mirror of https://git.ffmpeg.org/ffmpeg.git
95 lines
2.8 KiB
C
95 lines
2.8 KiB
C
/*
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* H.261 parser
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* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
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* Copyright (c) 2004 Maarten Daniels
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* H.261 parser
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*/
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#include "parser.h"
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static int h261_find_frame_end(ParseContext *pc, AVCodecContext *avctx,
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const uint8_t *buf, int buf_size)
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{
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int vop_found, i, j;
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uint32_t state;
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vop_found = pc->frame_start_found;
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state = pc->state;
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for (i = 0; i < buf_size && !vop_found; i++) {
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state = (state << 8) | buf[i];
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for (j = 0; j < 8; j++) {
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if (((state >> j) & 0xFFFFF0) == 0x000100) {
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vop_found = 1;
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break;
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}
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}
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}
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if (vop_found) {
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for (; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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for (j = 0; j < 8; j++) {
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if (((state >> j) & 0xFFFFF0) == 0x000100) {
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pc->frame_start_found = 0;
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pc->state = (state >> (3 * 8)) + 0xFF00;
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return i - 2;
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}
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}
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}
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}
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pc->frame_start_found = vop_found;
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pc->state = state;
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return END_NOT_FOUND;
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}
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static int h261_parse(AVCodecParserContext *s,
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AVCodecContext *avctx,
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const uint8_t **poutbuf, int *poutbuf_size,
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const uint8_t *buf, int buf_size)
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{
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ParseContext *pc = s->priv_data;
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int next;
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if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
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next = buf_size;
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} else {
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next = h261_find_frame_end(pc, avctx, buf, buf_size);
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if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
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*poutbuf = NULL;
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*poutbuf_size = 0;
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return buf_size;
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}
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}
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*poutbuf = buf;
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*poutbuf_size = buf_size;
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return next;
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}
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AVCodecParser ff_h261_parser = {
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.codec_ids = { AV_CODEC_ID_H261 },
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.priv_data_size = sizeof(ParseContext),
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.parser_parse = h261_parse,
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.parser_close = ff_parse_close,
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};
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