From e227902cecfb629fd113e9fd7c69cea6b98dd790 Mon Sep 17 00:00:00 2001 From: Nadia Holmquist Pedersen Date: Sun, 3 Mar 2024 16:58:59 +0100 Subject: Util_Audio: use basic linear interpolation Should remove the artifacts caused by the previous nearest resampling. May be worth replacing with something better in the future, but this is an improvement for now. --- src/frontend/Util_Audio.cpp | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/src/frontend/Util_Audio.cpp b/src/frontend/Util_Audio.cpp index 02b3026..25e04db 100644 --- a/src/frontend/Util_Audio.cpp +++ b/src/frontend/Util_Audio.cpp @@ -63,21 +63,28 @@ int AudioOut_GetNumSamples(int outlen) void AudioOut_Resample(s16* inbuf, int inlen, s16* outbuf, int outlen, int volume) { - float res_incr = inlen / (float)outlen; - float res_timer = 0; - int res_pos = 0; + double factor = (double) inlen / (double) outlen; + double inpos = -(factor / 2); + double vol = (double) volume / 256.f; - for (int i = 0; i < outlen; i++) + for (int i = 0; i < outlen * 2; i += 2) { - outbuf[i*2 ] = (inbuf[res_pos*2 ] * volume) >> 8; - outbuf[i*2+1] = (inbuf[res_pos*2+1] * volume) >> 8; - - res_timer += res_incr; - while (res_timer >= 1.0) - { - res_timer -= 1.0; - res_pos++; - } + double intpart_d; + double frac = modf(inpos, &intpart_d); + int intpart = (int) intpart_d; + + double l1 = inbuf[ intpart * 2]; + double l2 = inbuf[(intpart * 2) + 2]; + double r1 = inbuf[(intpart * 2) + 1]; + double r2 = inbuf[(intpart * 2) + 3]; + + double ldiff = l2 - l1; + double rdiff = r2 - r1; + + outbuf[i] = (s16) round((l1 + ldiff * frac) * vol); + outbuf[i+1] = (s16) round((r1 + rdiff * frac) * vol); + + inpos += factor; } } -- cgit v1.2.3