https://forum.cockos.com/showthread.php?t=143443

multichannel dB display tools

font_size = 16;
font_name = "Verdana";

buffer = 10000;

function get_samples_at_cursor(take)
(
  take_pcm_source = GetMediaItemTake_Source(take);
  //GetMediaSourceType(take_pcm_source, #typebuf);
  sample_rate = GetMediaSourceSampleRate(take_pcm_source);
  num_channels = GetMediaSourceNumChannels(take_pcm_source);
  samples_per_channel = 1;
  offs = GetPlayPosition() - item_pos;

  take != last_take ? (
    take_pcm_source = GetMediaItemTake_Source(take);
    //GetMediaSourceType(take_pcm_source, #typebuf);
    sample_rate = GetMediaSourceSampleRate(take_pcm_source);
    num_channels = GetMediaSourceNumChannels(take_pcm_source);
    last_accessor > 0 ? DestroyAudioAccessor(last_accessor);
    last_accessor = CreateTakeAudioAccessor(take);
    last_offs = -100000000.0;
    last_take = take;   
  );

  AudioAccessorValidateState(last_accessor) || offs != last_offs ? (
    memset(buffer, 0, samples_per_channel*num_channels);
    nsret = last_accessor > 0 ? (GetAudioAccessorSamples(last_accessor,sample_rate,num_channels,offs,samples_per_channel,buffer) > 0 ? samples_per_channel : 0) : 0;
    i = 0;
    nsret > 0 ? (
      chan = 50;
      loop( num_channels,
        chan[i] = 20 * log10(abs(buffer[i]));
        i = i + 1;
      );
    );
    last_offs=offs;
  );
);

function get_take()
(
  (item = GetSelectedMediaItem(0, 0)) ? (
    item_pos = GetMediaItemInfo_Value(item, "D_POSITION");
    (take = GetActiveTake(item)) ? (
      get_samples_at_cursor(take);
    );
  );
);

function init(window_w, window_h)
(
  //gfx_a = 1; gfx_r = 1; gfx_g = 1; gfx_b = 1;
  gfx_init("dB display", window_w, window_h);
  gfx_setfont(1, font_name, font_size);
);

function run() local(time_range, time_sel_start, time_sel_end)
(
  gfx_a = 0.5; gfx_r = 1; gfx_g = 1; gfx_b = 1;
  gfx_x = 10;
  gfx_y = 10;

  get_take();
  z = 0;
  maximum = 0;
  loop(num_channels,
    gfx_a = 0.5;
    gfx_x = 10;
    gfx_y += gfx_texth;
    gfx_printf("chan ");
    gfx_printf("%d", z + 1);
    gfx_a = 1;
    gfx_printf("  ");
    gfx_printf("%f", chan[z]);
    z = z + 1;
    maximum = max(maximum, abs(chan[z]));
  );
  
  gfx_a = 0.5;
  gfx_x = 10;
  gfx_y += gfx_texth * 2 ;
  gfx_printf("Maximum  ");
  gfx_a = 1;
  gfx_printf("%f", - maximum);
  
  gfx_update();
  gfx_getchar() >= 0 ? defer("run();");
);

// init(window_w, window_h);
init(220, 180);
run();