diff --git a/src/audio/SDL_audiocvt.c b/src/audio/SDL_audiocvt.c index 7dbb6f5a6..7e5251c6a 100644 --- a/src/audio/SDL_audiocvt.c +++ b/src/audio/SDL_audiocvt.c @@ -245,27 +245,60 @@ SDL_ResampleAudioSimple(const int chans, const double rate_incr, const int finalpos = (total * chans) - chans; const int dest_samples = (int)(((double)total) * rate_incr); const double src_incr = 1.0 / rate_incr; - float *dst = outbuf; - float *target = (dst + (dest_samples * chans)); - double idx = 0.0; + float *dst; + double idx; int i; SDL_assert((dest_samples * framelen) <= outbuflen); SDL_assert((inbuflen % framelen) == 0); - while (dst < target) { - const int pos = ((int)idx) * chans; - const float *src = &inbuf[pos]; - SDL_assert(pos <= finalpos); - for (i = 0; i < chans; i++) { - const float val = *(src++); - *(dst++) = (val + last_sample[i]) * 0.5f; - last_sample[i] = val; + if (rate_incr > 1.0) { + float *target = (outbuf + chans); + const float *earlier_sample = &inbuf[finalpos]; + float final_sample[8]; + dst = outbuf + (dest_samples * chans); + idx = (double) total; + + /* save this off so we can correctly maintain state between runs. */ + SDL_memcpy(final_sample, &inbuf[finalpos], framelen); + + while (dst > target) { + const int pos = ((int) idx) * chans; + const float *src = &inbuf[pos]; + SDL_assert(pos >= 0.0); + for (i = chans - 1; i >= 0; i--) { + const float val = *(--src); + *(--dst) = (val + earlier_sample[i]) * 0.5f; + } + earlier_sample = src; + idx -= src_incr; + } + + /* do last sample, interpolated against previous run's state. */ + for (i = chans - 1; i >= 0; i--) { + const float val = inbuf[i]; + *(--dst) = (val + last_sample[i]) * 0.5f; + } + SDL_memcpy(last_sample, final_sample, framelen); + dst = (outbuf + (dest_samples * chans)) - 1; + } else { + float *target = (outbuf + (dest_samples * chans)); + dst = outbuf; + idx = 0.0; + while (dst < target) { + const int pos = ((int) idx) * chans; + const float *src = &inbuf[pos]; + SDL_assert(pos <= finalpos); + for (i = 0; i < chans; i++) { + const float val = *(src++); + *(dst++) = (val + last_sample[i]) * 0.5f; + last_sample[i] = val; + } + idx += src_incr; } - idx += src_incr; } - return (int) ((dst - outbuf) * (int)sizeof(float)); + return (int) ((dst - outbuf) * ((int) sizeof (float))); } @@ -420,8 +453,8 @@ SDL_ResampleCVT(SDL_AudioCVT *cvt, const int chans, const SDL_AudioFormat format { const float *src = (const float *) cvt->buf; const int srclen = cvt->len_cvt; - float *dst = (float *) (cvt->buf + srclen); - const int dstlen = (cvt->len * cvt->len_mult) - srclen; + float *dst = (float *) cvt->buf; + const int dstlen = (cvt->len * cvt->len_mult); float state[8]; SDL_assert(format == AUDIO_F32SYS); @@ -429,8 +462,6 @@ SDL_ResampleCVT(SDL_AudioCVT *cvt, const int chans, const SDL_AudioFormat format SDL_memcpy(state, src, chans*sizeof(*src)); cvt->len_cvt = SDL_ResampleAudioSimple(chans, cvt->rate_incr, state, src, srclen, dst, dstlen); - - SDL_memcpy(cvt->buf, dst, cvt->len_cvt); if (cvt->filters[++cvt->filter_index]) { cvt->filters[cvt->filter_index](cvt, format); } @@ -492,10 +523,6 @@ SDL_BuildAudioResampleCVT(SDL_AudioCVT * cvt, const int dst_channels, cvt->len_ratio /= ((double) src_rate) / ((double) dst_rate); } - /* the buffer is big enough to hold the destination now, but - we need it large enough to hold a separate scratch buffer. */ - cvt->len_mult *= 2; - return 1; /* added a converter. */ }