A suggestion from Johannes Taelman solved the issue:
"Make sure the number of audio samples used per scanline is a whole number."
Thanks for having a look in any case!
Derek
On 25/08/2018 20.44, Derek Holzer wrote:
Dear Pd folks,
I've written about this before here, and I still have not found a
solution. I've been chasing the same bug in my Vector Synthesis code for
a year now. The purpose of this code is to draw a "video raster" on an
X/Y oscilloscope screen with audio signals from a DC coupled MOTU audio
interface. The brightness of this raster will be modulated by
information from [pix_data]. Because I am redrawing the raster from
scratch and the pix information is not tied to the video frame/line rate
at all, this raster can be of arbitrary frame rate and line numbers
which remain within audio range. This part works fine and I have no
questions about that.
My problem is with creating the raster. No matter how I create my raster
signals, I get the same phase-related offset on my horizontal lines. The
amount of offset is dependent on the relationship between the vertical
and horizontal rate. You can see this in the video linked at the bottom
of this email. Please view that before posting any replies.
The Pure Data patch I am using, which includes three different equally
flawed methods of making this raster, is available at:
http://macumbista.net/wp-content/uploads/2018/08/oscilloscope-raster-test.txt
(Change .txt extension to .pd)
Video demo is here:
https://vimeo.com/286687337/0b865bd76c
I'm guess there is something in the DSP that I have overlooked. I'm also
guessing it will take some kind of guru to work it out. If you think you
are that guru, please let me know.
Thank you for your kind attention,
Derek
--
derek holzer
noise.art.technology
http://macumbista.net
_______________________________________________
Pd-list@lists.iem.at mailing list
UNSUBSCRIBE and account-management ->
https://lists.puredata.info/listinfo/pd-list
