[FFmpeg-cvslog] flacenc: use RICE2 entropy coding mode for 24-bit
Justin Ruggles
git at videolan.org
Mon Nov 5 23:20:51 CET 2012
ffmpeg | branch: master | Justin Ruggles <justin.ruggles at gmail.com> | Sat Oct 27 00:46:43 2012 -0400| [2e76f34387762405b79d2f7f26659826089c7275] | committer: Justin Ruggles
flacenc: use RICE2 entropy coding mode for 24-bit
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=2e76f34387762405b79d2f7f26659826089c7275
---
libavcodec/flacenc.c | 55 +++++++++++++++++++++++++++++++++++---------------
1 file changed, 39 insertions(+), 16 deletions(-)
diff --git a/libavcodec/flacenc.c b/libavcodec/flacenc.c
index b00df95..93d4646 100644
--- a/libavcodec/flacenc.c
+++ b/libavcodec/flacenc.c
@@ -43,7 +43,11 @@
#define MAX_PARTITIONS (1 << MAX_PARTITION_ORDER)
#define MAX_LPC_PRECISION 15
#define MAX_LPC_SHIFT 15
-#define MAX_RICE_PARAM 14
+
+enum CodingMode {
+ CODING_MODE_RICE = 4,
+ CODING_MODE_RICE2 = 5,
+};
typedef struct CompressionOptions {
int compression_level;
@@ -60,6 +64,7 @@ typedef struct CompressionOptions {
} CompressionOptions;
typedef struct RiceContext {
+ enum CodingMode coding_mode;
int porder;
int params[MAX_PARTITIONS];
} RiceContext;
@@ -435,8 +440,15 @@ static void init_frame(FlacEncodeContext *s, int nb_samples)
}
for (ch = 0; ch < s->channels; ch++) {
- frame->subframes[ch].wasted = 0;
- frame->subframes[ch].obits = s->avctx->bits_per_raw_sample;
+ FlacSubframe *sub = &frame->subframes[ch];
+
+ sub->wasted = 0;
+ sub->obits = s->avctx->bits_per_raw_sample;
+
+ if (sub->obits > 16)
+ sub->rc.coding_mode = CODING_MODE_RICE2;
+ else
+ sub->rc.coding_mode = CODING_MODE_RICE;
}
frame->verbatim_only = 0;
@@ -518,7 +530,7 @@ static uint64_t subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
part_end = psize;
for (p = 0; p < 1 << porder; p++) {
int k = sub->rc.params[p];
- count += 4;
+ count += sub->rc.coding_mode;
count += rice_count_exact(&sub->residual[i], part_end - i, k);
i = part_end;
part_end = FFMIN(s->frame.blocksize, part_end + psize);
@@ -534,7 +546,7 @@ static uint64_t subframe_count_exact(FlacEncodeContext *s, FlacSubframe *sub,
/**
* Solve for d/dk(rice_encode_count) = n-((sum-(n>>1))>>(k+1)) = 0.
*/
-static int find_optimal_param(uint64_t sum, int n)
+static int find_optimal_param(uint64_t sum, int n, int max_param)
{
int k;
uint64_t sum2;
@@ -543,7 +555,7 @@ static int find_optimal_param(uint64_t sum, int n)
return 0;
sum2 = sum - (n >> 1);
k = av_log2(av_clipl_int32(sum2 / n));
- return FFMIN(k, MAX_RICE_PARAM);
+ return FFMIN(k, max_param);
}
@@ -551,15 +563,17 @@ static uint64_t calc_optimal_rice_params(RiceContext *rc, int porder,
uint64_t *sums, int n, int pred_order)
{
int i;
- int k, cnt, part;
+ int k, cnt, part, max_param;
uint64_t all_bits;
+ max_param = (1 << rc->coding_mode) - 2;
+
part = (1 << porder);
all_bits = 4 * part;
cnt = (n >> porder) - pred_order;
for (i = 0; i < part; i++) {
- k = find_optimal_param(sums[i], cnt);
+ k = find_optimal_param(sums[i], cnt, max_param);
rc->params[i] = k;
all_bits += rice_encode_count(sums[i], cnt, k);
cnt = n >> porder;
@@ -612,6 +626,8 @@ static uint64_t calc_rice_params(RiceContext *rc, int pmin, int pmax,
assert(pmax >= 0 && pmax <= MAX_PARTITION_ORDER);
assert(pmin <= pmax);
+ tmp_rc.coding_mode = rc->coding_mode;
+
udata = av_malloc(n * sizeof(uint32_t));
for (i = 0; i < n; i++)
udata[i] = (2*data[i]) ^ (data[i]>>31);
@@ -650,7 +666,7 @@ static uint64_t find_subframe_rice_params(FlacEncodeContext *s,
int pmax = get_max_p_order(s->options.max_partition_order,
s->frame.blocksize, pred_order);
- uint64_t bits = 8 + pred_order * sub->obits + 2 + 4;
+ uint64_t bits = 8 + pred_order * sub->obits + 2 + sub->rc.coding_mode;
if (sub->type == FLAC_SUBFRAME_LPC)
bits += 4 + 5 + pred_order * s->options.lpc_coeff_precision;
bits += calc_rice_params(&sub->rc, pmin, pmax, sub->residual,
@@ -925,12 +941,18 @@ static void remove_wasted_bits(FlacEncodeContext *s)
sub->wasted = v;
sub->obits -= v;
+
+ /* for 24-bit, check if removing wasted bits makes the range better
+ suited for using RICE instead of RICE2 for entropy coding */
+ if (sub->obits <= 17)
+ sub->rc.coding_mode = CODING_MODE_RICE;
}
}
}
-static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
+static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n,
+ int max_rice_param)
{
int i, best;
int32_t lt, rt;
@@ -950,7 +972,7 @@ static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
}
/* estimate bit counts */
for (i = 0; i < 4; i++) {
- k = find_optimal_param(2 * sum[i], n);
+ k = find_optimal_param(2 * sum[i], n, max_rice_param);
sum[i] = rice_encode_count( 2 * sum[i], n, k);
}
@@ -989,9 +1011,10 @@ static void channel_decorrelation(FlacEncodeContext *s)
return;
}
- if (s->options.ch_mode < 0)
- frame->ch_mode = estimate_stereo_mode(left, right, n);
- else
+ if (s->options.ch_mode < 0) {
+ int max_rice_param = (1 << frame->subframes[0].rc.coding_mode) - 2;
+ frame->ch_mode = estimate_stereo_mode(left, right, n, max_rice_param);
+ } else
frame->ch_mode = s->options.ch_mode;
/* perform decorrelation and adjust bits-per-sample */
@@ -1100,7 +1123,7 @@ static void write_subframes(FlacEncodeContext *s)
}
/* rice-encoded block */
- put_bits(&s->pb, 2, 0);
+ put_bits(&s->pb, 2, sub->rc.coding_mode - 4);
/* partition order */
porder = sub->rc.porder;
@@ -1111,7 +1134,7 @@ static void write_subframes(FlacEncodeContext *s)
part_end = &sub->residual[psize];
for (p = 0; p < 1 << porder; p++) {
int k = sub->rc.params[p];
- put_bits(&s->pb, 4, k);
+ put_bits(&s->pb, sub->rc.coding_mode, k);
while (res < part_end)
set_sr_golomb_flac(&s->pb, *res++, k, INT32_MAX, 0);
part_end = FFMIN(frame_end, part_end + psize);
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