snd_sdl.c File Reference

#include <math.h>
#include <SDL.h>
#include "darkplaces.h"
#include "vid.h"
#include "snd_main.h"

Include dependency graph for snd_sdl.c:

Go to the source code of this file.

Functions
static void	Buffer_Callback (void *userdata, Uint8 *stream, int len)
unsigned int	SndSys_GetSoundTime (void)
	Returns the number of sample frames consumed since the sound started.
qbool	SndSys_Init (snd_format_t *fmt)
	Create "snd_renderbuffer", attempting to use the chosen sound format, but accepting if the driver wants to change it (e.g.
qbool	SndSys_LockRenderBuffer (void)
	Get the exclusive lock on "snd_renderbuffer".
void	SndSys_SendKeyEvents (void)
	if the sound system can generate events, send them
void	SndSys_Shutdown (void)
	Stop the sound card, delete "snd_renderbuffer" and free its other resources.
void	SndSys_Submit (void)
	Submit the contents of "snd_renderbuffer" to the sound card.
void	SndSys_UnlockRenderBuffer (void)
	Release the exclusive lock on "snd_renderbuffer".

Variables
static int	audio_device = 0
static unsigned int	sdlaudiotime = 0

Function Documentation

Buffer_Callback()

void Buffer_Callback ( void * userdata, Uint8 * stream, int len )

static

Definition at line 34 of file snd_sdl.c.

{
    unsigned int factor, RequestedFrames, MaxFrames, FrameCount;
    unsigned int StartOffset, EndOffset;
 
    factor = snd_renderbuffer->format.channels * snd_renderbuffer->format.width;
    if ((unsigned int)len % factor != 0)
        Sys_Error("SDL sound: invalid buffer length passed to Buffer_Callback (%d bytes)\n", len);
 
    RequestedFrames = (unsigned int)len / factor;
 
    if (snd_usethreadedmixing)
    {
        S_MixToBuffer(stream, RequestedFrames);
        if (snd_blocked)
            memset(stream, snd_renderbuffer->format.width == 1 ? 0x80 : 0, len);
        return;
    }
 
    // Transfert up to a chunk of samples from snd_renderbuffer to stream
    MaxFrames = snd_renderbuffer->endframe - snd_renderbuffer->startframe;
    if (MaxFrames > RequestedFrames)
        FrameCount = RequestedFrames;
    else
        FrameCount = MaxFrames;
    StartOffset = snd_renderbuffer->startframe % snd_renderbuffer->maxframes;
    EndOffset = (snd_renderbuffer->startframe + FrameCount) % snd_renderbuffer->maxframes;
    if (snd_blocked)
        memset(stream, snd_renderbuffer->format.width == 1 ? 0x80 : 0, len);
    else if (StartOffset > EndOffset)  // if the buffer wraps
    {
        unsigned int PartialLength1, PartialLength2;
 
        PartialLength1 = (snd_renderbuffer->maxframes - StartOffset) * factor;
        memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], PartialLength1);
 
        PartialLength2 = FrameCount * factor - PartialLength1;
        memcpy(&stream[PartialLength1], &snd_renderbuffer->ring[0], PartialLength2);
 
        // As of SDL 2.0 buffer needs to be fully initialized, so fill leftover part with silence
        // FIXME this is another place that assumes 8bit is always unsigned and others always signed
        memset(&stream[PartialLength1 + PartialLength2], snd_renderbuffer->format.width == 1 ? 0x80 : 0, len - (PartialLength1 + PartialLength2));
    }
    else
    {
        memcpy(stream, &snd_renderbuffer->ring[StartOffset * factor], FrameCount * factor);
 
        // As of SDL 2.0 buffer needs to be fully initialized, so fill leftover part with silence
        // FIXME this is another place that assumes 8bit is always unsigned and others always signed
        memset(&stream[FrameCount * factor], snd_renderbuffer->format.width == 1 ? 0x80 : 0, len - (FrameCount * factor));
    }
 
    snd_renderbuffer->startframe += FrameCount;
 
    if (FrameCount < RequestedFrames && developer_insane.integer && vid_activewindow)
        Con_DPrintf("SDL sound: %u sample frames missing\n", RequestedFrames - FrameCount);
 
    sdlaudiotime += RequestedFrames;
}

References Con_DPrintf(), developer_insane, int(), S_MixToBuffer(), sdlaudiotime, snd_blocked, snd_renderbuffer, snd_usethreadedmixing, Sys_Error(), and vid_activewindow.

Referenced by SndSys_Init().

SndSys_GetSoundTime()

unsigned int SndSys_GetSoundTime

(

void

)

Returns the number of sample frames consumed since the sound started.

Definition at line 209 of file snd_sdl.c.

{
    return sdlaudiotime;
}

References sdlaudiotime.

Referenced by S_PaintAndSubmit().

SndSys_Init()

qbool SndSys_Init

(

snd_format_t *

fmt

)

Create "snd_renderbuffer", attempting to use the chosen sound format, but accepting if the driver wants to change it (e.g.

7.1 to stereo or lowering the speed) Note: SDL automatically converts all formats, so this only fails if there is no audio

Definition at line 103 of file snd_sdl.c.

{
    unsigned int buffersize;
    SDL_AudioSpec wantspec;
    SDL_AudioSpec obtainspec;
 
    snd_threaded = false;
 
    Con_DPrint ("SndSys_Init: using the SDL module\n");
 
    // Init the SDL Audio subsystem
    if( SDL_InitSubSystem( SDL_INIT_AUDIO ) ) {
        Con_Print( "Initializing the SDL Audio subsystem failed!\n" );
        return false;
    }
 
    // SDL2 wiki recommends this range
    buffersize = bound(512, ceil((double)fmt->speed * snd_bufferlength.value / 1000.0), 8192);
 
    // Init the SDL Audio subsystem
    memset(&wantspec, 0, sizeof(wantspec));
    wantspec.callback = Buffer_Callback;
    wantspec.userdata = NULL;
    wantspec.freq = fmt->speed;
    wantspec.format = fmt->width == 1 ? AUDIO_U8 : (fmt->width == 2 ? AUDIO_S16SYS : AUDIO_F32);
    wantspec.channels = fmt->channels;
    wantspec.samples = CeilPowerOf2(buffersize);  // needs to be a power of 2 on some platforms.
 
    Con_Printf("Wanted audio Specification:\n"
                "    Channels  : %i\n"
                "    Format    : 0x%X\n"
                "    Frequency : %i\n"
                "    Samples   : %i\n",
                wantspec.channels, wantspec.format, wantspec.freq, wantspec.samples);
 
    if ((audio_device = SDL_OpenAudioDevice(NULL, 0, &wantspec, &obtainspec, SDL_AUDIO_ALLOW_FREQUENCY_CHANGE | SDL_AUDIO_ALLOW_CHANNELS_CHANGE)) == 0)
    {
        Con_Printf(CON_ERROR "Failed to open the audio device! (%s)\n", SDL_GetError() );
        return false;
    }
 
    Con_Printf("Obtained audio specification:\n"
                "    Channels  : %i\n"
                "    Format    : 0x%X\n"
                "    Frequency : %i\n"
                "    Samples   : %i\n",
                obtainspec.channels, obtainspec.format, obtainspec.freq, obtainspec.samples);
 
    fmt->speed = obtainspec.freq;
    fmt->channels = obtainspec.channels;
 
    snd_threaded = true;
 
    snd_renderbuffer = Snd_CreateRingBuffer(fmt, 0, NULL);
    if (snd_channellayout.integer == SND_CHANNELLAYOUT_AUTO)
        Cvar_SetValueQuick (&snd_channellayout, SND_CHANNELLAYOUT_STANDARD);
 
    sdlaudiotime = 0;
    SDL_PauseAudioDevice(audio_device, 0);
 
    return true;
}

References audio_device, bound, Buffer_Callback(), ceil(), CeilPowerOf2(), snd_format_t::channels, Con_DPrint(), CON_ERROR, Con_Print(), Con_Printf(), Cvar_SetValueQuick(), NULL, sdlaudiotime, snd_bufferlength, snd_channellayout, SND_CHANNELLAYOUT_AUTO, SND_CHANNELLAYOUT_STANDARD, Snd_CreateRingBuffer(), snd_renderbuffer, snd_threaded, snd_format_t::speed, and snd_format_t::width.

Referenced by S_Startup().

SndSys_LockRenderBuffer()

qbool SndSys_LockRenderBuffer

(

void

)

Get the exclusive lock on "snd_renderbuffer".

Definition at line 222 of file snd_sdl.c.

{
    SDL_LockAudioDevice(audio_device);
    return true;
}

References audio_device.

Referenced by S_PaintAndSubmit(), S_StopAllSounds(), and S_StopChannel().

SndSys_SendKeyEvents()

void SndSys_SendKeyEvents

(

void

)

if the sound system can generate events, send them

Definition at line 248 of file snd_sdl.c.

{
    // not supported
}

SndSys_Shutdown()

void SndSys_Shutdown

(

void

)

Stop the sound card, delete "snd_renderbuffer" and free its other resources.

Definition at line 174 of file snd_sdl.c.

{
    if (audio_device > 0) {
        SDL_CloseAudioDevice(audio_device);
        audio_device = 0;
    }
    if (snd_renderbuffer != NULL)
    {
        Mem_Free(snd_renderbuffer->ring);
        Mem_Free(snd_renderbuffer);
        snd_renderbuffer = NULL;
    }
}

References audio_device, Mem_Free, NULL, and snd_renderbuffer.

Referenced by S_Shutdown().

SndSys_Submit()

void SndSys_Submit

(

void

)

Submit the contents of "snd_renderbuffer" to the sound card.

Definition at line 196 of file snd_sdl.c.

{
    // Nothing to do here (this sound module is callback-based)
}

Referenced by S_PaintAndSubmit().

SndSys_UnlockRenderBuffer()

void SndSys_UnlockRenderBuffer

(

void

)

Release the exclusive lock on "snd_renderbuffer".

Definition at line 236 of file snd_sdl.c.

{
    SDL_UnlockAudioDevice(audio_device);
}

References audio_device.

Referenced by S_PaintAndSubmit(), S_StopAllSounds(), and S_StopChannel().

Variable Documentation

audio_device

int audio_device = 0

static

Definition at line 29 of file snd_sdl.c.

Referenced by SndSys_Init(), SndSys_LockRenderBuffer(), SndSys_Shutdown(), and SndSys_UnlockRenderBuffer().

sdlaudiotime

unsigned int sdlaudiotime = 0

static

Definition at line 28 of file snd_sdl.c.

Referenced by Buffer_Callback(), SndSys_GetSoundTime(), and SndSys_Init().