oh, i thought the pbo message was to use a specific pbo Id.
since it's how many PBO to use, on a specific pix_texture or pix_snap, then my
question was irrelevant.
ok for the ring buffer:
possible latency vs possible performance gain, and computer specific tuning.
i'll try that as soon as i can.
thx
c
Le 29/02/2012 12:18, IOhannes m zmoelnig a écrit :
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On 2012-02-29 10:52, Cyrille Henry wrote:
Le 29/02/2012 09:34, IOhannes m zmoelnig a écrit :
and both [pix_texture] and [pix_snap] allow for asynchronous
DMA-transfers already (though i only added PBO-tarnsfers to [pix_snap] a
week ago or so).
it's not really documented anywhere (yet), but you can send a [pbo $1(
message to both these objects to specify the number of PBOs to use (with
"0" being the default behaviour)
Do you mean that since last week pix_snap should be lot's faster than it
use to be?
the default behaviour is still the same (pbo==0)
this is mainly because i found that the optimal setting varies greatly
from machine to machine.
e.g. on my netbook with fglrx drivers, the old non-pbo method is somehow
faster...
on my desktop (with some old nvidia card), using PBOs is faster.
i'd like to understand a bit more the use of single / multiple PBO :
what happens if 2 pix_video / pix_texture use the same PBO : will it be
slower than using 2 different PBO? (since 2nd pix_texture have to wait
for the PBO to be free in order to use it)???
each [pix_texture] will use their own set of PBOs.
when using more PBOs, you basically get a ring-buffer: while the current
image is uploaded using PBO(n), PBO(n-1) is displayed, so the upload has
one frametick to complete.
it also means, you get a delay when using>1 PBOs.
i haven't done any benchmarking with multiple image-sources (though the
PBO support for [pix_texture] was implemented in order to get reasonable
speed when displaying multiple hires videos for an installation)
same question with a pix_video / pix_texture and a pix_snap : is using 2
PBO lot's faster than using the same PBO (default behaviour)?
just try it :-)
fgmasdr
IOhannes
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