Alternative distribution to optical disks : SSD, cards, and download*

Discussion in 'Console Technology' started by Cheezdoodles, May 26, 2008.

  1. DSoup

    DSoup meh
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    It's partly hardware; the PS4's hardware zlib decompression plays a role. I believe Xbox One has something similar?

     
  2. MrFox

    MrFox Deludedly Fantastic
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    http://www.vgleaks.com/world-exclusive-durangos-move-engines

    Not sure if there's a better source than vgleak... XB1 has a zlib decoder tied to DMA #2. So the hardware is certainly designed to do that job perfectly. It seems they didn't reserve that DMA for the OS, so background install cannot use it, then it would up to the game developers to implement background install? What if the game needs to use it for jpeg decoding while streaming data from the HDD?
    That's more than enough for both the bluray install and HDD streaming for the game, at the same time :wink:

    EDIT: Uh. Stupid me. Why would it need to decompress the data, it probably need only to copy from the disc to the HDD. It would only decompress when reading it for the game.
     
    #1942 MrFox, Jul 31, 2014
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  3. taisui

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    partial install play has little to do with zlib, quite certain that's not what Cerny's talking about either. It's being taken out of context.

    the files needs to organized in a certain way that a "partial" install allows the game to start while the rest of the files are copied over.
    A simpler way of looking at this is that all the files needed for the intro/menu/first level are copied first into the HDD, then it's signaled that the game is ready.
    this would likely to cause some work on the devs, and it probably need to be part of the certification process.
     
    #1943 taisui, Jul 31, 2014
    Last edited by a moderator: Aug 1, 2014
  4. DSoup

    DSoup meh
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    Of course it does. The 6x Blu-ray drives tops out at 27mb/sec and my PS4 games are between 6Gb (Lego Marvel Super Heroes) to 20-22Gb (KZ, BF3, AC4, WATCH_DOGS). If all you're installing from disc then that 27mb/sec needs to be heavily compressed to start with to be able to install enough to start playing.

    If it's not compressed than PlayGo will take that much longer before you can start playing. Is zlib critical for the software side of PlayGo? :nope: Does zlib make PlayGo and OS-managed background gradual installs better/faster? :yep2:
     
  5. taisui

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    You are missing the point.
    Boot up time is probably a certification requirement on the PS4 and not on the X1. :roll:

    So look at what Cerny said, "system will decode it on the fly"
    yea I am with MrFox on this one, the "on the fly" part is from the HDD to the RAM, and not from the BD to HDD.

    So, are you speculating, or you know for sure?
     
    #1945 taisui, Aug 1, 2014
    Last edited by a moderator: Aug 1, 2014
  6. TheWretched

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    I don't know if using zlib "isos" is as easy, since you can just "seek" to the sector you want. But I seem to remember that the PlayGo system uses a clustered system... so maybe they circumvent the problem that way and games need to take this into account? I dunno... I'd imagine that the games are "developer compressed" when installed (as to assure it loads fast and doesn't make problems).
     
  7. DSoup

    DSoup meh
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    What I quoted above, once more.

    Games are zlib compressed on media (Blu-ray).
     
  8. taisui

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    He didn't say it's inflated with the zlib hardware during installation from media to the HDD, which was what you were suggesting.
    The fact he said "on the fly" inflation suggest the contrary, meaning that they are still stored in a compressed form on the HDD.

    Also:
    So won't you put in your BDs and get a comparison on media size vs install size?
     
    #1948 taisui, Aug 1, 2014
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  9. DSoup

    DSoup meh
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    And where did I suggest this exactly? I said was at had Blu-ray drive speed of 27mb/sec that data would need to be heavily compressed.

    It's reading data off disc to fill RAM with enough assets to start playing the game. Only you MrFox were talking about the HDD.

    Cerny's explanation is clear to me, the goal of PlayGo is to get the game up and running as soon as it can and key to this is having the data compressed on the disc because even a 6x Blu-ray drive is slow. As PlayGo is reading off the Blu-ray it's not only copying that to the HDD, it's populating RAM as it would during a conventional load as per a HDD install. If a partially installed game needs data not yet on the HDD it pulls it right off the disc. Any spare time is spent copying the remainder off the disc until the game is fully installed.

    Sent from my iPhone using Forum Runner.
     
  10. taisui

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    Ok...so now it pulls off the BD directly into the RAM bypassing the HDD?
     
  11. Shifty Geezer

    Shifty Geezer uber-Troll!
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    Isn't that the same as optical disk based consoles since forever? Optical read has always been the slowest link and content has always been compressed for loading as decompressing is faster.

    It writes to RAM and HDD at the same time. That'd be the fastest way.
     
  12. DSoup

    DSoup meh
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    If a game has not completely installed, i.e. not everything on the Blu-ray disc has been copied to the HDD and the game needs something that's only on the disc then it's got to get that data from the disc, obviously. In this scenario the game will read the data from the Blu-ray and use it as it would were it read off the HDD, while PlayGo copies that same read data to the HDD.

    I don't understand your 'bypassing the HDD' point. Are you suggesting that PlayGo would only load data from the HDD? Which in the above scenario would result in a 1) a read-from-disc, 2) a write-to-HDD, 3) a read-from-HDD. Clearly less efficient than the first way which is one read and one write.

    Quoting Mr. Cerny once again:

    Yes, and no. This is the first generation of consoles where full installation to HDD is mandatory. On PlayStation 3 and Xbox 360 full installs were very rare and I can't think of any mainstream games that benefited from the PlayStation 2 Ethernet/HDD expansion. For most games in previous generations, the problem developers tackled was reading data off the disc as fast as possible to keep load times down.

    Prior to realtime zlib hardware decompression being standard, developers had to balance the variables of data decompression between disc I/O and CPU/RAM. Highly compressed data means faster disc I/O (reads) but then you have to decompress that data in RAM before you can use it. You need RAM for the compressed data read from disc, CPU time to decompress it and RAM for the target (uncompressed) data. If your game loads levels while the user looks at a loading screen then that's viable, but if you're in an open world game like GTA then maybe heavy compression isn't viable because of the hit to RAM (already tight) and CPU which is also running the game. You might need to dial it down the compression quite a bit or forgo it completely.

    Realtime hardware zlib decompression is significant because now developers can compress everything to hell and back and never worry this impacting reading the data off the drive.

    Yes, and given the crazy ass speed of installing/loading/playing PS4 games, that's what I strong believe happens.
     
    #1952 DSoup, Aug 2, 2014
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  13. -tkf-

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    On the Information page it says that Infamous is a 21GB download and the install size is 22GB
    I donĀ“t know how it counts that install size, if video, screenshots etc is included in that, i doubt it.
     
  14. Shifty Geezer

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    Files can take up more space on an HDD than their actual file size due to the fileformats using blocks of fixed sizes. The smallest block size is something like 4kb, so 10 1kb UI PNGs would take up 40k. If the average file overruns by half a block and you have 10,000 files, that's 20 Mbs. The large discrepency is possible just rounding errors? 20.4 GBs for download, 20.6 GBs for install.
     
  15. taisui

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    Oh...okay then...cause you are really just pulling 2 sentences from Cerny and combined into one of your own.

    Partial install has been done for a while before the PS4. if the game is chunked correctly. the source, whether download or physical media, doesn't matter, it works the same way. It's just software.
     
    #1955 taisui, Aug 2, 2014
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  16. -tkf-

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    When is this? Afaik the PS4 installs a game even if you are playing another game.. got to test that of course, but that was my impression.

    Even then, the games on the PS4 launch so fast that i doubt it would matter much.
     
  17. Brad Grenz

    Brad Grenz Philosopher & Poet
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    Actually, I think we've struck on one of the reasons PS4 initial loads and installs are faster than Xbox One. We heard pretty early on that games for Xbox One required full installation to the hard drive and nothing could be run or copied to memory directly from the optical drive. I believe, in concept, the GameOS is literally not aware that an optical drive is connected to the system at all. So to get a game running you have to copy enough of the installation to the hard drive, and then you have to read everything you've been writing again to get it loaded into memory. The PS4 solution is more flexible in that it fills memory at the same time as it writes to disc and prioritizes the running game's data demands over the background hard drive install. Xbox One can't do the same because every file has to be on the hard drive first.
     
  18. DSoup

    DSoup meh
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    I don't understand this :???: Cerny's interview contains multiple sentences. My post contains multiple sentences :???: Did I wander inadvertently wander into a forum for English for pendants?

    Nobody is arguing otherwise. What makes PlayGo different in the console space is that the data can be heavily compressed on the media and never needs to be unpacked for installation; that happens during load whether from Blu-ray disc or HDD.

    What I think Shifty means is that as the game is loaded (to RAM) it's copied to HDD. That is what Mark Cerny says is happening and I guess he ought to know!
     
  19. taisui

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    Malarkey...

    When PS4 "installs" a game, it does it in the OS, where it copies the chunks required to boot up into the HDD first. Once it's ready, the icon switch to "Start" when you can start the game [from the HDD] and in the background it keeps copying.

    If it was able to load straight it to the RAM AND copy to the HDD concurrently, then why would you need to even wait for it to install in the OS first? It ought to just allow you to "Start" immediately upon inserting the BD, with the zlib voodoo doing all the work.
     
  20. DSoup

    DSoup meh
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    Preliminary install aside - this was discussed earlier. Search for the discussion on "40 seconds". Discussion then moved on to what happens after that.
     
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