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Use a custom radix sort implementation instead of qsort in dnxhd encoder.

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This is mainly to avoid test failures due to implementation-defined
behaviour of qsort when elements are equal, giving different results
for each of FreeBSD, Linux/glibc and Solaris.
In addition it is about 35 % faster, effect on overall speed is minimal
though (< 2%).
Regression tests are unchanged (i.e. identical to Linux/glibc).

Originally committed as revision 19949 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Reimar Döffinger 2009-09-21 10:28:31 +00:00
parent f5e82fec3d
commit 40e26453c4
1 changed files with 54 additions and 3 deletions
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57
libavcodec/dnxhdenc.c
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@ -651,9 +651,60 @@ static int dnxhd_find_qscale(DNXHDEncContext *ctx)
return 0;
}
static int dnxhd_rc_cmp(const void *a, const void *b)
#define BUCKET_BITS 8
#define RADIX_PASSES 4
#define NBUCKETS (1 << BUCKET_BITS)
static inline int get_bucket(int value, int shift)
{
return ((const RCCMPEntry *)b)->value - ((const RCCMPEntry *)a)->value;
value >>= shift;
value &= NBUCKETS - 1;
return NBUCKETS - 1 - value;
}
static void radix_count(const RCCMPEntry *data, int size, int buckets[RADIX_PASSES][NBUCKETS])
{
int i, j;
memset(buckets, 0, sizeof(buckets[0][0]) * RADIX_PASSES * NBUCKETS);
for (i = 0; i < size; i++) {
int v = data[i].value;
for (j = 0; j < RADIX_PASSES; j++) {
buckets[j][get_bucket(v, 0)]++;
v >>= BUCKET_BITS;
}
assert(!v);
}
for (j = 0; j < RADIX_PASSES; j++) {
int offset = size;
for (i = NBUCKETS - 1; i >= 0; i--)
buckets[j][i] = offset -= buckets[j][i];
assert(!buckets[j][0]);
}
}
static void radix_sort_pass(RCCMPEntry *dst, const RCCMPEntry *data, int size, int buckets[NBUCKETS], int pass)
{
int shift = pass * BUCKET_BITS;
int i;
for (i = 0; i < size; i++) {
int v = get_bucket(data[i].value, shift);
int pos = buckets[v]++;
dst[pos] = data[i];
}
}
static void radix_sort(RCCMPEntry *data, int size)
{
int buckets[RADIX_PASSES][NBUCKETS];
RCCMPEntry *tmp = av_malloc(sizeof(*tmp) * size);
radix_count(data, size, buckets);
radix_sort_pass(tmp, data, size, buckets[0], 0);
radix_sort_pass(data, tmp, size, buckets[1], 1);
if (buckets[2][NBUCKETS - 1] || buckets[3][NBUCKETS - 1]) {
radix_sort_pass(tmp, data, size, buckets[2], 2);
radix_sort_pass(data, tmp, size, buckets[3], 3);
}
av_free(tmp);
}
static int dnxhd_encode_fast(AVCodecContext *avctx, DNXHDEncContext *ctx)
@ -682,7 +733,7 @@ static int dnxhd_encode_fast(AVCodecContext *avctx, DNXHDEncContext *ctx)
if (!ret) {
if (RC_VARIANCE)
avctx->execute(avctx, dnxhd_mb_var_thread, (void**)&ctx->thread[0], NULL, avctx->thread_count, sizeof(void*));
qsort(ctx->mb_cmp, ctx->m.mb_num, sizeof(RCEntry), dnxhd_rc_cmp);
radix_sort(ctx->mb_cmp, ctx->m.mb_num);
for (x = 0; x < ctx->m.mb_num && max_bits > ctx->frame_bits; x++) {
int mb = ctx->mb_cmp[x].mb;
max_bits -= ctx->mb_rc[ctx->qscale][mb].bits - ctx->mb_rc[ctx->qscale+1][mb].bits;