[FFmpeg-cvslog] atrac3: Generalize gain compensation code
Maxim Poliakovski
git at videolan.org
Thu Oct 3 21:53:54 CEST 2013
ffmpeg | branch: master | Maxim Poliakovski <max_pole at gmx.de> | Mon Sep 30 23:14:51 2013 +0200| [79cbac8cd456c3f1c914bd1e7262b55e48de13a7] | committer: Diego Biurrun
atrac3: Generalize gain compensation code
Move it to the ATRAC common code, to reuse in the upcoming ATRAC3+ decoder.
Signed-off-by: Diego Biurrun <diego at biurrun.de>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=79cbac8cd456c3f1c914bd1e7262b55e48de13a7
---
libavcodec/atrac.c | 61 ++++++++++++++++++++++++++++++++++++
libavcodec/atrac.h | 45 ++++++++++++++++++++++++++
libavcodec/atrac3.c | 87 +++++++--------------------------------------------
3 files changed, 118 insertions(+), 75 deletions(-)
diff --git a/libavcodec/atrac.c b/libavcodec/atrac.c
index b34bff3..0f57215 100644
--- a/libavcodec/atrac.c
+++ b/libavcodec/atrac.c
@@ -63,6 +63,67 @@ void ff_atrac_generate_tables(void)
}
}
+av_cold void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
+ int loc_scale)
+{
+ int i;
+
+ gctx->loc_scale = loc_scale;
+ gctx->loc_size = 1 << loc_scale;
+ gctx->id2exp_offset = id2exp_offset;
+
+ /* Generate gain level table. */
+ for (i = 0; i < 16; i++)
+ gctx->gain_tab1[i] = powf(2.0, id2exp_offset - i);
+
+ /* Generate gain interpolation table. */
+ for (i = -15; i < 16; i++)
+ gctx->gain_tab2[i + 15] = powf(2.0, -1.0f / gctx->loc_size * i);
+}
+
+void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
+ AtracGainInfo *gc_now, AtracGainInfo *gc_next,
+ int num_samples, float *out)
+{
+ float lev, gc_scale, gain_inc;
+ int i, pos, lastpos;
+
+ gc_scale = gc_next->num_points ? gctx->gain_tab1[gc_next->lev_code[0]]
+ : 1.0f;
+
+ if (!gc_now->num_points) {
+ for (pos = 0; pos < num_samples; pos++)
+ out[pos] = in[pos] * gc_scale + prev[pos];
+ } else {
+ pos = 0;
+
+ for (i = 0; i < gc_now->num_points; i++) {
+ lastpos = gc_now->loc_code[i] << gctx->loc_scale;
+
+ lev = gctx->gain_tab1[gc_now->lev_code[i]];
+ gain_inc = gctx->gain_tab2[(i + 1 < gc_now->num_points ? gc_now->lev_code[i + 1]
+ : gctx->id2exp_offset) -
+ gc_now->lev_code[i] + 15];
+
+ /* apply constant gain level and overlap */
+ for (; pos < lastpos; pos++)
+ out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
+
+ /* interpolate between two different gain levels */
+ for (; pos < lastpos + gctx->loc_size; pos++) {
+ out[pos] = (in[pos] * gc_scale + prev[pos]) * lev;
+ lev *= gain_inc;
+ }
+ }
+
+ for (; pos < num_samples; pos++)
+ out[pos] = in[pos] * gc_scale + prev[pos];
+ }
+
+ /* copy the overlapping part into the delay buffer */
+ memcpy(prev, &in[num_samples], num_samples * sizeof(float));
+}
+
void ff_atrac_iqmf (float *inlo, float *inhi, unsigned int nIn, float *pOut, float *delayBuf, float *temp)
{
int i, j;
diff --git a/libavcodec/atrac.h b/libavcodec/atrac.h
index 4923caa..8909323 100644
--- a/libavcodec/atrac.h
+++ b/libavcodec/atrac.h
@@ -29,6 +29,26 @@
#ifndef AVCODEC_ATRAC_H
#define AVCODEC_ATRAC_H
+/**
+ * Gain control parameters for one subband.
+ */
+typedef struct AtracGainInfo {
+ int num_points; ///< number of gain control points
+ int lev_code[7]; ///< level at corresponding control point
+ int loc_code[7]; ///< location of gain control points
+} AtracGainInfo;
+
+/**
+ * Gain compensation context structure.
+ */
+typedef struct AtracGCContext {
+ float gain_tab1[16]; ///< gain compensation level table
+ float gain_tab2[31]; ///< gain compensation interpolation table
+ int id2exp_offset; ///< offset for converting level index into level exponent
+ int loc_scale; ///< scale of location code = 2^loc_scale samples
+ int loc_size; ///< size of location code in samples
+} AtracGCContext;
+
extern float ff_atrac_sf_table[64];
/**
@@ -37,6 +57,31 @@ extern float ff_atrac_sf_table[64];
void ff_atrac_generate_tables(void);
/**
+ * Initialize gain compensation context.
+ *
+ * @param gctx pointer to gain compensation context to initialize
+ * @param id2exp_offset offset for converting level index into level exponent
+ * @param loc_scale location size factor
+ */
+void ff_atrac_init_gain_compensation(AtracGCContext *gctx, int id2exp_offset,
+ int loc_scale);
+
+/**
+ * Apply gain compensation and perform the MDCT overlapping part.
+ *
+ * @param gctx pointer to gain compensation context
+ * @param in input buffer
+ * @param prev previous buffer to perform overlap against
+ * @param gc_now gain control information for current frame
+ * @param gc_next gain control information for next frame
+ * @param num_samples number of samples to process
+ * @param out output data goes here
+ */
+void ff_atrac_gain_compensation(AtracGCContext *gctx, float *in, float *prev,
+ AtracGainInfo *gc_now, AtracGainInfo *gc_next,
+ int num_samples, float *out);
+
+/**
* Quadrature mirror synthesis filter.
*
* @param inlo lower part of spectrum
diff --git a/libavcodec/atrac3.c b/libavcodec/atrac3.c
index 46aee65..5378d95 100644
--- a/libavcodec/atrac3.c
+++ b/libavcodec/atrac3.c
@@ -54,14 +54,8 @@
#define SAMPLES_PER_FRAME 1024
#define MDCT_SIZE 512
-typedef struct GainInfo {
- int num_gain_data;
- int lev_code[8];
- int loc_code[8];
-} GainInfo;
-
typedef struct GainBlock {
- GainInfo g_block[4];
+ AtracGainInfo g_block[4];
} GainBlock;
typedef struct TonalComponent {
@@ -111,6 +105,7 @@ typedef struct ATRAC3Context {
int scrambled_stream;
//@}
+ AtracGCContext gainc_ctx;
FFTContext mdct_ctx;
FmtConvertContext fmt_conv;
AVFloatDSPContext fdsp;
@@ -417,18 +412,17 @@ static int decode_tonal_components(GetBitContext *gb,
static int decode_gain_control(GetBitContext *gb, GainBlock *block,
int num_bands)
{
- int i, j, num_data;
+ int i, j;
int *level, *loc;
- GainInfo *gain = block->g_block;
+ AtracGainInfo *gain = block->g_block;
for (i = 0; i <= num_bands; i++) {
- num_data = get_bits(gb, 3);
- gain[i].num_gain_data = num_data;
+ gain[i].num_points = get_bits(gb, 3);
level = gain[i].lev_code;
loc = gain[i].loc_code;
- for (j = 0; j < gain[i].num_gain_data; j++) {
+ for (j = 0; j < gain[i].num_points; j++) {
level[j] = get_bits(gb, 4);
loc[j] = get_bits(gb, 5);
if (j && loc[j] <= loc[j - 1])
@@ -438,69 +432,12 @@ static int decode_gain_control(GetBitContext *gb, GainBlock *block,
/* Clear the unused blocks. */
for (; i < 4 ; i++)
- gain[i].num_gain_data = 0;
+ gain[i].num_points = 0;
return 0;
}
/**
- * Apply gain parameters and perform the MDCT overlapping part
- *
- * @param input input buffer
- * @param prev previous buffer to perform overlap against
- * @param output output buffer
- * @param gain1 current band gain info
- * @param gain2 next band gain info
- */
-static void gain_compensate_and_overlap(float *input, float *prev,
- float *output, GainInfo *gain1,
- GainInfo *gain2)
-{
- float g1, g2, gain_inc;
- int i, j, num_data, start_loc, end_loc;
-
-
- if (gain2->num_gain_data == 0)
- g1 = 1.0;
- else
- g1 = gain_tab1[gain2->lev_code[0]];
-
- if (gain1->num_gain_data == 0) {
- for (i = 0; i < 256; i++)
- output[i] = input[i] * g1 + prev[i];
- } else {
- num_data = gain1->num_gain_data;
- gain1->loc_code[num_data] = 32;
- gain1->lev_code[num_data] = 4;
-
- for (i = 0, j = 0; i < num_data; i++) {
- start_loc = gain1->loc_code[i] * 8;
- end_loc = start_loc + 8;
-
- g2 = gain_tab1[gain1->lev_code[i]];
- gain_inc = gain_tab2[gain1->lev_code[i + 1] -
- gain1->lev_code[i ] + 15];
-
- /* interpolate */
- for (; j < start_loc; j++)
- output[j] = (input[j] * g1 + prev[j]) * g2;
-
- /* interpolation is done over eight samples */
- for (; j < end_loc; j++) {
- output[j] = (input[j] * g1 + prev[j]) * g2;
- g2 *= gain_inc;
- }
- }
-
- for (; j < 256; j++)
- output[j] = input[j] * g1 + prev[j];
- }
-
- /* Delay for the overlapping part. */
- memcpy(prev, &input[256], 256 * sizeof(*prev));
-}
-
-/**
* Combine the tonal band spectrum and regular band spectrum
*
* @param spectrum output spectrum buffer
@@ -690,11 +627,10 @@ static int decode_channel_sound_unit(ATRAC3Context *q, GetBitContext *gb,
memset(snd->imdct_buf, 0, 512 * sizeof(*snd->imdct_buf));
/* gain compensation and overlapping */
- gain_compensate_and_overlap(snd->imdct_buf,
- &snd->prev_frame[band * 256],
- &output[band * 256],
- &gain1->g_block[band],
- &gain2->g_block[band]);
+ ff_atrac_gain_compensation(&q->gainc_ctx, snd->imdct_buf,
+ &snd->prev_frame[band * 256],
+ &gain1->g_block[band], &gain2->g_block[band],
+ 256, &output[band * 256]);
}
/* Swap the gain control buffers for the next frame. */
@@ -982,6 +918,7 @@ static av_cold int atrac3_decode_init(AVCodecContext *avctx)
q->matrix_coeff_index_next[i] = 3;
}
+ ff_atrac_init_gain_compensation(&q->gainc_ctx, 4, 3);
avpriv_float_dsp_init(&q->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
ff_fmt_convert_init(&q->fmt_conv, avctx);
More information about the ffmpeg-cvslog
mailing list