libavcodec/parser.c

   1 /*
   2  * Audio and Video frame extraction
   3  * Copyright (c) 2003 Fabrice Bellard.
   4  * Copyright (c) 2003 Michael Niedermayer.
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "parser.h"
  24
  25 AVCodecParser *av_first_parser = NULL;
  26
  27 AVCodecParser* av_parser_next(AVCodecParser *p){
  28     if(p) return p->next;
  29     else  return av_first_parser;
  30 }
  31
  32 void av_register_codec_parser(AVCodecParser *parser)
  33 {
  34     parser->next = av_first_parser;
  35     av_first_parser = parser;
  36 }
  37
  38 AVCodecParserContext *av_parser_init(int codec_id)
  39 {
  40     AVCodecParserContext *s;
  41     AVCodecParser *parser;
  42     int ret;
  43
  44     if(codec_id == CODEC_ID_NONE)
  45         return NULL;
  46
  47     for(parser = av_first_parser; parser != NULL; parser = parser->next) {
  48         if (parser->codec_ids[0] == codec_id ||
  49             parser->codec_ids[1] == codec_id ||
  50             parser->codec_ids[2] == codec_id ||
  51             parser->codec_ids[3] == codec_id ||
  52             parser->codec_ids[4] == codec_id)
  53             goto found;
  54     }
  55     return NULL;
  56  found:
  57     s = av_mallocz(sizeof(AVCodecParserContext));
  58     if (!s)
  59         return NULL;
  60     s->parser = parser;
  61     s->priv_data = av_mallocz(parser->priv_data_size);
  62     if (!s->priv_data) {
  63         av_free(s);
  64         return NULL;
  65     }
  66     if (parser->parser_init) {
  67         ret = parser->parser_init(s);
  68         if (ret != 0) {
  69             av_free(s->priv_data);
  70             av_free(s);
  71             return NULL;
  72         }
  73     }
  74     s->fetch_timestamp=1;
  75     s->pict_type = FF_I_TYPE;
  76     return s;
  77 }
  78
  79 /**
  80  *
  81  * @param buf           input
  82  * @param buf_size      input length, to signal EOF, this should be 0 (so that the last frame can be output)
  83  * @param pts           input presentation timestamp
  84  * @param dts           input decoding timestamp
  85  * @param poutbuf       will contain a pointer to the first byte of the output frame
  86  * @param poutbuf_size  will contain the length of the output frame
  87  * @return the number of bytes of the input bitstream used
  88  *
  89  * Example:
  90  * @code
  91  *   while(in_len){
  92  *       len = av_parser_parse(myparser, AVCodecContext, &data, &size,
  93  *                                       in_data, in_len,
  94  *                                       pts, dts);
  95  *       in_data += len;
  96  *       in_len  -= len;
  97  *
  98  *       if(size)
  99  *          decode_frame(data, size);
 100  *   }
 101  * @endcode
 102  */
 103 int av_parser_parse(AVCodecParserContext *s,
 104                     AVCodecContext *avctx,
 105                     uint8_t **poutbuf, int *poutbuf_size,
 106                     const uint8_t *buf, int buf_size,
 107                     int64_t pts, int64_t dts)
 108 {
 109     int index, i, k;
 110     uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];
 111
 112     if (buf_size == 0) {
 113         /* padding is always necessary even if EOF, so we add it here */
 114         memset(dummy_buf, 0, sizeof(dummy_buf));
 115         buf = dummy_buf;
 116     } else {
 117         /* add a new packet descriptor */
 118         k = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
 119         s->cur_frame_start_index = k;
 120         s->cur_frame_offset[k] = s->cur_offset;
 121         s->cur_frame_pts[k] = pts;
 122         s->cur_frame_dts[k] = dts;
 123
 124         /* fill first PTS/DTS */
 125         if (s->fetch_timestamp){
 126             s->fetch_timestamp=0;
 127             s->last_pts = pts;
 128             s->last_dts = dts;
 129             s->last_offset = 0;
 130             s->cur_frame_pts[k] =
 131             s->cur_frame_dts[k] = AV_NOPTS_VALUE;
 132         }
 133     }
 134
 135     /* WARNING: the returned index can be negative */
 136     index = s->parser->parser_parse(s, avctx, (const uint8_t **)poutbuf, poutbuf_size, buf, buf_size);
 137 //av_log(NULL, AV_LOG_DEBUG, "parser: in:%"PRId64", %"PRId64", out:%"PRId64", %"PRId64", in:%d out:%d id:%d\n", pts, dts, s->last_pts, s->last_dts, buf_size, *poutbuf_size, avctx->codec_id);
 138     /* update the file pointer */
 139     if (*poutbuf_size) {
 140         /* fill the data for the current frame */
 141         s->frame_offset = s->last_frame_offset;
 142         s->pts = s->last_pts;
 143         s->dts = s->last_dts;
 144         s->offset = s->last_offset;
 145
 146         /* offset of the next frame */
 147         s->last_frame_offset = s->cur_offset + index;
 148         /* find the packet in which the new frame starts. It
 149            is tricky because of MPEG video start codes
 150            which can begin in one packet and finish in
 151            another packet. In the worst case, an MPEG
 152            video start code could be in 4 different
 153            packets. */
 154         k = s->cur_frame_start_index;
 155         for(i = 0; i < AV_PARSER_PTS_NB; i++) {
 156             if (s->last_frame_offset >= s->cur_frame_offset[k])
 157                 break;
 158             k = (k - 1) & (AV_PARSER_PTS_NB - 1);
 159         }
 160
 161         s->last_pts = s->cur_frame_pts[k];
 162         s->last_dts = s->cur_frame_dts[k];
 163         s->last_offset = s->last_frame_offset - s->cur_frame_offset[k];
 164
 165         /* some parsers tell us the packet size even before seeing the first byte of the next packet,
 166            so the next pts/dts is in the next chunk */
 167         if(index == buf_size){
 168             s->fetch_timestamp=1;
 169         }
 170     }
 171     if (index < 0)
 172         index = 0;
 173     s->cur_offset += index;
 174     return index;
 175 }
 176
 177 /**
 178  *
 179  * @return 0 if the output buffer is a subset of the input, 1 if it is allocated and must be freed
 180  * @deprecated use AVBitstreamFilter
 181  */
 182 int av_parser_change(AVCodecParserContext *s,
 183                      AVCodecContext *avctx,
 184                      uint8_t **poutbuf, int *poutbuf_size,
 185                      const uint8_t *buf, int buf_size, int keyframe){
 186
 187     if(s && s->parser->split){
 188         if((avctx->flags & CODEC_FLAG_GLOBAL_HEADER) || (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)){
 189             int i= s->parser->split(avctx, buf, buf_size);
 190             buf += i;
 191             buf_size -= i;
 192         }
 193     }
 194
 195     /* cast to avoid warning about discarding qualifiers */
 196     *poutbuf= (uint8_t *) buf;
 197     *poutbuf_size= buf_size;
 198     if(avctx->extradata){
 199         if(  (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER))
 200             /*||(s->pict_type != I_TYPE && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_NOKEY))*/
 201             /*||(? && (s->flags & PARSER_FLAG_DUMP_EXTRADATA_AT_BEGIN)*/){
 202             int size= buf_size + avctx->extradata_size;
 203             *poutbuf_size= size;
 204             *poutbuf= av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
 205
 206             memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
 207             memcpy((*poutbuf) + avctx->extradata_size, buf, buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
 208             return 1;
 209         }
 210     }
 211
 212     return 0;
 213 }
 214
 215 void av_parser_close(AVCodecParserContext *s)
 216 {
 217     if (s->parser->parser_close)
 218         s->parser->parser_close(s);
 219     av_free(s->priv_data);
 220     av_free(s);
 221 }
 222
 223 /*****************************************************/
 224
 225 /**
 226  * combines the (truncated) bitstream to a complete frame
 227  * @returns -1 if no complete frame could be created
 228  */
 229 int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
 230 {
 231 #if 0
 232     if(pc->overread){
 233         printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
 234         printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);
 235     }
 236 #endif
 237
 238     /* Copy overread bytes from last frame into buffer. */
 239     for(; pc->overread>0; pc->overread--){
 240         pc->buffer[pc->index++]= pc->buffer[pc->overread_index++];
 241     }
 242
 243     /* flush remaining if EOF */
 244     if(!*buf_size && next == END_NOT_FOUND){
 245         next= 0;
 246     }
 247
 248     pc->last_index= pc->index;
 249
 250     /* copy into buffer end return */
 251     if(next == END_NOT_FOUND){
 252         pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, (*buf_size) + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
 253
 254         memcpy(&pc->buffer[pc->index], *buf, *buf_size);
 255         pc->index += *buf_size;
 256         return -1;
 257     }
 258
 259     *buf_size=
 260     pc->overread_index= pc->index + next;
 261
 262     /* append to buffer */
 263     if(pc->index){
 264         pc->buffer= av_fast_realloc(pc->buffer, &pc->buffer_size, next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
 265
 266         memcpy(&pc->buffer[pc->index], *buf, next + FF_INPUT_BUFFER_PADDING_SIZE );
 267         pc->index = 0;
 268         *buf= pc->buffer;
 269     }
 270
 271     /* store overread bytes */
 272     for(;next < 0; next++){
 273         pc->state = (pc->state<<8) | pc->buffer[pc->last_index + next];
 274         pc->overread++;
 275     }
 276
 277 #if 0
 278     if(pc->overread){
 279         printf("overread %d, state:%X next:%d index:%d o_index:%d\n", pc->overread, pc->state, next, pc->index, pc->overread_index);
 280         printf("%X %X %X %X\n", (*buf)[0], (*buf)[1],(*buf)[2],(*buf)[3]);
 281     }
 282 #endif
 283
 284     return 0;
 285 }
 286
 287 void ff_parse_close(AVCodecParserContext *s)
 288 {
 289     ParseContext *pc = s->priv_data;
 290
 291     av_free(pc->buffer);
 292 }
 293
 294 void ff_parse1_close(AVCodecParserContext *s)
 295 {
 296     ParseContext1 *pc1 = s->priv_data;
 297
 298     av_free(pc1->pc.buffer);
 299     av_free(pc1->enc);
 300 }
 301
 302 /*************************/
 303
 304 int ff_mpeg4video_split(AVCodecContext *avctx,
 305                            const uint8_t *buf, int buf_size)
 306 {
 307     int i;
 308     uint32_t state= -1;
 309
 310     for(i=0; i<buf_size; i++){
 311         state= (state<<8) | buf[i];
 312         if(state == 0x1B3 || state == 0x1B6)
 313             return i-3;
 314     }
 315     return 0;
 316 }