libavcodec/dnxhd_parser.c

   1 /*
   2  * DNxHD/VC-3 parser
   3  * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * DNxHD/VC-3 parser
  25  */
  26
  27 #include "parser.h"
  28 #include "dnxhddata.h"
  29
  30 typedef struct {
  31     ParseContext pc;
  32     int cur_byte;
  33     int remaining;
  34     int w, h;
  35 } DNXHDParserContext;
  36
  37 static int dnxhd_find_frame_end(DNXHDParserContext *dctx,
  38                                 const uint8_t *buf, int buf_size)
  39 {
  40     ParseContext *pc = &dctx->pc;
  41     uint64_t state = pc->state64;
  42     int pic_found = pc->frame_start_found;
  43     int i = 0;
  44
  45     if (!pic_found) {
  46         for (i = 0; i < buf_size; i++) {
  47             state = (state << 8) | buf[i];
  48             if (ff_dnxhd_check_header_prefix(state & 0xffffffffff00LL) != 0) {
  49                 i++;
  50                 pic_found = 1;
  51                 dctx->cur_byte = 0;
  52                 dctx->remaining = 0;
  53                 break;
  54             }
  55         }
  56     }
  57
  58     if (pic_found && !dctx->remaining) {
  59         if (!buf_size) /* EOF considered as end of frame */
  60             return 0;
  61         for (; i < buf_size; i++) {
  62             dctx->cur_byte++;
  63             state = (state << 8) | buf[i];
  64
  65             if (dctx->cur_byte == 24) {
  66                 dctx->h = (state >> 32) & 0xFFFF;
  67             } else if (dctx->cur_byte == 26) {
  68                 dctx->w = (state >> 32) & 0xFFFF;
  69             } else if (dctx->cur_byte == 42) {
  70                 int cid = (state >> 32) & 0xFFFFFFFF;
  71                 int remaining;
  72
  73                 if (cid <= 0)
  74                     continue;
  75
  76                 remaining = ff_dnxhd_get_frame_size(cid);
  77                 if (remaining <= 0) {
  78                     remaining = ff_dnxhd_get_hr_frame_size(cid, dctx->w, dctx->h);
  79                     if (remaining <= 0)
  80                         continue;
  81                 }
  82                 remaining += i - 47;
  83                 dctx->remaining = remaining;
  84                 if (buf_size >= dctx->remaining) {
  85                     pc->frame_start_found = 0;
  86                     pc->state64 = -1;
  87                     dctx->cur_byte = 0;
  88                     dctx->remaining = 0;
  89                     return remaining;
  90                 } else {
  91                     dctx->remaining -= buf_size;
  92                     // Update variables for correctness, they are currently not used beyond here
  93                     state = -1;
  94                     dctx->cur_byte += buf_size - i;
  95                     break;
  96                 }
  97             }
  98         }
  99     } else if (pic_found) {
 100         if (dctx->remaining > buf_size) {
 101             dctx->remaining -= buf_size;
 102         } else {
 103             int remaining = dctx->remaining;
 104
 105             pc->frame_start_found = 0;
 106             pc->state64 = -1;
 107             dctx->cur_byte = 0;
 108             dctx->remaining = 0;
 109             return remaining;
 110         }
 111     }
 112     pc->frame_start_found = pic_found;
 113     pc->state64 = state;
 114     return END_NOT_FOUND;
 115 }
 116
 117 static int dnxhd_parse(AVCodecParserContext *s,
 118                        AVCodecContext *avctx,
 119                        const uint8_t **poutbuf, int *poutbuf_size,
 120                        const uint8_t *buf, int buf_size)
 121 {
 122     DNXHDParserContext *dctx = s->priv_data;
 123     ParseContext *pc = &dctx->pc;
 124     int next;
 125
 126     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
 127         next = buf_size;
 128     } else {
 129         next = dnxhd_find_frame_end(dctx, buf, buf_size);
 130         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
 131             *poutbuf      = NULL;
 132             *poutbuf_size = 0;
 133             return buf_size;
 134         }
 135     }
 136     *poutbuf      = buf;
 137     *poutbuf_size = buf_size;
 138     return next;
 139 }
 140
 141 const AVCodecParser ff_dnxhd_parser = {
 142     .codec_ids      = { AV_CODEC_ID_DNXHD },
 143     .priv_data_size = sizeof(DNXHDParserContext),
 144     .parser_parse   = dnxhd_parse,
 145     .parser_close   = ff_parse_close,
 146 };