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annotate libavcodec/h264_parser.c @ 3:0b056460c67d

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changed code to use VSs
author Nina Engelhardt <nengel@mailbox.tu-berlin.de>
date Mon, 29 Oct 2012 16:44:27 +0100
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nengel@2 1 /*
nengel@2 2 * H.26L/H.264/AVC/JVT/14496-10/... parser
nengel@2 3 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
nengel@2 4 *
nengel@2 5 * This file is part of FFmpeg.
nengel@2 6 *
nengel@2 7 * FFmpeg is free software; you can redistribute it and/or
nengel@2 8 * modify it under the terms of the GNU Lesser General Public
nengel@2 9 * License as published by the Free Software Foundation; either
nengel@2 10 * version 2.1 of the License, or (at your option) any later version.
nengel@2 11 *
nengel@2 12 * FFmpeg is distributed in the hope that it will be useful,
nengel@2 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
nengel@2 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
nengel@2 15 * Lesser General Public License for more details.
nengel@2 16 *
nengel@2 17 * You should have received a copy of the GNU Lesser General Public
nengel@2 18 * License along with FFmpeg; if not, write to the Free Software
nengel@2 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
nengel@2 20 */
nengel@2 21
nengel@2 22 /**
nengel@2 23 * @file
nengel@2 24 * H.264 / AVC / MPEG4 part10 parser.
nengel@2 25 * @author Michael Niedermayer <michaelni@gmx.at>
nengel@2 26 */
nengel@2 27
nengel@2 28 #include <unistd.h>
nengel@2 29
nengel@2 30 #include "golomb.h"
nengel@2 31 #include "libavutil/error.h"
nengel@2 32 #include "h264_types.h"
nengel@2 33
nengel@2 34 #undef NDEBUG
nengel@2 35 #include <assert.h>
nengel@2 36
nengel@2 37 #define END_NOT_FOUND (-100)
nengel@2 38
nengel@2 39 static int ff_h264_find_frame_end(ParserContext *s, const uint8_t *buf, int buf_size)
nengel@2 40 {
nengel@2 41 int i;
nengel@2 42 uint32_t state;
nengel@2 43
nengel@2 44 state= s->state;
nengel@2 45 if(state>13)
nengel@2 46 state= 7;
nengel@2 47
nengel@2 48 for(i=0; i<buf_size; i++){
nengel@2 49 if(state==7){
nengel@2 50 /* we check i<buf_size instead of i+3/7 because its simpler
nengel@2 51 * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end
nengel@2 52 */
nengel@2 53 while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))
nengel@2 54 i+=8;
nengel@2 55
nengel@2 56 for(; i<buf_size; i++){
nengel@2 57 if(!buf[i]){
nengel@2 58 state=2;
nengel@2 59 break;
nengel@2 60 }
nengel@2 61 }
nengel@2 62 }else if(state<=2){
nengel@2 63 if(buf[i]==1) state^= 5; //2->7, 1->4, 0->5
nengel@2 64 else if(buf[i]) state = 7;
nengel@2 65 else state>>=1; //2->1, 1->0, 0->0
nengel@2 66 }else if(state<=5){
nengel@2 67 int v= buf[i] & 0x1F;
nengel@2 68 if(v==6 || v==7 || v==8 || v==9){
nengel@2 69 if(s->frame_start_found){
nengel@2 70 i++;
nengel@2 71 goto found;
nengel@2 72 }
nengel@2 73 }else if(v==1 || v==2 || v==5){
nengel@2 74 if(s->frame_start_found){
nengel@2 75 state+=8;
nengel@2 76 continue;
nengel@2 77 }else
nengel@2 78 s->frame_start_found = 1;
nengel@2 79 }
nengel@2 80 state= 7;
nengel@2 81 }else{
nengel@2 82 if(buf[i] & 0x80)
nengel@2 83 goto found;
nengel@2 84 state= 7;
nengel@2 85 }
nengel@2 86 }
nengel@2 87 s->state= state;
nengel@2 88 return END_NOT_FOUND;
nengel@2 89
nengel@2 90 found:
nengel@2 91 s->state=7;
nengel@2 92 s->frame_start_found= 0;
nengel@2 93 return i-(state&5);
nengel@2 94 }
nengel@2 95
nengel@2 96 static int ff_combine_frame(ParserContext *s, GetBitContext *gb, int next, uint8_t **buf, int *buf_size)
nengel@2 97 {
nengel@2 98 int i;
nengel@2 99 /* Copy overread bytes from last frame into buffer. */
nengel@2 100 for(i =0; s->overread_cnt>0; s->overread_cnt--, i++){
nengel@2 101 gb->raw[s->index++]= s->overread[i];
nengel@2 102 }
nengel@2 103
nengel@2 104 /* EOF - END_NOT_FOUND means no next frame start is found in current partial read. If buf_size of the partial read is 0 we are at EOF */
nengel@2 105 if(!*buf_size && next == END_NOT_FOUND){
nengel@2 106 next= 0;
nengel@2 107 }
nengel@2 108 s->last_index= s->index;
nengel@2 109
nengel@2 110 /* copy into buffer end return */
nengel@2 111 if(next == END_NOT_FOUND){
nengel@2 112 gb->raw = av_fast_realloc(gb->raw, &gb->alloc_size, (*buf_size) + s->index + FF_INPUT_BUFFER_PADDING_SIZE);
nengel@2 113 memcpy(&gb->raw[s->index], *buf, *buf_size);
nengel@2 114 s->index += *buf_size;
nengel@2 115 return -1;
nengel@2 116 }
nengel@2 117
nengel@2 118 ///end found
nengel@2 119 *buf_size= s->index + next;
nengel@2 120 /* append to buffer */
nengel@2 121
nengel@2 122 gb->raw = av_fast_realloc(gb->raw, &gb->alloc_size, next + s->index + FF_INPUT_BUFFER_PADDING_SIZE);
nengel@2 123 memcpy(&gb->raw[s->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
nengel@2 124 s->index = 0;
nengel@2 125
nengel@2 126 /* store overread bytes */
nengel@2 127 for(i=0; next < 0; next++, i++){
nengel@2 128 s->state = (s->state<<8) | gb->raw[s->last_index + next];
nengel@2 129 s->overread[i] = gb->raw[s->last_index + next];
nengel@2 130 s->overread_cnt++;
nengel@2 131 }
nengel@2 132
nengel@2 133 return 0;
nengel@2 134 }
nengel@2 135
nengel@2 136 static int h264_parse(ParserContext *s, GetBitContext *gb,
nengel@2 137 uint8_t *buf, int buf_size)
nengel@2 138 {
nengel@2 139 int next;
nengel@2 140
nengel@2 141 next= ff_h264_find_frame_end(s, buf, buf_size);
nengel@2 142
nengel@2 143 if (ff_combine_frame(s, gb, next, &buf, &buf_size) < 0) {
nengel@2 144 gb->buf_size = 0;
nengel@2 145 return buf_size;
nengel@2 146 }
nengel@2 147
nengel@2 148 if(next<0 && next != END_NOT_FOUND){
nengel@2 149 assert(s->last_index + next >= 0 );
nengel@2 150 ff_h264_find_frame_end(s, &gb->raw[s->last_index + next], -next); //update state
nengel@2 151 }
nengel@2 152
nengel@2 153 gb->buf_size = buf_size;
nengel@2 154 return next;
nengel@2 155 }
nengel@2 156
nengel@2 157 static int ff_raw_read_partial_packet(ParserContext *pc)
nengel@2 158 {
nengel@2 159 int len= -1;
nengel@2 160
nengel@2 161 if (!pc->eof_reached){
nengel@2 162 len = read( pc->ifile, pc->data, pc->buffer_size);
nengel@2 163 // printf("read task %d\t%d\n", pc->ifile, len); fflush(NULL);
nengel@2 164 if (len < pc->buffer_size) {
nengel@2 165 pc->eof_reached = 1;
nengel@2 166 }
nengel@2 167 }
nengel@2 168
nengel@2 169 return len;
nengel@2 170 }
nengel@2 171
nengel@2 172 void av_read_frame_internal(ParserContext *pc, GetBitContext *gb){
nengel@2 173 int len;
nengel@2 174 uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE]={0};
nengel@2 175 av_fast_malloc(&gb->raw, &gb->alloc_size, 2048+FF_INPUT_BUFFER_PADDING_SIZE);
nengel@2 176
nengel@2 177 //Parsing is performed before read, since there are ussually leftovers from parsing the previous frame.
nengel@2 178 for(;;) {
nengel@2 179 if (pc->cur_len>0){
nengel@2 180 len = h264_parse(pc, gb, pc->cur_ptr, pc->cur_len);
nengel@2 181 if (len<0)
nengel@2 182 len =0;
nengel@2 183 //* increment read pointer */
nengel@2 184 pc->cur_ptr += len;
nengel@2 185 pc->cur_len -= len;
nengel@2 186
nengel@2 187 if (gb->buf_size) {
nengel@2 188 break;
nengel@2 189 }
nengel@2 190 }
nengel@2 191
nengel@2 192 //check for ret and not parser->eof_reached as one "read" can contain more than 1 frame
nengel@2 193 pc->size= ff_raw_read_partial_packet(pc);
nengel@2 194 if (pc->size < 0) {
nengel@2 195 pc->final_frame =1;
nengel@2 196 /* return the last frames, if any */
nengel@2 197 h264_parse(pc, gb, dummy_buf, 0);
nengel@2 198 break;
nengel@2 199 }
nengel@2 200 pc->cur_ptr = pc->data;
nengel@2 201 pc->cur_len = pc->size;
nengel@2 202 }
nengel@2 203
nengel@2 204 assert(gb->raw!=NULL);
nengel@2 205
nengel@2 206 }
nengel@2 207
nengel@2 208 ParserContext *get_parse_context(int ifile){
nengel@2 209 ParserContext *pc = av_mallocz(sizeof(ParserContext));
nengel@2 210 pc->buffer_size = 2048;
nengel@2 211 pc->final_frame = 0;
nengel@2 212 pc->cur_len= 0;
nengel@2 213 pc->data = av_mallocz(2048 + FF_INPUT_BUFFER_PADDING_SIZE);
nengel@2 214 pc->size = 2048;
nengel@2 215 pc->eof_reached =0;
nengel@2 216 pc->ifile = ifile;
nengel@2 217
nengel@2 218 return pc;
nengel@2 219 }
nengel@2 220
nengel@2 221 void free_parse_context(ParserContext *pc){
nengel@2 222 av_free(pc->data);
nengel@2 223 av_free(pc);
nengel@2 224 }