[PD-dev] sound + video : real time issues

[Vilson Vieira]

Hans, thank you! We will try that.

2011/11/14 Hans-Christoph Steiner <hans at at.or.at>

>
> from the cmd line: -rt hig priority, -nrt low.
>
> .hc
>
> On Nov 14, 2011, at 9:44 AM, Vilson Vieira wrote:
>
> How to set high priority for audio Pd instance and lower priority to the
> other instance?
>
> All the best.
>
> 2011/11/14 Ricardo Fabbri <rfabbri at gmail.com>
>
>> Thanks for the replies.
>>
>> problems solved by using 2 Pd instances, one for video, the other for
>> audio, communicating via OSC on the same machine (or even different
>> machines). The machine also had to have a better CPU as doing this on a
>> slower dualcore laptop only fixed the audio, while the video got very slow.
>>
>> best,
>>
>>
>> On Monday, November 14, 2011, Hans-Christoph Steiner <hans at at.or.at>
>> wrote:
>> >
>> > I think generally, for gem + audio patches, people run two instances of
>> Pd, one for Gem and the other for the audio.  The audio instance has
>> realtime priority, and the Gem one does not.
>> >
>> > .hc
>> >
>> > On Nov 13, 2011, at 10:17 PM, Ricardo Fabbri wrote:
>> >
>> >> Hi,
>> >>
>> >> I am building instalations/instruments which control sounds
>> >> through the webcam, using a color detector that I submitted to this
>> >> list a couple of days ago. Things work well, and I am just facing real
>> >> time/delay issues now.
>> >> When I try to generate sound with any pix
>> >> processing, I am getting jumps in the sound (like on/off sounds at
>> >> about 5-20Hz). Turning off any pix processing, the sound is then back
>> >> to normal, even if I show the raw video from the camera on a gemwin.
>> >> By pix processing I mean anything with even only 1 pass through the
>> >> image on the CPU. I am using a ps3eye camera, which makes things
>> >> better as it has a high framerate, but I still get interruptions in
>> >> the sound.
>> >>
>> >> Why is this lag in the sound? The image with the output of the pix
>> >> processing doesn't seem to be moving any slower with or without sound.
>> >>
>> >> What are your experiences in trying to get gem pix processing, video,
>> >> and DSP to work in real time? My application is interactive, so that I
>> >> really need the sound to be as smooth as possible. Here are some
>> >> factors I will investigate, let me know if they make any sense to you:
>> >>
>> >> - It could be just too much data, even a single pass on each pixel
>> >> could be causing delays/jumps. I could downsample the image prior to
>> >> any pix processing
>> >> - The kernel is too slow in processing the video stream; I tried '-rt'
>> >> with no success
>> >> - Perhaps there is a problem in Pd sound scheduling vs pix processing
>> >> - Perhaps its just the CPU. In fact, I used OSC to do the video on one
>> >> machine, send the parameters to a second machine which then processes
>> >> the audio there. This effectively solved the problem. Question is, is
>> >> this due to CPU or to another factor?
>> >>
>> >> I would really appreciate hearing ideas from you, as I am new to this.
>> >> Best,
>> >> Ricardo Fabbri
>> >> --
>> >> Linux registered user #175401
>> >> www.lems.brown.edu/~rfabbri <http://www.lems.brown.edu/%7Erfabbri>
>> >> labmacambira.sf.net
>> >>
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>> >
>> >
>> >
>> >
>> ----------------------------------------------------------------------------
>> >
>> > Computer science is no more related to the computer than astronomy is
>> related to the telescope.      -Edsger Dykstra
>> >
>> >
>> >
>>
>> --
>>
>> Ricardo Fabbri
>> --
>> Linux registered user #175401
>> www.lems.brown.edu/~rfabbri <http://www.lems.brown.edu/%7Erfabbri>
>> labmacambira.sf.net
>>
>>
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>>
>
>
> --
> Vilson Vieira
>
> vilson at void.cc
>
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-- 
Vilson Vieira

vilson at void.cc

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