From f7f71b5795d708763eb0c55fe5e2cb051b2b69f4 Mon Sep 17 00:00:00 2001 From: Rostislav Pehlivanov Date: Sun, 12 Apr 2015 05:50:34 +0100 Subject: [PATCH] aacenc: Add support for Perceptual Noise Substitution energy values This commit implements support for writing the noise energy values used in PNS. The difference between regular scalefactors and noise energy values is that the latter require a small preamble (NOISE_PRE + energy_value_diff) to be written as the first noise-containing band. Any following noise energy values use the previous one to base their "diff" on. Ordinary scalefactors remain unchanged other than that they ignore the noise values. This commit should not change anything by itself, the following commits will bring it in use. Signed-off-by: Michael Niedermayer --- libavcodec/aac.h | 3 +++ libavcodec/aacenc.c | 17 ++++++++++++++--- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/libavcodec/aac.h b/libavcodec/aac.h index b25b40c9c6b..2701386376b 100644 --- a/libavcodec/aac.h +++ b/libavcodec/aac.h @@ -141,6 +141,9 @@ typedef struct PredictorState { #define SCALE_MAX_DIFF 60 ///< maximum scalefactor difference allowed by standard #define SCALE_DIFF_ZERO 60 ///< codebook index corresponding to zero scalefactor indices difference +#define NOISE_PRE 256 ///< preamble for NOISE_BT, put in bitstream with the first noise band +#define NOISE_PRE_BITS 9 ///< length of preamble + /** * Long Term Prediction */ diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c index 7015a2789ca..5288afb4a26 100644 --- a/libavcodec/aacenc.c +++ b/libavcodec/aacenc.c @@ -388,15 +388,26 @@ static void encode_band_info(AACEncContext *s, SingleChannelElement *sce) static void encode_scale_factors(AVCodecContext *avctx, AACEncContext *s, SingleChannelElement *sce) { - int off = sce->sf_idx[0], diff; + int diff, off_sf = sce->sf_idx[0], off_pns = sce->sf_idx[0]; + int noise_flag = 1; int i, w; for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) { for (i = 0; i < sce->ics.max_sfb; i++) { if (!sce->zeroes[w*16 + i]) { - diff = sce->sf_idx[w*16 + i] - off + SCALE_DIFF_ZERO; + if (sce->band_type[w*16 + i] == NOISE_BT) { + diff = sce->sf_idx[w*16 + i] - off_pns; + off_pns = sce->sf_idx[w*16 + i]; + if (noise_flag-- > 0) { + put_bits(&s->pb, NOISE_PRE_BITS, diff + NOISE_PRE); + continue; + } + } else { + diff = sce->sf_idx[w*16 + i] - off_sf; + off_sf = sce->sf_idx[w*16 + i]; + } + diff += SCALE_DIFF_ZERO; av_assert0(diff >= 0 && diff <= 120); - off = sce->sf_idx[w*16 + i]; put_bits(&s->pb, ff_aac_scalefactor_bits[diff], ff_aac_scalefactor_code[diff]); } } -- 2.39.2