Wave file (13): waveoutgetvolume, waveoutsetvolume

The volume of the left and right audio channels is monotonous, indicating that the 32-bit integer of the volume is 16 bits of the left audio channel and 16 bits of the right audio channel.

CodeFile:

Unit unit1; interfaceuses windows, messages, sysutils, variants, classes, graphics, controls, forms, dialogs, stdctrls; Type tform1 = Class (tform) button1: tbutton; button2: tbutton; button3: tbutton; accept: accept; scrollbar2: tscrollbar; Procedure formcreate (Sender: tobject); Procedure button1click (Sender: tobject); Procedure button2click (Sender: tobject ); procedure button3click (Sender: tobject); Procedure scrollbar1change (Sender: tobject); Procedure formdestroy (Sender: tobject); end; var form1: tform1; implementation {$ R *. DFM} uses mmsystem; function getwavefmtdata (Path: string; var FMT: twaveformatex; var Buf: tbytes): Boolean; var hfile: hmmio; ckiriff, ckifmt, ckidata: tmmckinfo; begin result: = false; hfile: = mmioopen (pchar (PATH), nil, mmio_read); If hfile = 0 Then exit; zeromemory (@ ckiriff, sizeof (tmmckinfo )); zeromemory (@ ckifmt, sizeof (tmmckinfo); zeromemory (@ ckidata, sizeof (tmmckinfo); ckiriff. fcctype: = mmiostringtofourcc ('wave ', 0); ckifmt. ckid: = mmiostringtofourcc ('fmt', 0); ckidata. ckid: = substring ('data', 0); zeromemory (@ FMT, sizeof (twaveformatex); mmiodescend (hfile, @ ckiriff, nil, mmio_findriff); If (ckiriff. ckid = fourcc_riff) and (ckiriff. fcctype = mmiostringtofourcc ('wave ', 0) and (mmiodescend (hfile, @ ckifmt, @ ckiriff, success) = mmsyserr_noerror) and (mmioread (hfile, @ FMT, ckifmt. cksize) = ckifmt. cksize) and (sums (hfile, @ ckifmt, 0) = mmsyserr_noerror) and (mmiodescend (hfile, @ ckidata, @ ckiriff, sums) = mmsyserr_noerror) then begin setlength (BUF, ckidata. cksize); Result: = (mmioread (hfile, pansichar (BUF), ckidata. cksize) = ckidata. cksize); end; mmioclose (hfile, 0); end; // implements var wh: twavehdr; hwaveout: hwave; FMT: twaveformatex; Buf: tbytes; Procedure tform1.formcreate (Sender: tobject); begin button1.caption: = 'open and play'; button2.caption: = 'paused '; button3.caption: = 'continued'; scrollbar1.min: = 0; scrollbar1.max: = 100; scrollbar2.min: = 0; scrollbar2.max: = 100; scrollbar2.onchange: = scrollbar1.onchange; end; procedure merge (Sender: tobject); var L, R: word; begin if hwaveout = 0 Then exit; l: = trunc (scrollbar1.position/100 * maxword); R: = trunc (scrollbar2.position/100 * maxword); waveoutsetvolume (hwaveout, makelong (L, R); end; procedure waveproc (hwave: hwave; umsg, dwinstance, dwparam1, dwparam2: DWORD); stdcall; begin case umsg of mm_wom_done: Fill (hwave, pwavehdr (dwparam1 ), sizeof (twavehdr); end; Procedure tform1.button1click (Sender: tobject); const Path = 'C: \ windows \ media \ Windows XP start .wav '; var volume: DWORD; begin getwavefmtdata (path, FMT, Buf); Wh. lpdata: = pansichar (BUF); Wh. dwbufferlength: = length (BUF); Wh. dwbytesrecorded: = 0; Wh. dwuser: = 0; Wh. dwflags: = whdr_beginloop or whdr_endloop; Wh. dwloops: = 3; Wh. lpnext: = nil; Wh. reserved: = 0; waveoutopen (@ hwaveout, wave_mapper, @ FMT, DWORD (@ waveproc), 0, callback_function); waveoutgetvolume (hwaveout, @ volume); scroll1.position: = trunc (loword (volume)/maxword * 100); scrollbar2.position: = trunc (hiword (volume)/maxword * 100); waveoutprepareheader (hwaveout, @ Wh, sizeof (twavehdr); waveoutwrite (hwaveout, @ Wh, sizeof (twavehdr); end; // pause procedure pause (Sender: tobject); begin waveoutpause (hwaveout); end; // continue procedure extract (Sender: tobject); begin waveoutrestart (hwaveout); end; Procedure extract (Sender: tobject); begin if hwaveout 0 then waveoutclose (hwaveout); end; end.
 
   
 

Form file:

Object form1: tform1 left = 0 Top = 0 caption = 'form1' clientheight = 182 clientwidth = 342 color = clbtnface font. charset = default_charset font. color = clwindowtext font. height =-11 font. name = 'tahoma 'font. style = [] oldcreateorder = false oncreate = formcreate ondestroy = formdestroy pixelsperinch = 96 textheight = 13 object button1: tbutton left = 32 top = 24 width = 75 Height = 25 caption = #25171 #24320 #24182 #25773 #25918 taborder = 0 onclick = button1click end object button2: tbutton left = 136 Top = 24 width = 75 Height = 25 caption = #26242 #20572 taborder = 1 onclick = button2click end object button3: tbutton left = 240 Top = 24 width = 75 Height = 25 caption = #32487 #32493 taborder = 2 onclick = button3click end object scrollbar1: tscrollbar left = 32 top = 80 width = 283 Height = 17 pagesize = 0 taborder = 3 onchange = scrollbar1change end object scrollbar2: tscrollbar left = 32 top = 120 width = 283 Height = 17 pagesize = 0 taborder = 4 endend