/*
  * H261 parser
  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
  * Copyright (c) 2004 Maarten Daniels
  *
  * This file is part of FFmpeg.
  *
  * 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.
  *
  * 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /**

  * @file

  * h261codec.
  */
 
 #include "parser.h"
 

 static int h261_find_frame_end(ParseContext *pc, AVCodecContext *avctx,
                                const uint8_t *buf, int buf_size)
 {

     int vop_found, i, j;
     uint32_t state;
 

     vop_found = pc->frame_start_found;
     state     = pc->state;

     for (i = 0; i < buf_size && !vop_found; i++) {
         state = (state << 8) | buf[i];
         for (j = 0; j < 8; j++) {
             if (((state >> j) & 0xFFFFF0) == 0x000100) {
                 vop_found = 1;

                 break;
             }
         }
     }

     if (vop_found) {
         for (; i < buf_size; i++) {
             state = (state << 8) | buf[i];
             for (j = 0; j < 8; j++) {
                 if (((state >> j) & 0xFFFFF0) == 0x000100) {
                     pc->frame_start_found = 0;
                     pc->state             = (state >> (3 * 8)) + 0xFF00;
                     return i - 2;

                 }
             }
         }
     }
 

     pc->frame_start_found = vop_found;
     pc->state             = state;

     return END_NOT_FOUND;
 }
 
 static int h261_parse(AVCodecParserContext *s,
                       AVCodecContext *avctx,

                       const uint8_t **poutbuf, int *poutbuf_size,

                       const uint8_t *buf, int buf_size)
 {
     ParseContext *pc = s->priv_data;
     int next;
 

     if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
         next = buf_size;
     } else {

         next = h261_find_frame_end(pc, avctx, buf, buf_size);

         if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

             *poutbuf      = NULL;

             *poutbuf_size = 0;
             return buf_size;
         }

     }

     *poutbuf      = buf;

     *poutbuf_size = buf_size;
     return next;
 }
 

 AVCodecParser ff_h261_parser = {

     .codec_ids      = { AV_CODEC_ID_H261 },

     .priv_data_size = sizeof(ParseContext),
     .parser_parse   = h261_parse,
     .parser_close   = ff_parse_close,

 };