147 lines
4.2 KiB
C
147 lines
4.2 KiB
C
/*
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* MPEG4 Video frame extraction
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* Copyright (c) 2003 Fabrice Bellard
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* Copyright (c) 2003 Michael Niedermayer
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*
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* This file is part of Libav.
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*
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* Libav 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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* Libav 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 Libav; 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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#include "internal.h"
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#include "parser.h"
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#include "mpegvideo.h"
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#include "mpeg4video.h"
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#include "mpeg4video_parser.h"
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struct Mp4vParseContext {
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ParseContext pc;
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struct MpegEncContext enc;
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int first_picture;
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};
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int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
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{
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int vop_found, i;
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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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i = 0;
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if (!vop_found) {
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for (i = 0; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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if (state == 0x1B6) {
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i++;
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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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/* EOF considered as end of frame */
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if (buf_size == 0)
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return 0;
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for (; i < buf_size; i++) {
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state = (state << 8) | buf[i];
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if ((state & 0xFFFFFF00) == 0x100) {
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pc->frame_start_found = 0;
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pc->state = -1;
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return i - 3;
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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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/* XXX: make it use less memory */
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static int av_mpeg4_decode_header(AVCodecParserContext *s1,
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AVCodecContext *avctx,
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const uint8_t *buf, int buf_size)
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{
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struct Mp4vParseContext *pc = s1->priv_data;
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MpegEncContext *s = &pc->enc;
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GetBitContext gb1, *gb = &gb1;
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int ret;
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s->avctx = avctx;
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s->current_picture_ptr = &s->current_picture;
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if (avctx->extradata_size && pc->first_picture) {
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init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
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ret = ff_mpeg4_decode_picture_header(s, gb);
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}
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init_get_bits(gb, buf, 8 * buf_size);
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ret = ff_mpeg4_decode_picture_header(s, gb);
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if (s->width && (!avctx->width || !avctx->height ||
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!avctx->coded_width || !avctx->coded_height)) {
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ret = ff_set_dimensions(avctx, s->width, s->height);
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if (ret < 0)
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return ret;
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}
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s1->pict_type = s->pict_type;
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pc->first_picture = 0;
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return ret;
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}
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static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
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{
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struct Mp4vParseContext *pc = s->priv_data;
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pc->first_picture = 1;
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pc->enc.slice_context_count = 1;
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return 0;
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}
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static int mpeg4video_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 = ff_mpeg4_find_frame_end(pc, 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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av_mpeg4_decode_header(s, avctx, buf, buf_size);
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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_mpeg4video_parser = {
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.codec_ids = { AV_CODEC_ID_MPEG4 },
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.priv_data_size = sizeof(struct Mp4vParseContext),
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.parser_init = mpeg4video_parse_init,
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.parser_parse = mpeg4video_parse,
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.parser_close = ff_parse_close,
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.split = ff_mpeg4video_split,
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};
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