streamtools/testpcmtodump.lua

   1 infile, err = io.open(arg[1], "r");
   2 if not infile then
   3         error("Can't open input file: " .. err);
   4 end
   5
   6 outfile, err = io.open(arg[2], "w");
   7 if not outfile then
   8         error("Can't open output file: " .. err);
   9 end
  10
  11 is_high = false;
  12 last_trans_time = 0;
  13 samplenum = 0;
  14
  15 emit_transition = function(time, tohigh)
  16         x = time - last_trans_time;
  17         s = "";
  18         while x >= 4294967295 do
  19                 print("Skipping time ahead");
  20                 s = s .. string.char(255, 255, 255, 255);
  21                 x = x - 4294967295;
  22                 last_trans_time = last_trans_time + 4294967295;
  23         end
  24
  25         x4 = x % 256;
  26         x = (x - x4) / 256;
  27         x3 = x % 256;
  28         x = (x - x3) / 256;
  29         x2 = x % 256;
  30         x = (x - x2) / 256;
  31         x1 = x % 256;
  32
  33
  34         if is_high ~= tohigh then
  35                 s = s .. string.char(x1, x2, x3, x4);
  36                 if is_high then
  37                         s = s .. string.char(255, 255, 255, 255);
  38                 else
  39                         s = s .. string.char(0, 0, 0, 0);
  40                 end
  41                 if tohigh then
  42                         s = s .. string.char(0, 0, 0, 0, 255, 255, 255, 255);
  43                 else
  44                         s = s .. string.char(0, 0, 0, 0, 0, 0, 0, 0);
  45                 end
  46                 last_trans_time = time;
  47         end
  48         outfile:write(s);
  49         is_high = tohigh;
  50 end
  51
  52 emit_transition(0, false);
  53
  54 while true do
  55         inb = infile:read(1);
  56         if not inb then
  57                 break;
  58         end
  59         scaled = math.floor(50 * string.byte(inb) / 255 + 0.5);
  60         if scaled == 0 and is_high then
  61                 emit_transition(50000 * samplenum, false);
  62         elseif scaled == 0 then
  63                 -- Do nothing.
  64                 x = 6;
  65         else
  66                 if not is_high then
  67                         emit_transition(50000 * samplenum, true);
  68                 end
  69                 if scaled < 50 then
  70                         emit_transition(50000 * samplenum + 1000 * scaled, false);
  71                 end
  72         end
  73
  74         samplenum = samplenum + 1;
  75 end