mpd/src/output/plugins/SndioOutputPlugin.cxx

/*
 * Copyright 2003-2017 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include "SndioOutputPlugin.hxx"
#include "../OutputAPI.hxx"
#include "util/Domain.hxx"
#include "Log.hxx"

/* work around a C++ incompatibility if the sndio API is emulated by
   libroar: libroar's "struct roar_service_stream" has a member named
   "new", which is an illegal identifier in C++ */
#define new new_

#include <sndio.h>

/* undo the libroar workaround */
#undef new

#include <stdexcept>

#ifndef SIO_DEVANY
/* this macro is missing in libroar-dev 1.0~beta2-3 (Debian Wheezy) */
#define SIO_DEVANY "default"
#endif

static constexpr unsigned MPD_SNDIO_BUFFER_TIME_MS = 250;

static constexpr Domain sndio_output_domain("sndio_output");

class SndioOutput final : AudioOutput {
	const char *const device;
	const unsigned buffer_time; /* in ms */
	struct sio_hdl *sio_hdl;

public:
	SndioOutput(const ConfigBlock &block);

	static AudioOutput *Create(EventLoop &,
				   const ConfigBlock &block) {
		return new SndioOutput(block);
	}

private:
	void Open(AudioFormat &audio_format) override;
	void Close() noexcept override;
	size_t Play(const void *chunk, size_t size) override;
};

SndioOutput::SndioOutput(const ConfigBlock &block)
	:AudioOutput(0),
	 device(block.GetBlockValue("device", SIO_DEVANY)),
	 buffer_time(block.GetBlockValue("buffer_time",
					 MPD_SNDIO_BUFFER_TIME_MS))
{
}

static bool
sndio_test_default_device()
{
	struct sio_hdl *sio_hdl;

	sio_hdl = sio_open(SIO_DEVANY, SIO_PLAY, 0);
	if (!sio_hdl) {
		FormatError(sndio_output_domain,
		            "Error opening default sndio device");
		return false;
	}

	sio_close(sio_hdl);
	return true;
}

void
SndioOutput::Open(AudioFormat &audio_format)
{
	struct sio_par par;
	unsigned bits, rate, chans;

	sio_hdl = sio_open(device, SIO_PLAY, 0);
	if (!sio_hdl)
		throw std::runtime_error("Failed to open default sndio device");

	switch (audio_format.format) {
	case SampleFormat::S16:
		bits = 16;
		break;
	case SampleFormat::S24_P32:
		bits = 24;
		break;
	case SampleFormat::S32:
		bits = 32;
		break;
	default:
		audio_format.format = SampleFormat::S16;
		bits = 16;
		break;
	}

	rate = audio_format.sample_rate;
	chans = audio_format.channels;

	sio_initpar(&par);
	par.bits = bits;
	par.rate = rate;
	par.pchan = chans;
	par.sig = 1;
	par.le = SIO_LE_NATIVE;
	par.appbufsz = rate * buffer_time / 1000;

	if (!sio_setpar(sio_hdl, &par) ||
	    !sio_getpar(sio_hdl, &par)) {
		sio_close(sio_hdl);
		throw std::runtime_error("Failed to set/get audio params");
	}

	if (par.bits != bits ||
	    par.rate < rate * 995 / 1000 ||
	    par.rate > rate * 1005 / 1000 ||
	    par.pchan != chans ||
	    par.sig != 1 ||
	    par.le != SIO_LE_NATIVE) {
		sio_close(sio_hdl);
		throw std::runtime_error("Requested audio params cannot be satisfied");
	}

	if (!sio_start(sio_hdl)) {
		sio_close(sio_hdl);
		throw std::runtime_error("Failed to start audio device");
	}
}

void
SndioOutput::Close()  noexcept
{
	sio_close(sio_hdl);
}

size_t
SndioOutput::Play(const void *chunk, size_t size)
{
	size_t n;

	n = sio_write(sio_hdl, chunk, size);
	if (n == 0 && sio_eof(sio_hdl) != 0)
		throw std::runtime_error("sndio write failed");
	return n;
}

const struct AudioOutputPlugin sndio_output_plugin = {
	"sndio",
	sndio_test_default_device,
	&SndioOutput::Create,
	nullptr,
};