Playing PCM Wav File in Delphi - delphi

Question

I have written a simple code that reads the header of a Wav File and then starts playing it. this is my code:
unit Unit1;
interface
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Generics.collections,
Vcl.ExtCtrls, MMSystem;
type
TForm1 = class(TForm)
Button1: TButton;
OpenDialog1: TOpenDialog;
Label1: TLabel;
Label2: TLabel;
Shape1: TShape;
Image1: TImage;
procedure Button1Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure FormClose(Sender: TObject; var Action: TCloseAction);
private
{ Private declarations }
public
{ Public declarations }
end;
type
TWaveformSample = integer; // signed 32-bit; -2147483648..2147483647
TWaveformSamples = packed array of TWaveformSample; // one channel
var
Form1: TForm1;
myWavFile: file;
DataBlock: array[0..3] of byte;
Count: integer;
NumOfChannels: integer;
SampleRate: integer;
BytesPerSecond: integer;
ByesPerSample: integer;
BitsPerSample: integer;
CompressionCode: integer;
CompressionDesc: string;
BlockAlign: integer;
ExtraFormatBytes: integer;
CompressionCodes: TDictionary<integer, string>;
BytesRead: integer;
Samples: TWaveformSamples;
fmt: TWaveFormatEx;
PacketIsPlaying: Boolean;
implementation
{$R *.dfm}
procedure InitAudioSys;
begin
with fmt do
begin
wFormatTag := WAVE_FORMAT_PCM;
nChannels := NumOfChannels;
nSamplesPerSec := SampleRate;
wBitsPerSample := BitsPerSample;
nAvgBytesPerSec := nChannels * nSamplesPerSec * wBitsPerSample div 8;
nBlockAlign := nChannels * wBitsPerSample div 8;
cbSize := 0;
end;
end;
procedure PlaySound;
var
wo: integer;
hdr: TWaveHdr;
begin
if Length(samples) = 0 then
begin
Writeln('Error: No audio has been created yet.');
Exit;
end;
if waveOutOpen(#wo, WAVE_MAPPER, #fmt, 0, 0, CALLBACK_NULL) = MMSYSERR_NOERROR then
try
PacketIsPlaying := True;
ZeroMemory(#hdr, sizeof(hdr));
with hdr do
begin
lpData := #samples[0];
dwBufferLength := fmt.nChannels * Length(Samples) * sizeof(TWaveformSample);
dwFlags := 0;
end;
waveOutPrepareHeader(wo, #hdr, sizeof(hdr));
waveOutWrite(wo, #hdr, sizeof(hdr));
//sleep(450);
//while waveOutUnprepareHeader(wo, #hdr, sizeof(hdr)) = WAVERR_STILLPLAYING do
//sleep(100);
finally
waveOutClose(wo);
PacketIsPlaying := False;
end;
end;
function ReadDataBlock(Size: integer): Boolean;
begin
try
BlockRead(myWavFile, DataBlock, Size, Count);
INC(BytesRead, Size);
Result := True;
except
Result := False;
end;
end;
function OpenWav(FileName: string): Boolean;
begin
try
Assignfile(myWavFile, filename);
Reset(myWavFile, 1);
Result := True;
except
Result := False;
end;
end;
function CloseWav: Boolean;
begin
try
CloseFile(myWavFile);
Result := True;
except
Result := False;
end;
end;
function ValidateWav: Boolean;
const
RIFF: array[0..3] of byte = (82, 73, 70, 70);
WAVE: array[0..3] of byte = (87, 65, 86, 69);
_FMT: array[0..3] of byte = (102, 109, 116, 32);
FACT: array[0..3] of byte = (102, 97, 99, 116);
DATA: array[0..3] of byte = (100, 97, 116, 97);
_DATA: array[0..3] of byte = (64, 61, 74, 61);
var
RiffChunkSize, FmtChunkSize, FactChunkSize, DataChunkSize, i, j, tmp, Freq: integer;
omega,
dt, t: double;
vol: double;
begin
BytesRead := 0;
//Check "RIFF"
ReadDataBlock(4);
if not CompareMem(#DataBlock, #RIFF, SizeOf(DataBlock)) then
begin
Result := False;
Exit;
end;
//Get "RIFF" Chunk Data Size
ReadDataBlock(4);
Move(DataBlock, RiffChunkSize, 4);
//Check "WAVE"
ReadDataBlock(4);
if not CompareMem(#DataBlock, #WAVE, SizeOf(DataBlock)) then
begin
Result := False;
Exit;
end;
{FMT ---------------------------------------------------------------------}
//Check "FMT"
ReadDataBlock(4);
if not CompareMem(#DataBlock, #_FMT, SizeOf(DataBlock)) then
begin
Result := False;
Exit;
end;
//Get "FMT" Chunk Data Size
ReadDataBlock(4);
Move(DataBlock, FmtChunkSize, 4);
BytesRead := 0;
//Get Wav Compression Code
ReadDataBlock(2);
Move(DataBlock, CompressionCode, 2);
if not CompressionCodes.TryGetValue(CompressionCode, CompressionDesc) then
CompressionDesc := 'File Error!';
//Get Number of Channels
ReadDataBlock(2);
Move(DataBlock, NumOfChannels, 2);
//Get Sample Rate
ReadDataBlock(4);
Move(DataBlock, SampleRate, 4);
//Get Average Bytes Per Second
ReadDataBlock(4);
Move(DataBlock, BytesPerSecond, 4);
//Get Block Align
ReadDataBlock(2);
Move(DataBlock, BlockAlign, 2);
//Get Bits Per Sample
ReadDataBlock(2);
Move(DataBlock, BitsPerSample, 2);
//Extra Format Bytes
if BytesRead <= FmtChunkSize - 2 then
begin
ReadDataBlock(2);
Move(DataBlock, ExtraFormatBytes, 2);
end;
//If it's not Uncompressed/PCM File, then we have Extra Format Bytes
if CompressionCode <> 1 then
begin
//Skip Compression Data
for i := 0 to FmtChunkSize - BytesRead - 1 do
ReadDataBlock(1);
Result := False;
Exit;
end;
{FACT --------------------------------------------------------------------}
{FactChunkSize := 0;
//Check "FACT"
ReadDataBlock(4);
if CompareMem(#DataBlock, #FACT, SizeOf(DataBlock)) then
begin
//Get "FMT" Chunk Data Size
ReadDataBlock(4);
Move(DataBlock, FactChunkSize, 4);
BytesRead := 0;
for i := 0 to FactChunkSize - BytesRead - 1 do
ReadDataBlock(1);
end; }
{DATA ------------------------------------------------------------------}
while BytesRead < FmtChunkSize do
ReadDataBlock(1);
BytesRead := 0;
//Skip bytes until "data" shows up
while (not CompareMem(#DataBlock, #DATA, SizeOf(DataBlock))) and (not CompareMem(#DataBlock, #_DATA, SizeOf(DataBlock))) do
begin
ReadDataBlock(4);
end;
ReadDataBlock(4);
Move(DataBlock, DataChunkSize, 4);
Form1.Label1.Caption := 'Compression Code: ' + IntToStr(CompressionCode) + #10#13 +
'Compression Description: ' + CompressionDesc + #10#13 +
'Number of Channels: ' + IntToStr(NumOfChannels) + #10#13 +
'Sample Rate: ' + IntToStr(SampleRate) + #10#13 +
'Byes per Sample: ' + IntToStr(ByesPerSample) + #10#13 +
'Byes per Second: ' + IntToStr(BytesPerSecond) + #10#13 +
'Bits per Second: ' + IntToStr(BitsPerSample);
tmp := FileSize(myWavFile) - DataChunkSize;
{ j := 0;
Form1.Image1.Canvas.Rectangle(0, 0, Form1.Image1.Width, Form1.Image1.Height);
for i := 0 to (DataChunkSize div 20) do
begin
//BlockRead(myWavFile, DataBlock, 76, Count);
tmp := tmp + 76;
Seek(myWavFile, tmp);
ReadDataBlock(4);
Move(DataBlock, Freq, 4);
if i mod ((DataChunkSize div 80) div Form1.Image1.Width) = 0 then
begin
INC(J);
Form1.Image1.Canvas.MoveTo(j, 121 div 2);
Form1.Image1.Canvas.LineTo(j, (121 div 2) - Trunc((Freq / High(Integer)) * (121 div 2)));
end;
Application.ProcessMessages;
end;
Seek(myWavFile, FileSize(myWavFile) - DataChunkSize); }
InitAudioSys;
PacketIsPlaying := False;
SetLength(Samples, fmt.nSamplesPerSec);
while PacketIsPlaying = false do
begin
for i := 0 to fmt.nSamplesPerSec do
begin
ReadDataBlock(4);
Move(DataBlock, Freq, 4);
Samples[i] := Freq;
end;
PlaySound;
Sleep(2000);
Application.ProcessMessages;
end;
Result := True;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
f: file;
b: array[0..3] of byte;
count: integer;
begin
with opendialog1 do
if execute then
begin
Form1.Image1.Canvas.Rectangle(0, 0, Form1.Image1.Width, Form1.Image1.Height);
Label1.Font.Color := clBlack;
OpenWav(FileName);
if ValidateWav = False then
begin
Label1.Caption := 'Invalid File Data!';
Label1.Font.Color := clRed;
Exit;
end;
CloseWav;
end;
end;
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
CompressionCodes.Destroy;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
Image1.Canvas.Rectangle(0, 0, Image1.Width, Image1.Height);
CompressionCodes := TDictionary<integer, string>.Create;
CompressionCodes.Add(0, 'Unknown');
CompressionCodes.Add(1, 'PCM/Uncompressed');
CompressionCodes.Add(2, 'Microsoft ADPCM');
CompressionCodes.Add(6, 'ITU G.711 a-law');
CompressionCodes.Add(7, 'ITU G.711 µ-law');
CompressionCodes.Add(17, 'IMA ADPCM');
CompressionCodes.Add(20, 'ITU G.723 ADPCM (Yamaha)');
CompressionCodes.Add(49, 'GSM 6.10');
CompressionCodes.Add(64, 'ITU G.721 ADPCM');
CompressionCodes.Add(80, 'MPEG');
CompressionCodes.Add(85, 'ISO/MPEG');
CompressionCodes.Add(65536, 'Experimental');
end;
end.
The Code needs a TLabel, a Tbutton and an OpenFileDialog on the form.
I have problem with the File Playback. currently I create arrays of samples with the length of SamplesPerSecond and play them one after another with the delay of 2000 (delays less than 2000ms will raise error).
What I want now is how can I Read samples and play them one after another smoothly and without delay. and Also I want to be able to visualize every few samples on a graph as the file is being played.

Answer 1

Funny you post this when you did, because I just yesterday wrote a working WAV player using Microsoft's waveOut... API.
You are not reading through the RIFF chunks effectively/correctly. I strongly suggest you use Microsoft's Multimedia functions (mmioOpen(), mmioDescend(), mmioAscend() and mmioRead()) instead of using AssignFile() and BlockRead(). WAV files are more complicated than you think, the code you have shown is not flexible enough to handle everything it may encounter. For instance, FMT is not always the first chunk in a WAV file, and there may be other chunks present before the DATA chunk, which you are not skipping.
When using waveOutOpen(), you should pass the original WAVEFORMATEX as read from the file, rather than creating a new WAVEFORMATEX that you populate with interpreted values. Using MMIO functions, you can declare a WAVEFORMATEX variable, mmioDescend() into the FMT chunk, mmioRead() the entire chunk directly into the variable, and then pass the variable as-is to waveOutOpen().
When using waveOutWrite(), you should use multiple audio buffers that you loop through (you can pre-prepare them with waveOutPrepareHeader() before you start reading the audio sample data, so you are only preparing them once). If you supply the wave device with only one buffer at a time, you are likely to get choppy audio playback (which it sounds like you are). It is best to use at least 3 buffers (my player uses 20, but I may knock that back later):
Fill 2 buffers with sample data and pass them to waveOutWrite() right away, and fill the 3rd buffer while they are playing.
When your waveOutOpen() callback says the 1st buffer is done playing, pass the 3rd buffer to waveOutWrite() and fill the 1st buffer with new data.
When the callback says the 2nd buffer is done playing, pass the 1st buffer to waveOutWrite() and fill the 2nd buffer with new data.
When the callback says the 3rd buffer is done playing, pass the 2nd buffer to waveOutWrite() and fill the 3rd buffer with new data.
And so on, continuing this round-robin logic until the end of the DATA chunk is reached.
The wave device should always have at least 2 active audio buffers playing at any given time to avoid gaps in the playback. Let the callback tell you when each buffer is done so you can provide the next buffer.
I based my player code on David Overton's tutorial, which has a LOT of information, and code examples:
Playing Audio in Windows using waveOut Interface
http://www.et.hs-wismar.de/~litschke/TMS/Audioprogrammierung.pdf
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=4422&lngWId=3
The only tweaks I made to the tutorial's code was to:
using MMIO functions for file I/O.
using the RTL's memory management functions instead of OS memory functions.
changed the size of the audio buffers. David uses 8KB buffers, which I found caused garbage playback after a few seconds as the wave device was not being fed audio samples fast enough for my WAV files (which are GSM encoded, not PCM, so they have smaller sample sizes). I changed the buffer size to the nAvgBytesPerSec value reported by the FMT chunk, and then the audio played cleanly all the way through.
error handling.
Try this (translated to Delphi from my real code written in C++):
{
The following is based on code written by David Overton:
Playing Audio in Windows using waveOut Interface
http://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=4422&lngWId=3
https://www.et.hs-wismar.de/~litschke/TMS/Audioprogrammierung.pdf
But with some custom tweaks.
}
uses
..., Winapi.Windows, Winapi.MMSystem;
const
BLOCK_COUNT = 20;
procedure waveOutProc(hWaveOut: HWAVEOUT; uMsg: UINT; dwInstance, dwParam1, dwParam2: DWORD_PTR): stdcall; forward;
function writeAudio(hWaveOut: HWAVEOUT; data: PByte; size: Integer): Boolean; forward;
var
waveCriticalSection: CRITICAL_SECTION;
waveBlocks: PWaveHdr;
waveFreeBlockCount: Integer;
waveCurrentBlock: Integer;
buffer: array[0..1023] of Byte;
mmckinfoParent: MMCKINFO;
mmckinfoSubchunk: MMCKINFO;
dwFmtSize: DWORD;
dwDataSize: DWORD;
dwSizeToRead: DWORD;
hmmio: HMMIO;
wfxBuffer: array of Byte;
wfx: PWaveFormatEx;
hWaveOut: HWAVEOUT;
blockBuffer: array of Byte;
pBlockData: PByte;
i: Integer;
readBytes: LONG;
begin
...
hmmio := mmioOpen(PChar(FileName), nil, MMIO_READ or MMIO_DENYWRITE);
if hmmio = 0 then
raise Exception.Create('Unable to open WAV file');
try
mmckinfoParent.fccType := mmioStringToFOURCC('WAVE', 0);
if mmioDescend(hmmio, #mmckinfoParent, nil, MMIO_FINDRIFF) <> MMSYSERR_NOERROR then
raise Exception.CreateFmt('%s is not a WAVE file', [FileName]);
mmckinfoSubchunk.ckid := mmioStringToFOURCC('fmt', 0);
if mmioDescend(hmmio, #mmckinfoSubchunk, #mmckinfoParent, MMIO_FINDCHUNK) <> MMSYSERR_NOERROR then
raise Exception.Create('File has no FMT chunk');
dwFmtSize := mmckinfoSubchunk.cksize;
if dwFmtSize = 0 then
raise Exception.Create('File FMT chunk is empty');
SetLength(wfxBuffer, dwFmtSize);
wfx := PWaveFormatEx(Pointer(wfxBuffer));
if mmioRead(hmmio, PAnsiChar(wfx), dwFmtSize) <> dwFmtSize then
raise Exception.Create('Failed to read FMT chunk');
if mmioAscend(hmmio, #mmckinfoSubchunk, 0) <> MMSYSERR_NOERROR then
raise Exception.Create('Failed to ascend into RIFF chunk');
mmckinfoSubchunk.ckid := mmioStringToFOURCC('data', 0);
if mmioDescend(hmmio, #mmckinfoSubchunk, #mmckinfoParent, MMIO_FINDCHUNK) <> MMSYSERR_NOERROR then
raise Exception.Create('File has no DATA chunk');
dwDataSize := mmckinfoSubchunk.cksize;
if dwDataSize <> 0 then
begin
hWaveOut := 0;
if waveOutOpen(#hWaveOut, WAVE_MAPPER, wfx, DWORD_PTR(#waveOutProc), 0, CALLBACK_FUNCTION) <> MMSYSERR_NOERROR then
raise Exception.Create('Unable to open wave mapper device');
try
SetLength(blockBuffer, (sizeof(WAVEHDR) + wfx.nAvgBytesPerSec) * BLOCK_COUNT);
pBlockData := PByte(blockBuffer);
waveBlocks := PWaveHdr(pBlockData);
Inc(pBlockData, sizeof(WAVEHDR) * BLOCK_COUNT);
for i := 0 to BLOCK_COUNT-1 do
begin
ZeroMemory(#waveBlocks[i], sizeof(WAVEHDR));
waveBlocks[i].dwBufferLength := wfx.nAvgBytesPerSec;
waveBlocks[i].lpData := pBlockData;
if waveOutPrepareHeader(hWaveOut, #waveBlocks[i], sizeof(WAVEHDR)) <> MMSYSERR_NOERROR then
raise Exception.Create('Failed to prepare a WAV audio header');
Inc(pBlockData, wfx.nAvgBytesPerSec);
end;
waveFreeBlockCount := BLOCK_COUNT;
waveCurrentBlock := 0;
InitializeCriticalSection(#waveCriticalSection);
try
repeat
dwSizeToRead := Min(dwDataSize, sizeof(buffer));
readBytes := mmioRead(hmmio, PAnsiChar(buffer), dwSizeToRead);
if readBytes <= 0 then Break;
if readBytes < sizeof(buffer) then
ZeroMemory(#buffer[readBytes], sizeof(buffer) - readBytes);
writeAudio(hWaveOut, buffer, sizeof(buffer));
Dec(dwDataSize, readBytes);
until dwDataSize = 0;
writeAudio(hWaveOut, nil, 0);
while waveFreeBlockCount < BLOCK_COUNT do
Sleep(10);
for i := 0 to BLOCK_COUNT-1 do
begin
if (waveBlocks[i].dwFlags and WHDR_PREPARED) <> 0 then
waveOutUnprepareHeader(hWaveOut, #waveBlocks[i], sizeof(WAVEHDR));
end;
finally
DeleteCriticalSection(#waveCriticalSection);
end;
finally
waveOutClose(hWaveOut);
end;
end;
finally
mmioClose(hmmio, 0);
end;
end;
procedure waveOutProc(hWaveOut: HWAVEOUT; uMsg: UINT; dwInstance, dwParam1, dwParam2: DWORD_PTR); stdcall;
begin
if uMsg = WOM_DONE then
begin
EnterCriticalSection(&waveCriticalSection);
Inc(waveFreeBlockCount);
LeaveCriticalSection(&waveCriticalSection);
end;
end;
procedure writeAudio(hWaveOut: HWAVEOUT; data: PByte; size: Integer);
var
current: PWaveHdr;
remaining: Integer;
begin
current := #waveBlocks[waveCurrentBlock];
if data = nil then
begin
if current.dwUser <> 0 then
begin
if current.dwUser < current.dwBufferLength then
begin
remaining := Integer(current.dwBufferLength - current.dwUser);
ZeroMemory(current.lpData + current.dwUser, remaining);
Inc(current.dwUser, remainint);
end;
EnterCriticalSection(&waveCriticalSection);
Dec(waveFreeBlockCount);
LeaveCriticalSection(&waveCriticalSection);
if waveOutWrite(hWaveOut, current, sizeof(WAVEHDR)) <> MMSYSERR_NOERROR then
raise Exception.Create('Failed to write a WAV audio header');
end;
end else
begin
while size > 0 do
begin
remaining := Integer(current.dwBufferLength - current.dwUser);
if size < remaining then
begin
Move(data^, (current.lpData + current.dwUser)^, size);
Inc(current.dwUser, size);
Break;
end;
Move(data^, (current.lpData + current.dwUser)^, remaining);
Inc(current.dwUser, remaining);
Inc(data, remaining);
Dec(size, remaining);
EnterCriticalSection(&waveCriticalSection);
Dec(waveFreeBlockCount);
LeaveCriticalSection(&waveCriticalSection);
if waveOutWrite(hWaveOut, current, sizeof(WAVEHDR)) <> MMSYSERR_NOERROR then
raise Exception.Create('Failed to write a WAV audio header');
while waveFreeBlockCount = 0 do
Sleep(10);
Inc(waveCurrentBlock);
waveCurrentBlock := waveCurrentBlock mod BLOCK_COUNT;
current := #waveBlocks[waveCurrentBlock];
current.dwUser := 0;
end;
end;
end;
Regarding visualization of the samples, you are best off using a 3rd party component for that (and you probably should be using a 3rd party WAV player anyway, instead of writing API code manually), such as Mitov Software's AudioLab components.

Answer 2

UINT is an unsigned 32 bit integer which is not used in Delphi. Change UINT to "cardinal", which is Delphi's 32 bit unsigned integer.
Ian