sdl_umsaudio.c

MPEG-4编解码的实现(包括MPEG4视音频编解码)

/*
    AIX support for the SDL - Simple DirectMedia Layer
    Copyright (C) 2000  Carsten Griwodz

    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

    Carsten Griwodz
    [e-mail]

    based on linux/SDL_dspaudio.c by Sam Lantinga
*/

#ifdef SAVE_RCSID
static char rcsid =
 "@(#) $Id: SDL_umsaudio.c,v 1.4 2002/04/22 21:38:02 wmay Exp $";
#endif

/* Allow access to a raw mixing buffer */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include "SDL_audio.h"
#include "SDL_error.h"
#include "SDL_audio_c.h"
#include "SDL_audiodev_c.h"
#include "SDL_umsaudio.h"

/* The tag name used by UMS audio */
#define UMS_DRIVER_NAME         "ums"

#define DEBUG_AUDIO 1

/* Audio driver functions */
static int UMS_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void UMS_PlayAudio(_THIS);
static Uint8 *UMS_GetAudioBuf(_THIS);
static void UMS_CloseAudio(_THIS);

static UMSAudioDevice_ReturnCode UADOpen(_THIS,  string device, string mode, long flags);
static UMSAudioDevice_ReturnCode UADClose(_THIS);
static UMSAudioDevice_ReturnCode UADGetBitsPerSample(_THIS, long* bits);
static UMSAudioDevice_ReturnCode UADSetBitsPerSample(_THIS, long bits);
static UMSAudioDevice_ReturnCode UADSetSampleRate(_THIS, long rate, long* set_rate);
static UMSAudioDevice_ReturnCode UADSetByteOrder(_THIS, string byte_order);
static UMSAudioDevice_ReturnCode UADSetAudioFormatType(_THIS, string fmt);
static UMSAudioDevice_ReturnCode UADSetNumberFormat(_THIS, string fmt);
static UMSAudioDevice_ReturnCode UADInitialize(_THIS);
static UMSAudioDevice_ReturnCode UADStart(_THIS);
static UMSAudioDevice_ReturnCode UADStop(_THIS);
static UMSAudioDevice_ReturnCode UADSetTimeFormat(_THIS,  UMSAudioTypes_TimeFormat fmt );
static UMSAudioDevice_ReturnCode UADWriteBuffSize(_THIS,  long* buff_size );
static UMSAudioDevice_ReturnCode UADWriteBuffRemain(_THIS,  long* buff_size );
static UMSAudioDevice_ReturnCode UADWriteBuffUsed(_THIS,  long* buff_size );
static UMSAudioDevice_ReturnCode UADSetDMABufferSize(_THIS,  long bytes, long* bytes_ret );
static UMSAudioDevice_ReturnCode UADSetVolume(_THIS,  long volume );
static UMSAudioDevice_ReturnCode UADSetBalance(_THIS,  long balance );
static UMSAudioDevice_ReturnCode UADSetChannels(_THIS,  long channels );
static UMSAudioDevice_ReturnCode UADPlayRemainingData(_THIS,  boolean block );
static UMSAudioDevice_ReturnCode UADEnableOutput(_THIS,  string output, long* left_gain, long* right_gain);
static UMSAudioDevice_ReturnCode UADWrite(_THIS,  UMSAudioTypes_Buffer* buff, long samples, long* samples_written);

/* Audio driver bootstrap functions */
static int Audio_Available(void)
{
    return 1;
}

static void Audio_DeleteDevice(_THIS)
{
    if(this->hidden->playbuf._buffer) free(this->hidden->playbuf._buffer);
    if(this->hidden->fillbuf._buffer) free(this->hidden->fillbuf._buffer);
    _somFree( this->hidden->umsdev );
    free(this->hidden);
    free(this);
}

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

    /*
     * Allocate and initialize management storage and private management
     * storage for this SDL-using library.
     */
    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));
#ifdef DEBUG_AUDIO
    fprintf(stderr, "Creating UMS Audio device\n");
#endif

    /*
     * Calls for UMS env initialization and audio object construction.
     */
    this->hidden->ev     = somGetGlobalEnvironment();
    this->hidden->umsdev = UMSAudioDeviceNew();

    /*
     * Set the function pointers.
     */
    this->OpenAudio   = UMS_OpenAudio;
    this->WaitAudio   = NULL;           /* we do blocking output */
    this->PlayAudio   = UMS_PlayAudio;
    this->GetAudioBuf = UMS_GetAudioBuf;
    this->CloseAudio  = UMS_CloseAudio;
    this->free        = Audio_DeleteDevice;

#ifdef DEBUG_AUDIO
    fprintf(stderr, "done\n");
#endif
    return this;
}

AudioBootStrap UMS_bootstrap = {
	UMS_DRIVER_NAME, "AUX UMS audio",
	Audio_Available, Audio_CreateDevice
};

static Uint8 *UMS_GetAudioBuf(_THIS)
{
#ifdef DEBUG_AUDIO
    fprintf(stderr, "enter UMS_GetAudioBuf\n");
#endif
    return this->hidden->fillbuf._buffer;
/*
    long                      bufSize;
    UMSAudioDevice_ReturnCode rc;

    rc = UADSetTimeFormat(this, UMSAudioTypes_Bytes );
    rc = UADWriteBuffSize(this,  bufSize );
*/
}

static void UMS_CloseAudio(_THIS)
{
    UMSAudioDevice_ReturnCode rc;

#ifdef DEBUG_AUDIO
    fprintf(stderr, "enter UMS_CloseAudio\n");
#endif
    rc = UADPlayRemainingData(this, TRUE);
    rc = UADStop(this);
    rc = UADClose(this);
}

static void UMS_PlayAudio(_THIS)
{
    UMSAudioDevice_ReturnCode rc;
    long                      samplesToWrite;
    long                      samplesWritten;
    UMSAudioTypes_Buffer      swpbuf;

#ifdef DEBUG_AUDIO
    fprintf(stderr, "enter UMS_PlayAudio\n");
#endif
    samplesToWrite = this->hidden->playbuf._length/this->hidden->bytesPerSample;
    do
    {
        rc = UADWrite(this,  &this->hidden->playbuf,
		       samplesToWrite,
	               &samplesWritten );
	samplesToWrite -= samplesWritten;

	/* rc values: UMSAudioDevice_Success
	 *            UMSAudioDevice_Failure
	 *            UMSAudioDevice_Preempted
	 *            UMSAudioDevice_Interrupted
	 *            UMSAudioDevice_DeviceError
	 */
	if ( rc == UMSAudioDevice_DeviceError ) {
#ifdef DEBUG_AUDIO
	    fprintf(stderr, "Returning from PlayAudio with devices error\n");
#endif
	    return;
	}
    }
    while(samplesToWrite>0);

    SDL_LockAudio();
    memcpy( &swpbuf,                &this->hidden->playbuf, sizeof(UMSAudioTypes_Buffer) );
    memcpy( &this->hidden->playbuf, &this->hidden->fillbuf, sizeof(UMSAudioTypes_Buffer) );
    memcpy( &this->hidden->fillbuf, &swpbuf,                sizeof(UMSAudioTypes_Buffer) );
    SDL_UnlockAudio();

#ifdef DEBUG_AUDIO
    fprintf(stderr, "Wrote audio data and swapped buffer\n");
#endif
}

#if 0
// 	/* Set the DSP frequency */
// 	value = spec->freq;
// 	if ( ioctl(this->hidden->audio_fd, SOUND_PCM_WRITE_RATE, &value) < 0 ) {
// 		SDL_SetError("Couldn't set audio frequency");
// 		return(-1);
// 	}
// 	spec->freq = value;
#endif

static int UMS_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
    char*  audiodev = "/dev/paud0";
    long   lgain;
    long   rgain;
    long   outRate;
    long   outBufSize;
    long   bitsPerSample;
    long   samplesPerSec;
    long   success;
    Uint16 test_format;
    int    frag_spec;
    UMSAudioDevice_ReturnCode rc;

#ifdef DEBUG_AUDIO
    fprintf(stderr, "enter UMS_OpenAudio\n");
#endif
    rc = UADOpen(this, audiodev,"PLAY", UMSAudioDevice_BlockingIO);
    if ( rc != UMSAudioDevice_Success ) {
	SDL_SetError("Couldn't open %s: %s", audiodev, strerror(errno));
	return -1;
    }
 
    rc = UADSetAudioFormatType(this, "PCM"); 

    success = 0;
    test_format = SDL_FirstAudioFormat(spec->format);
    do
    {
#ifdef DEBUG_AUDIO
        fprintf(stderr, "Trying format 0x%4.4x\n", test_format);
#endif
        switch ( test_format )
        {
        case AUDIO_U8:
/* from the mac code: better ? */
/* sample_bits = spec->size / spec->samples / spec->channels * 8; */
	    success       = 1;
            bitsPerSample = 8;
            rc = UADSetSampleRate(this,  spec->freq << 16, &outRate );
            rc = UADSetByteOrder(this, "MSB");       /* irrelevant */
            rc = UADSetNumberFormat(this, "UNSIGNED");
            break;
        case AUDIO_S8:
	    success       = 1;
            bitsPerSample = 8;
            rc = UADSetSampleRate(this,  spec->freq << 16, &outRate );