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flacenc: remove wasted trailing 0 bits

This commit is contained in:
Justin Ruggles 2012-10-25 15:07:59 -04:00
parent dfde8a34e5
commit e783316322
1 changed files with 37 additions and 2 deletions
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39
libavcodec/flacenc.c
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@ -20,6 +20,7 @@
*/ */
#include "libavutil/crc.h" #include "libavutil/crc.h"
#include "libavutil/intmath.h"
#include "libavutil/md5.h" #include "libavutil/md5.h"
#include "libavutil/opt.h" #include "libavutil/opt.h"
#include "avcodec.h" #include "avcodec.h"
@ -66,6 +67,7 @@ typedef struct FlacSubframe {
int type; int type;
int type_code; int type_code;
int obits; int obits;
int wasted;
int order; int order;
int32_t coefs[MAX_LPC_ORDER]; int32_t coefs[MAX_LPC_ORDER];
int shift; int shift;
@ -416,8 +418,10 @@ static void init_frame(FlacEncodeContext *s, int nb_samples)
} }
} }
for (ch = 0; ch < s->channels; ch++) for (ch = 0; ch < s->channels; ch++) {
frame->subframes[ch].wasted = 0;
frame->subframes[ch].obits = 16; frame->subframes[ch].obits = 16;
}
frame->verbatim_only = 0; frame->verbatim_only = 0;
} }
@ -972,6 +976,33 @@ static int encode_frame(FlacEncodeContext *s)
} }
static void remove_wasted_bits(FlacEncodeContext *s)
{
int ch, i;
for (ch = 0; ch < s->channels; ch++) {
FlacSubframe *sub = &s->frame.subframes[ch];
int32_t v = 0;
for (i = 0; i < s->frame.blocksize; i++) {
v |= sub->samples[i];
if (v & 1)
break;
}
if (v && !(v & 1)) {
v = av_ctz(v);
for (i = 0; i < s->frame.blocksize; i++)
sub->samples[i] >>= v;
sub->wasted = v;
sub->obits -= v;
}
}
}
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 i, best; int i, best;
@ -1117,7 +1148,9 @@ static void write_subframes(FlacEncodeContext *s)
/* subframe header */ /* subframe header */
put_bits(&s->pb, 1, 0); put_bits(&s->pb, 1, 0);
put_bits(&s->pb, 6, sub->type_code); put_bits(&s->pb, 6, sub->type_code);
put_bits(&s->pb, 1, 0); /* no wasted bits */ put_bits(&s->pb, 1, !!sub->wasted);
if (sub->wasted)
put_bits(&s->pb, sub->wasted, 1);
/* subframe */ /* subframe */
if (sub->type == FLAC_SUBFRAME_CONSTANT) { if (sub->type == FLAC_SUBFRAME_CONSTANT) {
@ -1235,6 +1268,8 @@ static int flac_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
channel_decorrelation(s); channel_decorrelation(s);
remove_wasted_bits(s);
frame_bytes = encode_frame(s); frame_bytes = encode_frame(s);
/* fallback to verbatim mode if the compressed frame is larger than it /* fallback to verbatim mode if the compressed frame is larger than it