[PD] redraw array while recording into it

[Roman Haefeli]

On Tue, 2023-03-28 at 09:29 +0200, Simon Iten wrote:
> yeah, the workaround with array_set causes clicks in the recording

The visual representation of arrays whose number of samples exceeds the
number of visual pixels suffers from aliasing so that resulting visual
waveform looks pretty random sometimes. Another issue is that the
amount of data is pretty large in the table holding audio data, much
larger than what is necessary for a proper visual representation. This
lead me to create an abstraction [rh_wavedisplay] that translates
original audio data from a table to a smaller table that is only used
for visual representation. Because the display table is much smaller,
updating it is not so costly and it allows for neat tricks like zooming
and panning. Also, you can use it to update the display during the
recording to an audio table. See example in the link:

https://netpd.org/~roman/tmp/wavedisplay_example.zip  

The visual table has twice the points of its visual width in pixels so
that the minimum and maximum of the segment of audio data covered by
one display pixel is displayed. This creates a solid black waveforms
for audio data that would otherwise be displayed with weird aliasing.

Note: there is a bug where some peaks of the previous display are still
apparent in the updated display. If some brave person knows how to fix
this, that would be more than welcome.

Roman
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