// Load a SFX chunk into memory and ensure that it is locked.
static dboolean LockSound(sfxinfo_t *sfxinfo)
{
// If the sound isn't loaded, load it now
if (!GetAllocatedSoundBySfxInfoAndPitch(sfxinfo, NORM_PITCH))
if (!CacheSFX(sfxinfo))
return false;
LockAllocatedSound(GetAllocatedSoundBySfxInfoAndPitch(sfxinfo, NORM_PITCH));
return true;
}
//
// Starting a sound means adding it
// to the current list of active sounds
// in the internal channels.
// As the SFX info struct contains
// e.g. a pointer to the raw data,
// it is ignored.
// As our sound handling does not handle
// priority, it is ignored.
// Pitching (that is, increased speed of playback)
// is set, but currently not used by mixing.
//
int I_SDL_StartSound(sfxinfo_t *sfxinfo, int channel, int vol, int sep, int pitch)
{
allocated_sound_t *snd;
if (!sound_initialized || channel < 0 || channel >= NUM_CHANNELS)
return -1;
// Release a sound effect if there is already one playing
// on this channel
ReleaseSoundOnChannel(channel);
// Get the sound data
if (!LockSound(sfxinfo))
return -1;
snd = GetAllocatedSoundBySfxInfoAndPitch(sfxinfo, pitch);
if (!snd)
{
allocated_sound_t *newsnd;
// fetch the base sound effect, un-pitch-shifted
snd = GetAllocatedSoundBySfxInfoAndPitch(sfxinfo, NORM_PITCH);
if (!snd)
return -1;
if (s_randompitch)
{
newsnd = PitchShift(snd, pitch);
if (newsnd)
{
LockAllocatedSound(newsnd);
UnlockAllocatedSound(snd);
snd = newsnd;
}
}
}
else
LockAllocatedSound(snd);
// play sound
Mix_PlayChannel(channel, &snd->chunk, 0);
channels_playing[channel] = snd;
// set separation, etc.
I_SDL_UpdateSoundParams(channel, vol, sep);
return channel;
}
static boolean CacheSFX(sfxinfo_t *sfxinfo)
{
int lumpnum;
unsigned int lumplen;
int samplerate;
unsigned int length;
byte *data;
// need to load the sound
lumpnum = sfxinfo->lumpnum;
data = W_CacheLumpNum(lumpnum, PU_STATIC);
lumplen = W_LumpLength(lumpnum);
// Check the header, and ensure this is a valid sound
if (lumplen < 8
|| data[0] != 0x03 || data[1] != 0x00)
{
// Invalid sound
return false;
}
// 16 bit sample rate field, 32 bit length field
samplerate = (data[3] << 8) | data[2];
length = (data[7] << 24) | (data[6] << 16) | (data[5] << 8) | data[4];
// If the header specifies that the length of the sound is greater than
// the length of the lump itself, this is an invalid sound lump
// We also discard sound lumps that are less than 49 samples long,
// as this is how DMX behaves - although the actual cut-off length
// seems to vary slightly depending on the sample rate. This needs
// further investigation to better understand the correct
// behavior.
if (length > lumplen - 8 || length <= 48)
{
return false;
}
// The DMX sound library seems to skip the first 16 and last 16
// bytes of the lump - reason unknown.
data += 16;
length -= 32;
// Sample rate conversion
if (!ExpandSoundData(sfxinfo, data + 8, samplerate, length))
{
return false;
}
#ifdef DEBUG_DUMP_WAVS
{
char filename[16];
allocated_sound_t * snd;
M_snprintf(filename, sizeof(filename), "%s.wav",
DEH_String(sfxinfo->name));
snd = GetAllocatedSoundBySfxInfoAndPitch(sfxinfo, NORM_PITCH);
WriteWAV(filename, snd->chunk.abuf, snd->chunk.alen,mixer_freq);
}
#endif
// don't need the original lump any more
W_ReleaseLumpNum(lumpnum);
return true;
}
