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better lambda search method 

Originally committed as revision 10697 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Baptiste Coudurier 2007-10-09 14:15:03 +00:00
parent d6c52130f7
commit 45b8e9e507
1 changed files with 25 additions and 14 deletions
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39
libavcodec/dnxhdenc.c
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@ -573,27 +573,23 @@ static int dnxhd_mb_var_thread(AVCodecContext *avctx, void *arg)
static int dnxhd_encode_rdo(AVCodecContext *avctx, DNXHDEncContext *ctx)
{
unsigned lambda, up_lambda, down_lambda;
int lambda, up_step, down_step;
int last_lower = INT_MAX, last_higher = 0;
int x, y, q;
for (q = 1; q < avctx->qmax; q++) {
ctx->qscale = q;
avctx->execute(avctx, dnxhd_calc_bits_thread, (void**)&ctx->thread[0], NULL, avctx->thread_count);
}
up_lambda = avctx->qmax<<LAMBDA_FRAC_BITS;
down_lambda = 1; // higher ?
up_step = down_step = 2<<LAMBDA_FRAC_BITS;
lambda = ctx->lambda;
for (;;) {
int bits = 0;
int end = 0;
if (lambda == up_lambda) {
lambda--;
end = 1; // need to set final qscales/bits
}
if (lambda == down_lambda) {
if (lambda == last_higher) {
lambda++;
end = 1;
end = 1; // need to set final qscales/bits
}
for (y = 0; y < ctx->m.mb_height; y++) {
for (x = 0; x < ctx->m.mb_width; x++) {
@ -615,20 +611,35 @@ static int dnxhd_encode_rdo(AVCodecContext *avctx, DNXHDEncContext *ctx)
if (bits > ctx->frame_bits)
break;
}
//dprintf(ctx->m.avctx, "lambda %d, up %d, down %d, bits %d, frame %d\n", lambda, up_lambda, down_lambda, bits, ctx->frame_bits);
//dprintf(ctx->m.avctx, "lambda %d, up %u, down %u, bits %d, frame %d\n",
// lambda, last_higher, last_lower, bits, ctx->frame_bits);
if (end) {
if (bits > ctx->frame_bits)
return -1;
break;
}
if (bits < ctx->frame_bits) {
up_lambda = lambda;
lambda = (down_lambda+lambda)>>1;
last_lower = FFMIN(lambda, last_lower);
if (last_higher != 0)
lambda = (lambda+last_higher)>>1;
else
lambda -= down_step;
down_step *= 5; // XXX tune ?
up_step = 1<<LAMBDA_FRAC_BITS;
lambda = FFMAX(1, lambda);
if (lambda == last_lower)
break;
} else {
down_lambda = lambda;
lambda = (up_lambda+lambda)>>1;
last_higher = FFMAX(lambda, last_higher);
if (last_lower != INT_MAX)
lambda = (lambda+last_lower)>>1;
else
lambda += up_step;
up_step *= 5;
down_step = 1<<LAMBDA_FRAC_BITS;
}
}
//dprintf(ctx->m.avctx, "out lambda %d\n", lambda);
ctx->lambda = lambda;
return 0;
}