Commit b5eeab779f1a78fa38ea7bd04e41a58c5713199f
2017-01-24T00:08:24
audio: allow stereo Sint16 resampling fast path in SDL_AudioStream. This currently favors libsamplerate over the fast path (quality over speed), but I'm not sure that's the correct approach, as there may be surprising changes in performance metrics depending on what packages are available on a user's system. That being said, currently, the only thing with access to SDL_AudioStream is an SDL audio device's thread, and it might be mostly idle otherwise, so maybe this is generally good.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136
diff --git a/src/audio/SDL_audiocvt.c b/src/audio/SDL_audiocvt.c
index 82367f7..28e7156 100644
--- a/src/audio/SDL_audiocvt.c
+++ b/src/audio/SDL_audiocvt.c
@@ -858,7 +858,7 @@ SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
return (cvt->needed);
}
-typedef int (*SDL_ResampleAudioStreamFunc)(SDL_AudioStream *stream, const float *inbuf, const int inbuflen, float *outbuf, const int outbuflen);
+typedef int (*SDL_ResampleAudioStreamFunc)(SDL_AudioStream *stream, const void *inbuf, const int inbuflen, void *outbuf, const int outbuflen);
typedef void (*SDL_ResetAudioStreamResamplerFunc)(SDL_AudioStream *stream);
typedef void (*SDL_CleanupAudioStreamResamplerFunc)(SDL_AudioStream *stream);
@@ -890,8 +890,10 @@ struct SDL_AudioStream
#ifdef HAVE_LIBSAMPLERATE_H
static int
-SDL_ResampleAudioStream_SRC(SDL_AudioStream *stream, const float *inbuf, const int inbuflen, float *outbuf, const int outbuflen)
+SDL_ResampleAudioStream_SRC(SDL_AudioStream *stream, const void *_inbuf, const int inbuflen, void *_outbuf, const int outbuflen)
{
+ const float *inbuf = (const float *) _inbuf;
+ float *outbuf = (float *) _outbuf;
const int framelen = sizeof(float) * stream->pre_resample_channels;
SRC_STATE *state = (SRC_STATE *)stream->resampler_state;
SRC_DATA data;
@@ -970,26 +972,48 @@ SetupLibSampleRateResampling(SDL_AudioStream *stream)
typedef struct
{
SDL_bool resampler_seeded;
- float resampler_state[8];
+ union
+ {
+ float f[8];
+ Sint16 si16[2];
+ } resampler_state;
} SDL_AudioStreamResamplerState;
static int
-SDL_ResampleAudioStream(SDL_AudioStream *stream, const float *inbuf, const int inbuflen, float *outbuf, const int outbuflen)
+SDL_ResampleAudioStream(SDL_AudioStream *stream, const void *_inbuf, const int inbuflen, void *_outbuf, const int outbuflen)
{
+ const float *inbuf = (const float *) _inbuf;
+ float *outbuf = (float *) _outbuf;
SDL_AudioStreamResamplerState *state = (SDL_AudioStreamResamplerState*)stream->resampler_state;
const int chans = (int)stream->pre_resample_channels;
- SDL_assert(chans <= SDL_arraysize(state->resampler_state));
+ SDL_assert(chans <= SDL_arraysize(state->resampler_state.f));
if (!state->resampler_seeded) {
- int i;
- for (i = 0; i < chans; i++) {
- state->resampler_state[i] = inbuf[i];
- }
+ SDL_memcpy(state->resampler_state.f, inbuf, chans * sizeof (float));
state->resampler_seeded = SDL_TRUE;
}
- return SDL_ResampleAudioSimple(chans, stream->rate_incr, state->resampler_state, inbuf, inbuflen, outbuf, outbuflen);
+ return SDL_ResampleAudioSimple(chans, stream->rate_incr, state->resampler_state.f, inbuf, inbuflen, outbuf, outbuflen);
+}
+
+static int
+SDL_ResampleAudioStream_si16_c2(SDL_AudioStream *stream, const void *_inbuf, const int inbuflen, void *_outbuf, const int outbuflen)
+{
+ const Sint16 *inbuf = (const Sint16 *) _inbuf;
+ Sint16 *outbuf = (Sint16 *) _outbuf;
+ SDL_AudioStreamResamplerState *state = (SDL_AudioStreamResamplerState*)stream->resampler_state;
+ const int chans = (int)stream->pre_resample_channels;
+
+ SDL_assert(chans <= SDL_arraysize(state->resampler_state.si16));
+
+ if (!state->resampler_seeded) {
+ state->resampler_state.si16[0] = inbuf[0];
+ state->resampler_state.si16[1] = inbuf[1];
+ state->resampler_seeded = SDL_TRUE;
+ }
+
+ return SDL_ResampleAudioSimple_si16_c2(stream->rate_incr, state->resampler_state.si16, inbuf, inbuflen, outbuf, outbuflen);
}
static void
@@ -1016,6 +1040,9 @@ SDL_NewAudioStream(const SDL_AudioFormat src_format,
const int packetlen = 4096; /* !!! FIXME: good enough for now. */
Uint8 pre_resample_channels;
SDL_AudioStream *retval;
+#ifndef HAVE_LIBSAMPLERATE_H
+ const SDL_bool SRC_available = SDL_FALSE;
+#endif
retval = (SDL_AudioStream *) SDL_calloc(1, sizeof (SDL_AudioStream));
if (!retval) {
@@ -1043,11 +1070,22 @@ SDL_NewAudioStream(const SDL_AudioFormat src_format,
/* Not resampling? It's an easy conversion (and maybe not even that!). */
if (src_rate == dst_rate) {
retval->cvt_before_resampling.needed = SDL_FALSE;
- retval->cvt_before_resampling.len_mult = 1;
if (SDL_BuildAudioCVT(&retval->cvt_after_resampling, src_format, src_channels, dst_rate, dst_format, dst_channels, dst_rate) < 0) {
SDL_FreeAudioStream(retval);
return NULL; /* SDL_BuildAudioCVT should have called SDL_SetError. */
}
+ /* fast path special case for stereo Sint16 data that just needs resampling. */
+ } else if ((!SRC_available) && (src_channels == 2) && (dst_channels == 2) && (src_format == AUDIO_S16SYS) && (dst_format == AUDIO_S16SYS)) {
+ SDL_assert(src_rate != dst_rate);
+ retval->resampler_state = SDL_calloc(1, sizeof(SDL_AudioStreamResamplerState));
+ if (!retval->resampler_state) {
+ SDL_FreeAudioStream(retval);
+ SDL_OutOfMemory();
+ return NULL;
+ }
+ retval->resampler_func = SDL_ResampleAudioStream_si16_c2;
+ retval->reset_resampler_func = SDL_ResetAudioStreamResampler;
+ retval->cleanup_resampler_func = SDL_CleanupAudioStreamResampler;
} else {
/* Don't resample at first. Just get us to Float32 format. */
/* !!! FIXME: convert to int32 on devices without hardware float. */
@@ -1136,16 +1174,16 @@ SDL_AudioStreamPut(SDL_AudioStream *stream, const void *buf, const Uint32 _bufle
if (stream->dst_rate != stream->src_rate) {
const int workbuflen = buflen * ((int) SDL_ceil(stream->rate_incr));
- float *workbuf = (float *) EnsureBufferSize(&stream->resample_buffer, &stream->resample_buffer_len, workbuflen);
+ void *workbuf = EnsureBufferSize(&stream->resample_buffer, &stream->resample_buffer_len, workbuflen);
if (workbuf == NULL) {
return -1; /* probably out of memory. */
}
- buflen = stream->resampler_func(stream, (float *) buf, buflen, workbuf, workbuflen);
+ buflen = stream->resampler_func(stream, buf, buflen, workbuf, workbuflen);
buf = workbuf;
}
if (stream->cvt_after_resampling.needed) {
- const int workbuflen = buflen * stream->cvt_before_resampling.len_mult; /* will be "* 1" if not needed */
+ const int workbuflen = buflen * stream->cvt_after_resampling.len_mult; /* will be "* 1" if not needed */
Uint8 *workbuf;
if (buf == stream->resample_buffer) {