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.

Allocate the mixer object when it is configured.

Merged mixer_configure() into mixer_new().  mixer_new() was quite
useless anyway.

Don't use statically allocated mixer objects.

Return the default value in the conf_get_block_*() functions when
param==NULL was passed.

This simplifies a lot of code, because all initialization can be done
in one code path, regardless whether configuration is present.

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

Document alsa_data members.

frame_size is a memory size and should be a size_t, not a signed integer.

Renamed types, functions, variables.

Two bugs here led to a large number of interrupts being generated on the
sound card when ALSA output is being used. Because we specify no default
period_time, the sound card gives us 3000 interrupts/sec rather than a more
sane 20 or 30. This completes the revert of dd7711 already started by
4ca24f.

The larger bug was in the change to config_get_block_unsigned() and using 0
as the default value for both 'buffer_time' and 'period_time'. This means
any pre-setting of these options in newAlsaData() gets wiped out. Add a new
default for period_time, and ensure default values for buffer_time and
period_time are used if none are provided by the user.
Signed-off-by: Dan McGee <dan@archlinux.org>
[mk: set defaults in newAlsaData() to fix auto-configuration; renamed
"_MS" back to "_US" because ALSA expects microseconds, not milliseconds]
Signed-off-by: Max Kellermann <max@duempel.org>

Eliminate some more getBlockParam() invocations.

This replaces lots of getBlockParam() invocations.

No "force" parameter, pass a default value instead.

Renamed functions, types, variables.

This patch tryes to introduce pluggable mixer (struct mixer_plugin) along with some basic infrastructure (mixer_* functions). Instance of mixer (struct mixer) is used in
alsa and oss output plugin

All what's left in pcm_utils.h is the pcm_range() utility function,
which is only used internally by pcm_volume and pcm_mix.

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

Commit dd7711d8 removed MPD's default ALSA buffer_time.  The result
was a buffer size which was way too small for playing streams on some
sound hardware, and caused skips and distorted sound.  Revert the
default to 500 ms.

When using autodetection, AlsaData.device wasn't properly initialized
with NULL.  This broke autodetection randomly.

Make the pointers "device" and "name" non-const, so we don't need the
xfree() hack.  The default value is expressed as NULL.

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.

These macros are not available in older libasound versions (1.0.13
fails, 1.0.16 is ok).  Ignore the configuration if the constants are
not defined.

Added mpd.conf options for disabling automatic resamling, sample
format and channel conversion.  This way, users may choose to override
ALSA's automatic resampling, and use libsamplerate instead.

If the sample format isn't supported by the device (i.e. 24 bit on
low-end sound chips), fall back to 16 bit output.  There is code in
pcm_utils.c which converts PCM data to 16 bit.

Move code which loads configuration to alsa_configure().  This removes
one indent level.

ALSA does a good job measuring its buffer_time and period_time.  Don't
override its defaults, unless the user demands it.

Revert e4f5d6bd "re-enable-nonblocking, but sleep if busy".
Non-blocking mode with manual sleeping doesn't help at all (by the
way, the patch should have used snd_pcm_wait() instead of
my_usleep()).  ALSA knows much more about the hardware quirks, so we
just let it do the job.

A frame contains one sample per channel, thus it is sample_size *
channels.  This patch includes some cleanup for various locations
where the sample size for 24 bit audio was still 3 bytes (instead of
4).

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

"bits" and "channels" cannot be negative.

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.

Seeing the "mpd_" prefix _everywhere_ is mind-numbing as the
mind needs to retrain itself to skip over the first 4 tokens of
a type to get to its meaning.  So avoid having extra characters
on my terminal to make it easier to follow code at 2:30 am in
the morning.

Please report any new issues you may come across on Free
toolchains.  I realize how difficult it can be to build/maintain
cross-compiling toolchains and I have no intention of forcing
people to upgrade their toolchains to build mpd.

Tested with gcc 2.95.4 and and gcc 4.3.1 on x86-32.

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.

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