/* * H261 parser * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> * Copyright (c) 2004 Maarten Daniels * * This file is part of Libav. * * Libav 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, * 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 * 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; 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, };