Hey all,
I'll try and work on some test patches, right now I'm trying hard to get an installation ready, and these issues turned out to be a large stumbling block.
I suppose I'm doing lots of processing that may be unusual, like:
Grab an image from video device put the image in a buffer for each frame send the image in the buffer to a second buffer on each bang from a metro. pix_share the image in the second buffer send a bang to tell second pd instance to pix_dump. turn off the metro. pix_dump (640x480 GRAY) to ann_som in a second thread netreceive the winning BMU use that BMU as the index in which the image has saved in a third buffer. turn the metro back on.
I'm not thinking pix_share should do sync!! But I feel the need for some infrastructure better than trigger for complex timing problems like those I'm having.
I'm still debugging my patch, but adding a whole lot of arbitrary delays (150ms) are being used to get PD to wait a little bit before accessing the image in a buffer once it has been written.
Seems the safest way...
I remember Cyrille did mention needing to use these delays to make things work. I had to use them in parts of pixelTANGO also (when a message gets passed through many objects and many routes it takes time...)
As I have not noticed any render blocks with pix_buffer stuff, can I assume it uses a thread like pix_image and so on? I think a "done" bang would be really useful there.
I also had issues with things like pix_histo, where I would try and save the hist, but the hist had not changed for the new pix_buffer_read frame, just because the delay was slower than t b b delay.
Are cyrille and I the only ones seeing these kinds of issues?
Thanks for the comments. .b.
chris clepper wrote:
Internally, objects like pix_image and pix_film set flags for whether an image is new or not. This tells other objects to update. Perhaps a generic object (pix_info ?) can output when that flag is set.
pix_share is a little different than image loading as it just dumps a new image into the gemlist each frame. It is not designed to do sync between instances of pd, but rather to be an asynchronous way to distribute processing. Making it sync would remove the performance gains.
On Thu, Oct 30, 2008 at 9:32 AM, Hans-Christoph Steiner <hans@eds.org mailto:hans@eds.org> wrote:
I agree. I think for any indeterminate operation, like anything in a separate thread, there should be a bang when that operation is complete. That way you can guarantee that things are ready when you run a process. If you want to make sure that things will be there on time, then these threaded/indeterminate operations should run well in advance. Using guesswork and delays is not a real solution... .hc On Oct 30, 2008, at 4:25 AM, cyrille henry wrote: > helo, > > i'm also having this kind of problem. > specially when loading a picture in pix_image. > i think the best would be the have a bang when things are ready... > > C > > > B. Bogart a écrit : >> Hey all, >> >> I'm having more and more problems with sync in PD. By sync I mean >> that >> parts of my patches have processing delays that mess up timing. In >> general I've been using buffers and delays to keep things working. >> >> This approach is not very scalable. >> >> I find myself using the "timer" object all the time to see if >> there is a >> processing delay I have to worry about. That is in cases where >> there is >> a bang saying an operation is done. >> >> Two examples I'm working on now (in Gem): >> >> First there is a delay between sending a message and the >> pix_buffer to >> store, and then again for pix_buffer_read to read the pixels. The >> delay >> is long enough that trigger does not work, there needs to be a >> delay to >> make sure the image in the buffer is the right one. (sometimes as >> much >> as 200ms) >> >> A second example is that I'm using pix_share and and second PD >> instance >> to offload some CPU usage. Making sure the image sent to that PD >> instance and the image received later in the chain is difficult. >> >> I'm not writing for specific advice, hence the generalities, but >> wanted >> to start a discussion on the issue. >> >> What is the long-term solution for PD to solve these issues? >> Should all >> objects that introduce a delay send a bang when they are complete? >> (for >> example pix_buffer? Of course an additional delay occurs when when >> the >> pix_buffer is written to memory and when it gets to the gfx card for >> display. >> >> I'm banging my head over these issues a lot lately and wonder if >> there >> is a better approach. >> >> Back to attempting kludging a solution. >> .b. >> >> >> _______________________________________________ >> GEM-dev mailing list >> GEM-dev@iem.at <mailto:GEM-dev@iem.at> >> http://lists.puredata.info/listinfo/gem-dev >> > > > _______________________________________________ > GEM-dev mailing list > GEM-dev@iem.at <mailto:GEM-dev@iem.at> > http://lists.puredata.info/listinfo/gem-dev ------------------------------------------------------------------------ ---- ¡El pueblo unido jamás será vencido! _______________________________________________ GEM-dev mailing list GEM-dev@iem.at <mailto:GEM-dev@iem.at> http://lists.puredata.info/listinfo/gem-dev