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Programming => Packages and Libraries => Topic started by: Tomxe on April 26, 2025, 01:23:10 pm

Title: TAudio- play, edit, convert audio files
Post by: Tomxe on April 26, 2025, 01:23:10 pm
1) No DLLs required, no external programs
2) Can play, edit and convert audio files
3) Output format is currently only WAV
4) License: MIT

https://github.com/Xelitan/TAudio---audio-library-in-pure-Pascal/

Usage example:

Code: Pascal  [Select][+][-]
  1.   if not OpenDialog1.Execute then Exit;
  2.  
  3.   a := TAudio.Create;
  4.   a.LoadFromFile(OpenDialog1.Filename);
  5.   a.SaveToFile('output.wav');
  6.   a.Free;
Title: Re: TAudio- play, edit, convert audio files
Post by: wp on April 26, 2025, 02:39:27 pm
It's interesting to see an audio lib written in pure Pascal. But, since the audio is played by MMSystem's sndSoundPlay, it is windows-only -- if you put the "Play" and "Stop" methods as well as the MMSystem unit into a define {$IFDEF MSWINDOWS} it will be cross-platform, though.

Find in the attachment a small demo reading a wav and an mp3 file and displaying the samples in a chart. There seems to be an issue with the FFrame values which are not correctly signed (they should be declared as SmallInt rather than LongInt).

Title: Re: TAudio- play, edit, convert audio files
Post by: Tomxe on April 26, 2025, 03:54:49 pm
How can audio be played on Linux using only Lazarus built-in functions?
Title: Re: TAudio- play, edit, convert audio files
Post by: TRon on April 26, 2025, 04:53:51 pm
Quote from: Tomxe on April 26, 2025, 03:54:49 pm
How can audio be played on Linux using only Lazarus built-in functions?
You don't. Same for every other platform unless the hardware contains the audio-device out of the box.
Title: Re: TAudio- play, edit, convert audio files
Post by: Tomxe on April 27, 2025, 09:56:57 am
Quote from: wp on April 26, 2025, 02:39:27 pm
There seems to be an issue with the FFrame values which are not correctly signed (they should be declared as SmallInt rather than LongInt).

Instead of your Alarm01.wav I tested on your mp3 file converted to wav (attached). And looks fine on the graph.
Title: Re: TAudio- play, edit, convert audio files
Post by: wp on April 27, 2025, 02:36:44 pm
Because the demo that I had posted worked around the issue. Modify the i loop in Button1Click as follows to remove the workaround:

Code: Pascal  [Select][+][-]
  1.     for i := 0 to High(audio.FFrames) do
  2.       with audio do
  3.       begin
  4.         t := i / FSampleRate;
  5. //        yL := DecodeFrame(FFrames[i].Left);
  6. //        yR := DecodeFrame(FFrames[i].Right);
  7.         yL := FFrames[i].Left;
  8.         yR := FFrames[i].Right;
  9.         LeftChannelSeries.AddXY(t, yL);
  10.         RightChannelSeries.AddXY(t, yR);
  11.       end;
With this modification the plot of the Alarm01.wav looks as shown in the attached screenshot (and similarly for your converted sample-3s.wav). And when you zoom in you see that the negative part of the wave is shifted up to 65535. Basically this is because the file has a sample size of 16bits, and you read each sample by calling the GetU2 method of the reader. You assign the obtained word variable to the longint of the FFrames left/right channel - and this destroys the sign of the values: a $FFFF (-1) in the file becomes $0000FFFF in the FFrames (65535).

You can fix this by reading 16-bit sample files by calling the GetI2 method which reads the file values into 16-bit signed smallints and thus keeps the sign.
Code: Pascal  [Select][+][-]
  1. function TAudioWav.LoadFromStream(Str: TStream): Boolean;
  2. ...
  3.   else if FHandle.FSampleSize = 16 then begin
  4.     for i:=0 to NumFrames-1 do begin
  5.       FHandle.FFrames[i].Left := r.GetI2; //r.getU2;
  6.       if NumChannels>1 then
  7.         FHandle.FFrames[i].Right := r.GetI2; //r.getU2;
  8.     end;
  9.   end
  10. ...

Probably the same change needs to be made for the other GetU* calls in TAudioWav.LoadfromStream and probably also in the other file format readers. But I did not check this.
Title: Re: TAudio- play, edit, convert audio files
Post by: minesadorada on April 27, 2025, 03:33:45 pm
Sometimes a clever solution is too clever.

My component PlaySound under Linux simply polls all the various native sound players until it finds one that works.
This is old-style programming :)
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