2 * MPEG4 Video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
6 * This file is part of Libav.
8 * Libav is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * Libav is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with Libav; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 #include "mpegvideo.h"
26 #include "mpeg4video.h"
27 #include "mpeg4video_parser.h"
29 struct Mp4vParseContext {
31 Mpeg4DecContext dec_ctx;
35 int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
40 vop_found = pc->frame_start_found;
45 for (i = 0; i < buf_size; i++) {
46 state = (state << 8) | buf[i];
56 /* EOF considered as end of frame */
59 for (; i < buf_size; i++) {
60 state = (state << 8) | buf[i];
61 if ((state & 0xFFFFFF00) == 0x100) {
62 pc->frame_start_found = 0;
68 pc->frame_start_found = vop_found;
73 /* XXX: make it use less memory */
74 static int av_mpeg4_decode_header(AVCodecParserContext *s1,
75 AVCodecContext *avctx,
76 const uint8_t *buf, int buf_size)
78 struct Mp4vParseContext *pc = s1->priv_data;
79 Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
80 MpegEncContext *s = &dec_ctx->m;
81 GetBitContext gb1, *gb = &gb1;
85 s->current_picture_ptr = &s->current_picture;
87 if (avctx->extradata_size && pc->first_picture) {
88 init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
89 ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
92 init_get_bits(gb, buf, 8 * buf_size);
93 ret = ff_mpeg4_decode_picture_header(dec_ctx, gb);
94 if (s->width && (!avctx->width || !avctx->height ||
95 !avctx->coded_width || !avctx->coded_height)) {
96 ret = ff_set_dimensions(avctx, s->width, s->height);
100 s1->pict_type = s->pict_type;
101 pc->first_picture = 0;
105 static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
107 struct Mp4vParseContext *pc = s->priv_data;
109 pc->first_picture = 1;
110 pc->dec_ctx.m.slice_context_count = 1;
114 static int mpeg4video_parse(AVCodecParserContext *s,
115 AVCodecContext *avctx,
116 const uint8_t **poutbuf, int *poutbuf_size,
117 const uint8_t *buf, int buf_size)
119 ParseContext *pc = s->priv_data;
122 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
125 next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
127 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
133 av_mpeg4_decode_header(s, avctx, buf, buf_size);
136 *poutbuf_size = buf_size;
140 AVCodecParser ff_mpeg4video_parser = {
141 .codec_ids = { AV_CODEC_ID_MPEG4 },
142 .priv_data_size = sizeof(struct Mp4vParseContext),
143 .parser_init = mpeg4video_parse_init,
144 .parser_parse = mpeg4video_parse,
145 .parser_close = ff_parse_close,
146 .split = ff_mpeg4video_split,