view src/audio/arts/SDL_artsaudio.c @ 956:4263beff9e38

Date: Mon, 30 Aug 2004 18:20:25 +0200 From: Joost Baas Subject: why call arts artsc? I, and a few other people at the mplayer-docs-mailinglist were wondering why you decided to call arts artsc. I understand usually users have nothing to do with libsdl, just developers, but because you can choose the audio-driver being used by mplayer, one of which is sdl, and you can also choose the sdl subdriver, it is necessary to have a well-known or logical name. artsc is not the logical choice, and it's very hard to look up the right name if you don't know what you're looking for.
author Sam Lantinga <slouken@libsdl.org>
date Fri, 17 Sep 2004 13:25:06 +0000
parents 03fb90fc135e
children c9b51268668f
line wrap: on
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/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2004 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id$";
#endif

/* Allow access to a raw mixing buffer */

#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <unistd.h>

#include "SDL_audio.h"
#include "SDL_error.h"
#include "SDL_audiomem.h"
#include "SDL_audio_c.h"
#include "SDL_timer.h"
#include "SDL_audiodev_c.h"
#include "SDL_artsaudio.h"

#ifdef ARTSC_DYNAMIC
#include "SDL_name.h"
#include "SDL_loadso.h"
#else
#define SDL_NAME(X)	X
#endif

/* The tag name used by artsc audio */
#define ARTSC_DRIVER_NAME         "arts"

/* Audio driver functions */
static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void ARTSC_WaitAudio(_THIS);
static void ARTSC_PlayAudio(_THIS);
static Uint8 *ARTSC_GetAudioBuf(_THIS);
static void ARTSC_CloseAudio(_THIS);

#ifdef ARTSC_DYNAMIC

static const char *arts_library = ARTSC_DYNAMIC;
static void *arts_handle = NULL;
static int arts_loaded = 0;

static int (*SDL_NAME(arts_init))(void);
static void (*SDL_NAME(arts_free))(void);
static arts_stream_t (*SDL_NAME(arts_play_stream))(int rate, int bits, int channels, const char *name);
static int (*SDL_NAME(arts_stream_set))(arts_stream_t s, arts_parameter_t param, int value);
static int (*SDL_NAME(arts_stream_get))(arts_stream_t s, arts_parameter_t param);
static int (*SDL_NAME(arts_write))(arts_stream_t s, const void *buffer, int count);
static void (*SDL_NAME(arts_close_stream))(arts_stream_t s);

static struct {
	const char *name;
	void **func;
} arts_functions[] = {
	{ "arts_init",		(void **)&SDL_NAME(arts_init)		},
	{ "arts_free",		(void **)&SDL_NAME(arts_free)		},
	{ "arts_play_stream",	(void **)&SDL_NAME(arts_play_stream)	},
	{ "arts_stream_set",	(void **)&SDL_NAME(arts_stream_set)	},
	{ "arts_stream_get",	(void **)&SDL_NAME(arts_stream_get)	},
	{ "arts_write",		(void **)&SDL_NAME(arts_write)		},
	{ "arts_close_stream",	(void **)&SDL_NAME(arts_close_stream)	},
};

static void UnloadARTSLibrary()
{
	if ( arts_loaded ) {
		SDL_UnloadObject(arts_handle);
		arts_handle = NULL;
		arts_loaded = 0;
	}
}

static int LoadARTSLibrary(void)
{
	int i, retval = -1;

	arts_handle = SDL_LoadObject(arts_library);
	if ( arts_handle ) {
		arts_loaded = 1;
		retval = 0;
		for ( i=0; i<SDL_TABLESIZE(arts_functions); ++i ) {
			*arts_functions[i].func = SDL_LoadFunction(arts_handle, arts_functions[i].name);
			if ( !*arts_functions[i].func ) {
				retval = -1;
				UnloadARTSLibrary();
				break;
			}
		}
	}
	return retval;
}

#else

static void UnloadARTSLibrary()
{
	return;
}

static int LoadARTSLibrary(void)
{
	return 0;
}

#endif /* ARTSC_DYNAMIC */

/* Audio driver bootstrap functions */

static int Audio_Available(void)
{
	int available = 0;

	if ( LoadARTSLibrary() < 0 ) {
		return available;
	}
	if ( SDL_NAME(arts_init)() == 0 ) {
#define ARTS_CRASH_HACK	/* Play a stream so aRts doesn't crash */
#ifdef ARTS_CRASH_HACK
		arts_stream_t stream2;
		stream2=SDL_NAME(arts_play_stream)(44100, 16, 2, "SDL");
		SDL_NAME(arts_write)(stream2, "", 0);
		SDL_NAME(arts_close_stream)(stream2);
#endif
		available = 1;
		SDL_NAME(arts_free)();
	}
	UnloadARTSLibrary();

	return available;
}

static void Audio_DeleteDevice(SDL_AudioDevice *device)
{
	free(device->hidden);
	free(device);
	UnloadARTSLibrary();
}

static SDL_AudioDevice *Audio_CreateDevice(int devindex)
{
	SDL_AudioDevice *this;

	/* Initialize all variables that we clean on shutdown */
	LoadARTSLibrary();
	this = (SDL_AudioDevice *)malloc(sizeof(SDL_AudioDevice));
	if ( this ) {
		memset(this, 0, (sizeof *this));
		this->hidden = (struct SDL_PrivateAudioData *)
				malloc((sizeof *this->hidden));
	}
	if ( (this == NULL) || (this->hidden == NULL) ) {
		SDL_OutOfMemory();
		if ( this ) {
			free(this);
		}
		return(0);
	}
	memset(this->hidden, 0, (sizeof *this->hidden));
	stream = 0;

	/* Set the function pointers */
	this->OpenAudio = ARTSC_OpenAudio;
	this->WaitAudio = ARTSC_WaitAudio;
	this->PlayAudio = ARTSC_PlayAudio;
	this->GetAudioBuf = ARTSC_GetAudioBuf;
	this->CloseAudio = ARTSC_CloseAudio;

	this->free = Audio_DeleteDevice;

	return this;
}

AudioBootStrap ARTSC_bootstrap = {
	ARTSC_DRIVER_NAME, "Analog Realtime Synthesizer",
	Audio_Available, Audio_CreateDevice
};

/* This function waits until it is possible to write a full sound buffer */
static void ARTSC_WaitAudio(_THIS)
{
	Sint32 ticks;

	/* Check to see if the thread-parent process is still alive */
	{ static int cnt = 0;
		/* Note that this only works with thread implementations 
		   that use a different process id for each thread.
		*/
		if (parent && (((++cnt)%10) == 0)) { /* Check every 10 loops */
			if ( kill(parent, 0) < 0 ) {
				this->enabled = 0;
			}
		}
	}

	/* Use timer for general audio synchronization */
	ticks = ((Sint32)(next_frame - SDL_GetTicks()))-FUDGE_TICKS;
	if ( ticks > 0 ) {
		SDL_Delay(ticks);
	}
}

static void ARTSC_PlayAudio(_THIS)
{
	int written;

	/* Write the audio data */
	written = SDL_NAME(arts_write)(stream, mixbuf, mixlen);
	
	/* If timer synchronization is enabled, set the next write frame */
	if ( frame_ticks ) {
		next_frame += frame_ticks;
	}

	/* If we couldn't write, assume fatal error for now */
	if ( written < 0 ) {
		this->enabled = 0;
	}
#ifdef DEBUG_AUDIO
	fprintf(stderr, "Wrote %d bytes of audio data\n", written);
#endif
}

static Uint8 *ARTSC_GetAudioBuf(_THIS)
{
	return(mixbuf);
}

static void ARTSC_CloseAudio(_THIS)
{
	if ( mixbuf != NULL ) {
		SDL_FreeAudioMem(mixbuf);
		mixbuf = NULL;
	}
	if ( stream ) {
		SDL_NAME(arts_close_stream)(stream);
		stream = 0;
	}
	SDL_NAME(arts_free)();
}

static int ARTSC_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
	int bits, frag_spec;
	Uint16 test_format, format;

	/* Reset the timer synchronization flag */
	frame_ticks = 0.0;

	mixbuf = NULL;

	/* Try for a closest match on audio format */
	format = 0;
	bits = 0;
	for ( test_format = SDL_FirstAudioFormat(spec->format);
						! format && test_format; ) {
#ifdef DEBUG_AUDIO
		fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
		switch ( test_format ) {
			case AUDIO_U8:
				bits = 8;
				format = 1;
				break;
			case AUDIO_S16LSB:
				bits = 16;
				format = 1;
				break;
			default:
				format = 0;
				break;
		}
		if ( ! format ) {
			test_format = SDL_NextAudioFormat();
		}
	}
	if ( format == 0 ) {
		SDL_SetError("Couldn't find any hardware audio formats");
		return(-1);
	}
	spec->format = test_format;

	if ( SDL_NAME(arts_init)() != 0 ) {
		SDL_SetError("Unable to initialize ARTS");
		return(-1);
	}
	stream = SDL_NAME(arts_play_stream)(spec->freq, bits, spec->channels, "SDL");

	/* Calculate the final parameters for this audio specification */
	SDL_CalculateAudioSpec(spec);

	/* Determine the power of two of the fragment size */
	for ( frag_spec = 0; (0x01<<frag_spec) < spec->size; ++frag_spec );
	if ( (0x01<<frag_spec) != spec->size ) {
		SDL_SetError("Fragment size must be a power of two");
		return(-1);
	}
	frag_spec |= 0x00020000;	/* two fragments, for low latency */

#ifdef ARTS_P_PACKET_SETTINGS
	SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_SETTINGS, frag_spec);
#else
	SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_SIZE, frag_spec&0xffff);
	SDL_NAME(arts_stream_set)(stream, ARTS_P_PACKET_COUNT, frag_spec>>16);
#endif
	spec->size = SDL_NAME(arts_stream_get)(stream, ARTS_P_PACKET_SIZE);

	/* Allocate mixing buffer */
	mixlen = spec->size;
	mixbuf = (Uint8 *)SDL_AllocAudioMem(mixlen);
	if ( mixbuf == NULL ) {
		return(-1);
	}
	memset(mixbuf, spec->silence, spec->size);

	/* Get the parent process id (we're the parent of the audio thread) */
	parent = getpid();

	/* We're ready to rock and roll. :-) */
	return(0);
}