sep 22, 2007
    #13
    Quicktime bug?

    Howdy yall
    I have a interesting bug that i was hoping u guys would know whats up.

    I'm using an Apple Powermac G5 Quad 2.5ghz
    with 1.5 gb pc4200 ram


    I have a hdv footage (filmed on Canon-XHA1) that i captured and edit through Final Cut Pro. No lag whatsoever.
    When i even export to selfcontained FCP movie file no lag when i played it through quicktime.

    (All settings were the same from capture to export, no change in codec/framerate/resolution/audio)


    BUT...lol....
    If i try to view the original capture footage of the HDV outside and without going through final cut, there's lag.....

    So my dilema is why my quicktime could handle HDV through final cut, but standalone it would lag?

    thanks
     
  14. drj434343 macrumors member

    drj434343

    Joined:
    Jan 11, 2006
    Location:
    Portland, OR
    #14
    another thought

    If the OP is saying he tries to span one compressed 1080p movie trailer across monitors, and still gets the lag, it seems like we could discount the hard drive throughput issue.

    I've had a bit of experience with multiple monitors, and it always seems like you get really diminished performance with video or windowed games when you ask it to span monitors. I think there might be some larger technical and performance issues when you ask one or two cards to produce the same image across monitors. I've seen this same issue on many occasions, spanning PC's and Mac's. Just a thought.
     

Share This Page