Re: [pygame] How to play a sound from a "file" of infinite size?

[Tomasz Primke <tprimke@xxxxxxxxxx>]

The file format?

Well, it's hard to say. It's a sap file, and I suspect, that the SAP library 
(the one, that can "render" samples, that can be played) simulates some 
POKEY chip (AFAIK - it was used in 8-bit Atari computers) to generate 
samples from a sap file. Quite interesting - isn't it?


Your idea looks quite interesting, although I wonder, what would it sound 
like (one melody split into many pieces...). Perhaps I'll try it. Perhaps 
it would be a good idea to make the length of the played Sound object an 
advanced parameter of the player.

The main problem, that I'm afraid of, is that I don't know the lenght of the 
song, that is being played. The only thing I can do is render the next 
sample of this song. Therefore all these samples must be played one after 
another - and I hope, that Python will be fast enough to play it smoothly.


Dnia wtorek 07 luty 2006 08:25, David Tweet napisał:
> Hi,
> I'm wondering, what is the file format of your audio?
>
> If you can read your raw sample data from your audio file into a
> 2-dimensional Numeric array, and you are careful about mixer
> initialization settings, you can use pygame.sndarray.make_sound to create
> the Sound object for you.  You can make it loop and segue (channel.queue)
> into other Sound objects with no gap in the buffer, but you don't have
> access directly to the samples in the buffer.  The main disadvantage is
> (afaik) Sound objects have to be loaded entirely into memory, so it's not
> so great for a long piece of music.  You could run a loop that would read
> like a 5-second piece of sample data and load it into a Sound object and
> then queue it and then wait, but it might not end up being very
> efficient, I don't know.
>
> On the other hand, pygame.mixer.music will stream from several different
> file formats without loading the whole thing into memory, and will
> support looping, but not in a completely seamless manner.
>
> On Mon, February 6, 2006 9:09 pm, Tomasz Primke said:
> > I'd like to write a player, that would be able to play files in some
> > rare format. I have a library (written in C), that can be used to play
> > such a files, but I'm not sure about the way that I should use PyGame
> > to code my player.
> >
> > On a GNU/Linux system, soundcard (a device) is a file /dev/dsp. When
> > someone
> > wants to play a wav file, all that must be done is write this wav file
> > to this device:
> >
> >   $ dd if=file.wav of=/dev/dsp
> >
> > when "if" means the input file, and "of" means the output file (the dd
> > command reads the input file and write its content to the output file).
> >
> > In the program written in C all the playing is done as follows:
> >
> >   char buffer[size]; // size = 20-40 kB
> >   while (1)
> >    {
> >     render_buffer( buffer, size );
> >     play_buffer( buffer );
> >    }
> >
> > On GNU/Linux all the play_buffer function does is write the buffer to
> > the /dev/dsp file (so the result is the same as with the dd command
> > shown before).
> >
> >
> > I could implement playing by wrapping all the code (written in C) in
> > Python,
> > but I'm afraid, that it would work on GNU/Linux only (because of this
> > writting to the /dev/dsp file). Although I want to write a player for
> > that system, I don't like the idea of giving up the portability of this
> > application so easily.
> >
> > In PyGame documentation I have found the function pygame.mixer.Sound,
> > that "loads a new sound object from a WAV file. File can be a filename
> > or a file-like object. (...)". So I thought, that this file-like object
> > idea sounds interesting. The problem is that I have never implemented
> > such an object yet and I'm not sure how to do it.
> >
> > As I suppose, a file-like object is an object, that implements all the
> > methods described in Python's documentation (point 2.3.9, "File
> > Objects"). I think I could implement such a class, but the problem is
> > that the buffer from the example shown above can be "rendered" forever
> > - so this file-object would be of infinite size. The question is: would
> > the pygame.mixer.Sound function load such a file-like object?