[PD] how to expand time limit for video delay?

[IOhannes m zmölnig]

On 09/19/2015 04:41 PM, Arturo Moya Villén wrote:
> delay's lenght (1800 frames at this moment). In my imagination I can see a
> one year's delay. Even if I understand this is imposible rigth now, I would

i don't think that there is anything in Gem preventing you from doing that.

> like to find a way to, at least, expand this limit, but when I increase the
> number in pix_delay and I create the gem window Pd crashes.
> 
> I assumed this happened for a hardware limit, cause I was working with a
> not very powerful minimac (2.7 GHz Intel Core i7, 16 GB RAM, and a AMD
> Radeon HD 6630M 256 MB Graphic Card). But some days ago I bought a brand
> new Imac (Retina 5K, 27-imch, Mid 2015 with a 3,3 GHz Intel Core i5
> processor, 32 GB RAM and a AMD Radeon R9 M290 2048 MB Graphic Card) and I
> get an almost identical problem,(I arrived to 1850 lenght) so I feel a bit
> desperate and without a direction to explore. Does anybody knows the reason

there are two things you would need:
- enough memory to store 1 year of video frames stored at 20fps (or
whatever your fps is)
- an operating system that allows you to address that much memory.

a quick calculation should give you the amount of memory needed:
- the size of one frame depends on the resolution and colourspace you
are using; assuming full HD and RGBA, that makes:
 1920 * 1080 * 4 = 8294400 bytes
- to delay a video for one year, you will need to store a couple of rames:
  20fps * 60sec * 60min * 24h * 356d  = 615168000 frames

- which gives you a total of required bytes
 8294400 * 615168000 = 5102449459200000
if i managed to do without errors, thats about 4.6 Petabyte (or about
148500 times more memory than you currently have. so i dunno whether you
can cram that much memory in your brand new Imac; but Blue Waters¹ has
at least 1.5PB, so we are getting somewhere).

you can of course reduce the size a bit, e.g. by using greyscale images
instead of RGBA, which will reduce the required size to just a bit more
than 1.1PB;
or use less resolution.


the second requirement is easier to meet:
if you want to address more that 4GB of RAM, you need a 64bit OS *and*
the application (Pd/Gem) must be 64bit as well.
E.g. using a linux based system can do that easily².

fgmdsar
IOhannes



¹ https://en.wikipedia.org/wiki/Blue_Waters
² due to lack of manpower, the 64bit port of Gem on OSX still lacks
proper video capture. as for w32, i don't think anybody ever tried to
build Pd and/or Gem for w32/64bit.




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