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lib/Audio/MPC.pm  view on Meta::CPAN

This is called when the decoder wants to acquire more data to decode. I<reader> is
the object as returned by C<< Audio::MPC::Reader->new >> and I<size> denotes the
number of bytes that should be read from the stream. The function is expected to
return the data read from the underlying filehandle.

    sub my_read {
	my ($reader, $size) = @_;
	read $reader->fh, my ($buf), $size;
	return $buf;
    }

=item * seek (reader, offset)

I<offset> is the byte position to seek to. The function is expected to return true
if the seek operation was succesful:

    sub my_seek {
	my ($reader, $offset) = @_;
	return seek $reader->fh, $offset, SEEK_SET;
    }

=item * tell (reader)

The function is expected to return the filepointer's current position in the stream:

    sub my_tell {
	my $reader = shift;
	return tell $reader->fh;
    }

=item * get_size (reader)

The function is expected to return the size of the complete data-stream:

    sub my_get_size {
	my $reader = shift;
	return -s $reader->fh;
    }

=item * canseek (reader)

The function is expected to return a true value if the underlying filehandle
is seekable. However, experiments showed that non-seekable streams cannot be
decoded and are therefore not handled at all:
    
    sub canseek {
	my $reader = shift;
	return seek $reader->fh, 0, SEEK_CUR;	# test if seek succeeded
    }

=back

=head1 EXPORT

These symbols are exported by default:

    WAV_HEADER_SIZE
    MPC_LITTLE_ENDIAN
    MPC_BIG_ENDIAN

=head1 BUGS AND LIMITATIONS

I am not aware of any outright bugs yet. 

A limitation of libmpcdec seems to be that you cannot decode from STDIN as it
is not seekable. It should however be possible to craft your own
C<Audio::MPC::Reader> object which maintains an internal character buffer as
userdata that can be used to fake up a seekable filehandle.

=for readme continue

=begin readme

=head1 INSTALLATION

To install this module type the following:

   perl Makefile.PL
   make
   make test
   make install

=head1 DEPENDENCIES

Due to a subtle but unpleasant interaction between C++ method overloading and
the perl internals, you need at least perl5.8.0. 

You need a working C++ compiler and libmpcdec as available from L<http://www.musepack.net/>.
Furthermore:

    Test::More
    Test::LongString

=end readme

=begin changes

=head1 Revision history for Perl extension Audio::MPC

=over 4

=item * 0.04  Tue Mar  7 11:44:00 CEST 2006
 
    - updated to use libmpcdec who replaces libmusepack

=item * 0.03  Fri Sep 30 08:02:00 CEST 2005
 
    - there was a segfault when a file passed by filename
      could not be opened: fixed
    - errstr() method now includes $! when appropriate
    - fixed the SYNOPSIS section of the perldocs:
      the little script given in there now works

=item * 0.02  Mon May 16 13:13:58 CEST 2005

    - check.c had the wrong #include that would prevent
      installation on most systems

=item * 0.01  Wed May  4 08:30:27 2005

    - original version; created by h2xs 1.23 with options