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-rw-r--r--libavcodec/cabac.c185
1 files changed, 179 insertions, 6 deletions
diff --git a/libavcodec/cabac.c b/libavcodec/cabac.c
index a96c9f5a2c..1a877dd2b5 100644
--- a/libavcodec/cabac.c
+++ b/libavcodec/cabac.c
@@ -2,20 +2,20 @@
* H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
- * This file is part of Libav.
+ * This file is part of FFmpeg.
*
- * Libav is free software; you can redistribute it and/or
+ * FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
- * Libav is distributed in the hope that it will be useful,
+ * FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
- * License along with Libav; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
@@ -27,6 +27,7 @@
#include <string.h>
#include "libavutil/common.h"
+#include "libavutil/timer.h"
#include "get_bits.h"
#include "cabac.h"
#include "cabac_functions.h"
@@ -160,7 +161,20 @@ const uint8_t ff_h264_cabac_tables[512 + 4*2*64 + 4*64 + 63] = {
/**
* @param buf_size size of buf in bits
*/
-void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
+void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){
+ init_put_bits(&c->pb, buf, buf_size);
+
+ c->low= 0;
+ c->range= 0x1FE;
+ c->outstanding_count= 0;
+ c->pb.bit_left++; //avoids firstBitFlag
+}
+
+/**
+ *
+ * @param buf_size size of buf in bits
+ */
+int ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
c->bytestream_start=
c->bytestream= buf;
c->bytestream_end= buf + buf_size;
@@ -168,9 +182,168 @@ void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){
#if CABAC_BITS == 16
c->low = (*c->bytestream++)<<18;
c->low+= (*c->bytestream++)<<10;
+ // Keep our fetches on a 2-byte boundry as this should avoid ever having to
+ // do unaligned loads if the compiler (or asm) optimises the double byte
+ // load into a single instruction
+ if(((uintptr_t)c->bytestream & 1) == 0) {
+ c->low += (1 << 9);
+ }
+ else {
+ c->low += ((*c->bytestream++) << 2) + 2;
+ }
#else
c->low = (*c->bytestream++)<<10;
-#endif
c->low+= ((*c->bytestream++)<<2) + 2;
+#endif
c->range= 0x1FE;
+ if ((c->range<<(CABAC_BITS+1)) < c->low)
+ return AVERROR_INVALIDDATA;
+ return 0;
}
+
+#ifdef TEST
+#define SIZE 10240
+
+#include "libavutil/lfg.h"
+#include "avcodec.h"
+
+static inline void put_cabac_bit(CABACContext *c, int b){
+ put_bits(&c->pb, 1, b);
+ for(;c->outstanding_count; c->outstanding_count--){
+ put_bits(&c->pb, 1, 1-b);
+ }
+}
+
+static inline void renorm_cabac_encoder(CABACContext *c){
+ while(c->range < 0x100){
+ //FIXME optimize
+ if(c->low<0x100){
+ put_cabac_bit(c, 0);
+ }else if(c->low<0x200){
+ c->outstanding_count++;
+ c->low -= 0x100;
+ }else{
+ put_cabac_bit(c, 1);
+ c->low -= 0x200;
+ }
+
+ c->range+= c->range;
+ c->low += c->low;
+ }
+}
+
+static void put_cabac(CABACContext *c, uint8_t * const state, int bit){
+ int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state];
+
+ if(bit == ((*state)&1)){
+ c->range -= RangeLPS;
+ *state = ff_h264_mlps_state[128 + *state];
+ }else{
+ c->low += c->range - RangeLPS;
+ c->range = RangeLPS;
+ *state= ff_h264_mlps_state[127 - *state];
+ }
+
+ renorm_cabac_encoder(c);
+}
+
+/**
+ * @param bit 0 -> write zero bit, !=0 write one bit
+ */
+static void put_cabac_bypass(CABACContext *c, int bit){
+ c->low += c->low;
+
+ if(bit){
+ c->low += c->range;
+ }
+//FIXME optimize
+ if(c->low<0x200){
+ put_cabac_bit(c, 0);
+ }else if(c->low<0x400){
+ c->outstanding_count++;
+ c->low -= 0x200;
+ }else{
+ put_cabac_bit(c, 1);
+ c->low -= 0x400;
+ }
+}
+
+/**
+ *
+ * @return the number of bytes written
+ */
+static int put_cabac_terminate(CABACContext *c, int bit){
+ c->range -= 2;
+
+ if(!bit){
+ renorm_cabac_encoder(c);
+ }else{
+ c->low += c->range;
+ c->range= 2;
+
+ renorm_cabac_encoder(c);
+
+ av_assert0(c->low <= 0x1FF);
+ put_cabac_bit(c, c->low>>9);
+ put_bits(&c->pb, 2, ((c->low>>7)&3)|1);
+
+ flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong
+ }
+
+ return (put_bits_count(&c->pb)+7)>>3;
+}
+
+int main(void){
+ CABACContext c;
+ uint8_t b[9*SIZE];
+ uint8_t r[9*SIZE];
+ int i, ret = 0;
+ uint8_t state[10]= {0};
+ AVLFG prng;
+
+ av_lfg_init(&prng, 1);
+ ff_init_cabac_encoder(&c, b, SIZE);
+
+ for(i=0; i<SIZE; i++){
+ if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7;
+ else r[i] = (i>>8)&1;
+ }
+
+ for(i=0; i<SIZE; i++){
+ put_cabac_bypass(&c, r[i]&1);
+ }
+
+ for(i=0; i<SIZE; i++){
+ put_cabac(&c, state, r[i]&1);
+ }
+
+ i= put_cabac_terminate(&c, 1);
+ b[i++] = av_lfg_get(&prng);
+ b[i ] = av_lfg_get(&prng);
+
+ ff_init_cabac_decoder(&c, b, SIZE);
+
+ memset(state, 0, sizeof(state));
+
+ for(i=0; i<SIZE; i++){
+ if( (r[i]&1) != get_cabac_bypass(&c) ) {
+ av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i);
+ ret = 1;
+ }
+ }
+
+ for(i=0; i<SIZE; i++){
+ if( (r[i]&1) != get_cabac_noinline(&c, state) ) {
+ av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i);
+ ret = 1;
+ }
+ }
+ if(!get_cabac_terminate(&c)) {
+ av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n");
+ ret = 1;
+ }
+
+ return ret;
+}
+
+#endif /* TEST */
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