Hello All:

(Cross posted to the wxperl-users mailing list)

Awhile back I was working on some wxPerl code to simulate an o-scope display screen. While the original requirement that started me down that path went away, I did get a proof of concept working that displayed several waveforms and a four channel logic analyser(animated). I have also been playing with the Gqrx software defined radio package and developed a wxPerl based Gqrx scanner application plug-in. A request was made on the Gqrx google group for a method to display the raw audio waveform. It sounded like a good challenge. Gqrx outputs one channel of 16-bit, 48KHz audio to a UDP port. I have this working with a scrolling audio waveform on the o-scope screen. I wonder, and it's hard to tell, if the display is keeping up with the 48KHz data stream. Am I dropping packets? Can I speed up the display process using a memory file rather than writing to a disk file? Will Wx support this? This is the current display and refresh code.

    # Create the Display(bmp & sbm) and Drawing(image) Objects
    #    Uses GD calls to draw the screen background and waveform on t
+he image object
    $self->{bmp} = Wx::Bitmap->new("rawaudio.png", wxBITMAP_TYPE_PNG);
    $self->{sbm} = Wx::StaticBitmap->new($self, wxID_ANY, $self->{bmp}
+, wxDefaultPosition, [600,600]);
    $oscope->{image} = GD::Image->new($oscope->{maxw}, $oscope->{maxh}
+) || die;

    # Read the updated image and refresh the display
    $self->{bmp} = Wx::Bitmap->new("rawaudio.png", wxBITMAP_TYPE_PNG);
+    # Reload the screen image
    $self->{sbm}->SetBitmap($self->{bmp});                # Refresh sc
+reen

    # Save the Drawing Object to a disk file
    my $png_data = $oscope->{image}->png;                # Write image
+ to a file
    open OUTFILE, ">", "rawaudio.png" || die;
    binmode OUTFILE;
    print OUTFILE $png_data;
    close OUTFILE;
[download]

Can this code be modified to use a memory file? Syntax? I am also considering moving the socket code into it's own thread to isolate the reading and decoding of the UDP packets from the updating of the display. Thanks in advance,

Update:

I now have a fairly functional raw audio display script. I still don't know if I am dropping any packets. I am considering developing a UDP server script to feed controlled waveform packets to my script to help to resolve this question. See jmlynesjr for a snapshot of the screen. I will post the code to CUFP later as another wxPerl example. It was a good learning experience for using and decoding/unpacking UDP packets, writing to memory files, and for reusing my simulated o-scope code. Dereferencing lists and arrays inside hashes gave me trouble and I may post a follow-up question after a little more reading on the topic.

James

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