pandory500/SDL-mirror
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Corrected dummy audio callback firing to be realistic, cleaned up tabs.

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--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401541
This commit is contained in:
Ryan C. Gordon 2006-03-14 19:12:49 +00:00
parent 48a79d3c30
commit 2b25e81b46
2 changed files with 24 additions and 11 deletions
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34
src/audio/dummy/SDL_dummyaudio.c
View file

@ -19,8 +19,7 @@
Sam Lantinga Sam Lantinga
slouken@libsdl.org slouken@libsdl.org
This file hacked^H^H^H^H^H^Hwritten by Ryan C. Gordon This file written by Ryan C. Gordon (icculus@icculus.org)
(icculus@icculus.org)
*/ */
#include "SDL_config.h" #include "SDL_config.h"
@ -37,10 +36,6 @@
/* The tag name used by DUMMY audio */ /* The tag name used by DUMMY audio */
#define DUMMYAUD_DRIVER_NAME "dummy" #define DUMMYAUD_DRIVER_NAME "dummy"
/* environment variables and defaults. */
#define DUMMYENVR_WRITEDELAY "SDL_DUMMYAUDIODELAY"
#define DUMMYDEFAULT_WRITEDELAY 150
/* Audio driver functions */ /* Audio driver functions */
static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec); static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec);
static void DUMMYAUD_WaitAudio(_THIS); static void DUMMYAUD_WaitAudio(_THIS);
@ -85,9 +80,6 @@ static SDL_AudioDevice *DUMMYAUD_CreateDevice(int devindex)
} }
SDL_memset(this->hidden, 0, (sizeof *this->hidden)); SDL_memset(this->hidden, 0, (sizeof *this->hidden));
envr = SDL_getenv(DUMMYENVR_WRITEDELAY);
this->hidden->write_delay = (envr) ? SDL_atoi(envr) : DUMMYDEFAULT_WRITEDELAY;
/* Set the function pointers */ /* Set the function pointers */
this->OpenAudio = DUMMYAUD_OpenAudio; this->OpenAudio = DUMMYAUD_OpenAudio;
this->WaitAudio = DUMMYAUD_WaitAudio; this->WaitAudio = DUMMYAUD_WaitAudio;
@ -108,12 +100,16 @@ AudioBootStrap DUMMYAUD_bootstrap = {
/* This function waits until it is possible to write a full sound buffer */ /* This function waits until it is possible to write a full sound buffer */
static void DUMMYAUD_WaitAudio(_THIS) static void DUMMYAUD_WaitAudio(_THIS)
{ {
SDL_Delay(this->hidden->write_delay); /* Don't block on first calls to simulate initial fragment filling. */
if (this->hidden->initial_calls)
this->hidden->initial_calls--;
else
SDL_Delay(this->hidden->write_delay);
} }
static void DUMMYAUD_PlayAudio(_THIS) static void DUMMYAUD_PlayAudio(_THIS)
{ {
/* no-op...this is a null driver. */ /* no-op...this is a null driver. */
} }
static Uint8 *DUMMYAUD_GetAudioBuf(_THIS) static Uint8 *DUMMYAUD_GetAudioBuf(_THIS)
@ -131,6 +127,8 @@ static void DUMMYAUD_CloseAudio(_THIS)
static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec) static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)
{ {
float bytes_per_sec = 0.0f;
/* Allocate mixing buffer */ /* Allocate mixing buffer */
this->hidden->mixlen = spec->size; this->hidden->mixlen = spec->size;
this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen); this->hidden->mixbuf = (Uint8 *) SDL_AllocAudioMem(this->hidden->mixlen);
@ -139,6 +137,20 @@ static int DUMMYAUD_OpenAudio(_THIS, SDL_AudioSpec *spec)
} }
SDL_memset(this->hidden->mixbuf, spec->silence, spec->size); SDL_memset(this->hidden->mixbuf, spec->silence, spec->size);
bytes_per_sec = (float) (((spec->format & 0xFF) / 8) *
spec->channels * spec->freq);
/*
* We try to make this request more audio at the correct rate for
* a given audio spec, so timing stays fairly faithful.
* Also, we have it not block at all for the first two calls, so
* it seems like we're filling two audio fragments right out of the
* gate, like other SDL drivers tend to do.
*/
this->hidden->initial_calls = 2;
this->hidden->write_delay =
(Uint32) ((((float) spec->size) / bytes_per_sec) * 1000.0f);
/* We're ready to rock and roll. :-) */ /* We're ready to rock and roll. :-) */
return(0); return(0);
} }

1
src/audio/dummy/SDL_dummyaudio.h
View file

@ -34,6 +34,7 @@ struct SDL_PrivateAudioData {
Uint8 *mixbuf; Uint8 *mixbuf;
Uint32 mixlen; Uint32 mixlen;
Uint32 write_delay; Uint32 write_delay;
Uint32 initial_calls;
}; };
#endif /* _SDL_dummyaudio_h */ #endif /* _SDL_dummyaudio_h */