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Fixed audio data swizzling when the device channel map already matches what SDL expects

This commit is contained in:
Sam Lantinga 2016-10-28 16:47:06 -07:00
parent 39ba2ab835
commit fdcac1c24f
2 changed files with 37 additions and 7 deletions
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41
src/audio/alsa/SDL_alsa_audio.c
View File

@ -91,6 +91,8 @@ static int (*ALSA_snd_pcm_reset)(snd_pcm_t *);
static int (*ALSA_snd_device_name_hint) (int, const char *, void ***);
static char* (*ALSA_snd_device_name_get_hint) (const void *, const char *);
static int (*ALSA_snd_device_name_free_hint) (void **);
static snd_pcm_chmap_t* (*ALSA_snd_pcm_get_chmap) (snd_pcm_t *);
static int (*ALSA_snd_pcm_chmap_print) (const snd_pcm_chmap_t *map, size_t maxlen, char *buf);
#ifdef SDL_AUDIO_DRIVER_ALSA_DYNAMIC
#define snd_pcm_hw_params_sizeof ALSA_snd_pcm_hw_params_sizeof
@ -155,6 +157,8 @@ load_alsa_syms(void)
SDL_ALSA_SYM(snd_device_name_hint);
SDL_ALSA_SYM(snd_device_name_get_hint);
SDL_ALSA_SYM(snd_device_name_free_hint);
SDL_ALSA_SYM(snd_pcm_get_chmap);
SDL_ALSA_SYM(snd_pcm_chmap_print);
return 0;
}
@ -255,25 +259,25 @@ ALSA_WaitDevice(_THIS)
tmp = ptr[3]; ptr[3] = ptr[5]; ptr[5] = tmp; \
}
static SDL_INLINE void
static void
swizzle_alsa_channels_6_64bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint64, buffer, bufferlen);
}
static SDL_INLINE void
static void
swizzle_alsa_channels_6_32bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint32, buffer, bufferlen);
}
static SDL_INLINE void
static void
swizzle_alsa_channels_6_16bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint16, buffer, bufferlen);
}
static SDL_INLINE void
static void
swizzle_alsa_channels_6_8bit(void *buffer, Uint32 bufferlen)
{
SWIZ6(Uint8, buffer, bufferlen);
@ -286,7 +290,7 @@ swizzle_alsa_channels_6_8bit(void *buffer, Uint32 bufferlen)
* Called right before feeding this->hidden->mixbuf to the hardware. Swizzle
* channels from Windows/Mac order to the format alsalib will want.
*/
static SDL_INLINE void
static void
swizzle_alsa_channels(_THIS, void *buffer, Uint32 bufferlen)
{
if (this->spec.channels == 6) {
@ -302,6 +306,13 @@ swizzle_alsa_channels(_THIS, void *buffer, Uint32 bufferlen)
/* !!! FIXME: update this for 7.1 if needed, later. */
}
/* Some devices have the right channel map, no swizzling necessary */
static void
no_swizzle(_THIS, void *buffer, Uint32 bufferlen)
{
return;
}
static void
ALSA_PlayDevice(_THIS)
@ -311,7 +322,7 @@ ALSA_PlayDevice(_THIS)
this->spec.channels;
snd_pcm_uframes_t frames_left = ((snd_pcm_uframes_t) this->spec.samples);
swizzle_alsa_channels(this, this->hidden->mixbuf, frames_left);
this->hidden->swizzle_func(this, this->hidden->mixbuf, frames_left);
while ( frames_left > 0 && SDL_AtomicGet(&this->enabled) ) {
int status;
@ -398,7 +409,7 @@ ALSA_CaptureFromDevice(_THIS, void *buffer, int buflen)
frames_left -= status;
}
swizzle_alsa_channels(this, buffer, total_frames - frames_left);
this->hidden->swizzle_func(this, buffer, total_frames - frames_left);
return (total_frames - frames_left) * frame_size;
}
@ -548,6 +559,8 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
SDL_AudioFormat test_format = 0;
unsigned int rate = 0;
unsigned int channels = 0;
snd_pcm_chmap_t *chmap;
char chmap_str[64];
/* Initialize all variables that we clean on shutdown */
this->hidden = (struct SDL_PrivateAudioData *)
@ -640,6 +653,20 @@ ALSA_OpenDevice(_THIS, void *handle, const char *devname, int iscapture)
}
this->spec.format = test_format;
/* Validate number of channels and determine if swizzling is necessary
* Assume original swizzling, until proven otherwise.
*/
this->hidden->swizzle_func = swizzle_alsa_channels;
chmap = ALSA_snd_pcm_get_chmap(pcm_handle);
if (chmap) {
ALSA_snd_pcm_chmap_print(chmap, sizeof(chmap_str), chmap_str);
if (SDL_strcmp("FL FR FC LFE RL RR", chmap_str) == 0 ||
SDL_strcmp("FL FR FC LFE SL SR", chmap_str) == 0) {
this->hidden->swizzle_func = no_swizzle;
}
free(chmap);
}
/* Set the number of channels */
status = ALSA_snd_pcm_hw_params_set_channels(pcm_handle, hwparams,
this->spec.channels);

3
src/audio/alsa/SDL_alsa_audio.h
View File

@ -38,6 +38,9 @@ struct SDL_PrivateAudioData
/* Raw mixing buffer */
Uint8 *mixbuf;
int mixlen;
/* swizzle function */
void (*swizzle_func)(_THIS, void *buffer, Uint32 bufferlen);
};
#endif /* _SDL_ALSA_audio_h */