From 416611cfa127df360d6902794b36e426477061a0 Mon Sep 17 00:00:00 2001 From: Jean-Marc Valin Date: Fri, 29 Jul 2016 13:47:07 -0400 Subject: biasing quantization --- celt/bands.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/celt/bands.c b/celt/bands.c index fa2d2a65..87791b4a 100644 --- a/celt/bands.c +++ b/celt/bands.c @@ -742,11 +742,18 @@ static void compute_theta(struct band_ctx *ctx, struct split_ctx *sctx, if (encode) { if (!stereo || ctx->theta_round == 0) + { itheta = (itheta*(opus_int32)qn+8192)>>14; - else if (ctx->theta_round < 0) - itheta = (itheta*(opus_int32)qn)>>14; - else - itheta = (itheta*(opus_int32)qn+16383)>>14; + } else { + int down; + /* Bias quantization towards itheta=0 and itheta=16384. */ + int bias = itheta > 8192 ? 32767/qn : -32767/qn; + down = IMIN(qn-1, IMAX(0, (itheta*(opus_int32)qn + bias)>>14)); + if (ctx->theta_round < 0) + itheta = down; + else + itheta = down+1; + } } /* Entropy coding of the angle. We use a uniform pdf for the time split, a step for stereo, and a triangular one for the rest. */ -- cgit v1.2.1