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authorJustin Ruggles <justin.ruggles@gmail.com>2011-06-27 14:29:33 -0400
committerJustin Ruggles <justin.ruggles@gmail.com>2011-07-01 13:02:11 -0400
commit523b7eba19590652b7ba19c5bdd85dd257bfe4f7 (patch)
treeb5d326ff4d73740275cae5bf623eabcbee692cb6
parent6054cd25b4d7dce97c4fa3cc6e4757ba1e59ab86 (diff)
downloadffmpeg-523b7eba19590652b7ba19c5bdd85dd257bfe4f7.tar.gz
ac3enc: clip coefficients after MDCT.
This ensures that any processing between the MDCT and exponent extraction will be using clipped coefficients.
-rw-r--r--libavcodec/ac3enc.h4
-rw-r--r--libavcodec/ac3enc_fixed.c9
-rw-r--r--libavcodec/ac3enc_float.c9
-rw-r--r--libavcodec/ac3enc_template.c16
4 files changed, 35 insertions, 3 deletions
diff --git a/libavcodec/ac3enc.h b/libavcodec/ac3enc.h
index be62656650..54f427a523 100644
--- a/libavcodec/ac3enc.h
+++ b/libavcodec/ac3enc.h
@@ -50,12 +50,16 @@
#if CONFIG_AC3ENC_FLOAT
#define AC3_NAME(x) ff_ac3_float_ ## x
#define MAC_COEF(d,a,b) ((d)+=(a)*(b))
+#define COEF_MIN (-16777215.0/16777216.0)
+#define COEF_MAX ( 16777215.0/16777216.0)
typedef float SampleType;
typedef float CoefType;
typedef float CoefSumType;
#else
#define AC3_NAME(x) ff_ac3_fixed_ ## x
#define MAC_COEF(d,a,b) MAC64(d,a,b)
+#define COEF_MIN -16777215
+#define COEF_MAX 16777215
typedef int16_t SampleType;
typedef int32_t CoefType;
typedef int64_t CoefSumType;
diff --git a/libavcodec/ac3enc_fixed.c b/libavcodec/ac3enc_fixed.c
index d55720eb80..ea3a46cdfa 100644
--- a/libavcodec/ac3enc_fixed.c
+++ b/libavcodec/ac3enc_fixed.c
@@ -104,6 +104,15 @@ static void scale_coefficients(AC3EncodeContext *s)
}
+/**
+ * Clip MDCT coefficients to allowable range.
+ */
+static void clip_coefficients(DSPContext *dsp, int32_t *coef, unsigned int len)
+{
+ dsp->vector_clip_int32(coef, coef, COEF_MIN, COEF_MAX, len);
+}
+
+
static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
{
AC3EncodeContext *s = avctx->priv_data;
diff --git a/libavcodec/ac3enc_float.c b/libavcodec/ac3enc_float.c
index 12d6b19241..718cc1f2b2 100644
--- a/libavcodec/ac3enc_float.c
+++ b/libavcodec/ac3enc_float.c
@@ -111,6 +111,15 @@ static void scale_coefficients(AC3EncodeContext *s)
}
+/**
+ * Clip MDCT coefficients to allowable range.
+ */
+static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len)
+{
+ dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len);
+}
+
+
#if CONFIG_AC3_ENCODER
AVCodec ff_ac3_encoder = {
"ac3",
diff --git a/libavcodec/ac3enc_template.c b/libavcodec/ac3enc_template.c
index 85eea54a4a..c7243c7644 100644
--- a/libavcodec/ac3enc_template.c
+++ b/libavcodec/ac3enc_template.c
@@ -41,6 +41,8 @@ static void apply_window(DSPContext *dsp, SampleType *output,
static int normalize_samples(AC3EncodeContext *s);
+static void clip_coefficients(DSPContext *dsp, CoefType *coef, unsigned int len);
+
int AC3_NAME(allocate_sample_buffers)(AC3EncodeContext *s)
{
@@ -171,8 +173,8 @@ static void apply_channel_coupling(AC3EncodeContext *s)
cpl_coef[i] += ch_coef[i];
}
- /* coefficients must be clipped to +/- 1.0 in order to be encoded */
- s->dsp.vector_clipf(cpl_coef, cpl_coef, -1.0f, 1.0f, num_cpl_coefs);
+ /* coefficients must be clipped in order to be encoded */
+ clip_coefficients(&s->dsp, cpl_coef, num_cpl_coefs);
/* scale coupling coefficients from float to 24-bit fixed-point */
s->ac3dsp.float_to_fixed24(&block->fixed_coef[CPL_CH][cpl_start],
@@ -300,6 +302,7 @@ static void apply_channel_coupling(AC3EncodeContext *s)
if (!block->cpl_in_use || !block->new_cpl_coords)
continue;
+ clip_coefficients(&s->dsp, cpl_coords[blk][1], s->fbw_channels * 16);
s->ac3dsp.float_to_fixed24(fixed_cpl_coords[blk][1],
cpl_coords[blk][1],
s->fbw_channels * 16);
@@ -433,7 +436,11 @@ int AC3_NAME(encode_frame)(AVCodecContext *avctx, unsigned char *frame,
apply_mdct(s);
- scale_coefficients(s);
+ if (s->fixed_point)
+ scale_coefficients(s);
+
+ clip_coefficients(&s->dsp, s->blocks[0].mdct_coef[1],
+ AC3_MAX_COEFS * AC3_MAX_BLOCKS * s->channels);
s->cpl_on = s->cpl_enabled;
ff_ac3_compute_coupling_strategy(s);
@@ -443,6 +450,9 @@ int AC3_NAME(encode_frame)(AVCodecContext *avctx, unsigned char *frame,
compute_rematrixing_strategy(s);
+ if (!s->fixed_point)
+ scale_coefficients(s);
+
ff_ac3_apply_rematrixing(s);
ff_ac3_process_exponents(s);