This updates the copyright header to all be the same, which is
pretty much an update of where to mail request for a copy of the GPL
and the years of the MPD project. This also puts all committers under
'The Music Player Project' umbrella. These entries should go
individually in the AUTHORS file, for consistancy.

Use GLib's GError library for reporting output device failures.

Note that some init() methods don't clean up properly after a failure,
but that's ok for now, because the MPD core will abort anyway.

Renamed functions and variables.

The MPD core guarantees that the audio_output object is always in a
consistent state: either open or closed.  When open, it will not call
the open() method again, and when closed, it will not call play().
Removed several checks and the NULL initialization.

The method is empty, and we can simply set the method pointer to NULL
instead.

audio_output_get_name() has been removed, which was the only function
left in output_api.h.  The output plugin doesn't need the audio_output
object at all, remove the parameter from the init() method.

Use config_get_block_string("name") instead of audio_output_get_name().

The meaning of the chunk depends on the audio format; don't suggest a
specific format by declaring the pointer as "char*", pass "void*"
instead.

The old API required an output plugin to not return until all data
passed to the play() method is consumed.  Some output plugins have to
loop to fulfill that requirement, and may block during that.  Simplify
these, by letting them consume only part of the buffer: make play()
return the length of the consumed data.

writeSize is a memory size and its type should thus be size_t.  This
allows us to remove two explicit casts.

On some platforms, g_free() must be used for memory allocated by
GLib.  This patch intends to correct a lot of occurrences, but is
probably not complete.

All config_get_block_*() functions should accept constant config_param
pointers.

Eliminate some more getBlockParam() invocations.

This replaces lots of getBlockParam() invocations.

Renamed functions, types, variables.

g_strsplit() is more portable than strtok_r().

Use GLib's G_GNUC_UNUSED instead of gcc.h's mpd_unused.

There have been bug reports on MPD regarding 24 bit output via
libao/esd.  The "ao" plugin does not attempt fall back to 16 bit
currently, and thus fails to play 24 bit audio (i.e. all mp3 files).
Make it always use 16 bit samples for now, until more bits are
well-tested.

When ao_open_live() failed, MPD would ignore the error code in
"errno".  Make it print a meaningful error message.

The function audioOutputAo_error() did not implement all possible
libao error codes.  Support the rest of them, and fall back to
strerror().

When an output plugin fails to play a chunk, close it.  This replaces
various manual close() calls in nearly all plugins.

Don't return 0/-1 on success/error, but true/false.  Instead of int,
use bool for storing flags.

Don't compile the sources of disabled output plugins at all.

Again, no CamelCase in the directory name.

The last bit of CamelCase in audio_format.h.  Additionally, rename a
bunch of local variables.

The old struct initializers are error prone and don't allow moving
elements around.  Since we are going to overhaul some of the APIs
soon, it's easier to have all implementations use C99 initializers.

We have eliminated direct accesses to the audio_output struct from
the all output plugins.  Make it opaque for them, and move its real
declaration to output_internal.h, similar to decoder_internal.h.

Pass the opaque structure to plugin.init() only, which will return the
plugin's data pointer on success, and NULL on failure.  This data
pointer will be passed to all other methods instead of the
audio_output struct.

Reduce direct accesses to the audio_output struct from the plugins:
this time, eliminate all accesses to audio_output.name.  The name is
required by some plugins for log messages.

Since the output plugin returns a value indicating success or error,
we can have the output core code assign the "open" flag.

Pass the globally configured audio_format as a const pointer to
plugin.init().  plugin.open() gets a writable pointer which contains
the audio_format requested by the plugin.  Its initial value is either
the configured audio_format or the input file's audio_format.

Since the plugin struct is never modified, we should store it in
constant locations.

Also rename AudioOutputPlugin to struct audio_output_plugin, and use
forward declarations to reduce include dependencies.

Just like decoder_api.h, output_api.h provides the audio output API
which is used by the plugins.

Also enable -Wunused-parameter - this forces us to add the gcc
"unused" attribute to a lot of parameters (mostly library callback
functions), but it's worth it during code refactorizations.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7307 09075e82-0dd4-0310-85a5-a0d7c8717e4f

The audio output plugins should get a constant pointer, because they
must not modify the buffer.  Since the size is a non-negative buffer
size in bytes, we should change its type to size_t.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7293 09075e82-0dd4-0310-85a5-a0d7c8717e4f

This will make refactoring features easier, especially now that
pthreads support and larger refactorings are on the horizon.

Hopefully, this will make porting to other platforms (even
non-UNIX-like ones for masochists) easier, too.

os_compat.h will house all the #includes for system headers
considered to be the "core" of MPD.  Headers for optional
features will be left to individual source files.

git-svn-id: https://svn.musicpd.org/mpd/trunk@7130 09075e82-0dd4-0310-85a5-a0d7c8717e4f

git-svn-id: https://svn.musicpd.org/mpd/trunk@6289 09075e82-0dd4-0310-85a5-a0d7c8717e4f

call to FATAL().

git-svn-id: https://svn.musicpd.org/mpd/trunk@6276 09075e82-0dd4-0310-85a5-a0d7c8717e4f