[FFmpeg-devel] [PATCH v2 2/3] [GSoC] [AAC] aacenc: Adjust the initial offset for PNS values
Rostislav Pehlivanov
atomnuker at gmail.com
Tue Apr 14 01:33:51 CEST 2015
This commit adjusts the intial offset for PNS values, introduced with commit f7f71b5795d708763eb0c55fe5e2cb051b2b69f4 earlier. This commit shifts the value in such a way that no further offsets are required in the aaccoder.c file. Earlier version of the PNS patch had 2 offsets in both the aaccoder and aacenc.
---
libavcodec/aac.h | 1 +
libavcodec/aacenc.c | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/libavcodec/aac.h b/libavcodec/aac.h
index 2701386..23ec085 100644
--- a/libavcodec/aac.h
+++ b/libavcodec/aac.h
@@ -143,6 +143,7 @@ typedef struct PredictorState {
#define NOISE_PRE 256 ///< preamble for NOISE_BT, put in bitstream with the first noise band
#define NOISE_PRE_BITS 9 ///< length of preamble
+#define NOISE_OFFSET 90 ///< subtracted from global gain, used as offset for the preamble
/**
* Long Term Prediction
diff --git a/libavcodec/aacenc.c b/libavcodec/aacenc.c
index 3e92bc4..998a875 100644
--- a/libavcodec/aacenc.c
+++ b/libavcodec/aacenc.c
@@ -388,7 +388,7 @@ static void encode_band_info(AACEncContext *s, SingleChannelElement *sce)
static void encode_scale_factors(AVCodecContext *avctx, AACEncContext *s,
SingleChannelElement *sce)
{
- int diff, off_sf = sce->sf_idx[0], off_pns = sce->sf_idx[0];
+ int diff, off_sf = sce->sf_idx[0], off_pns = sce->sf_idx[0] - NOISE_OFFSET;
int noise_flag = 1;
int i, w;
--
2.1.4
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