1 /*
2 * MPEG-4 video frame extraction
3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg 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.
12 *
13 * FFmpeg 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.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #define UNCHECKED_BITSTREAM_READER 1
24
25 #include "internal.h"
26 #include "parser.h"
27 #include "mpegvideo.h"
28 #include "mpeg4video.h"
29 #include "mpeg4video_parser.h"
30
31 struct Mp4vParseContext {
32 ParseContext pc;
33 Mpeg4DecContext dec_ctx;
34 int first_picture;
35 };
36
ff_mpeg4_find_frame_end(ParseContext * pc,const uint8_t * buf,int buf_size)37 int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
38 {
39 int vop_found, i;
40 uint32_t state;
41
42 vop_found = pc->frame_start_found;
43 state = pc->state;
44
45 i = 0;
46 if (!vop_found) {
47 for (i = 0; i < buf_size; i++) {
48 state = (state << 8) | buf[i];
49 if (state == VOP_STARTCODE) {
50 i++;
51 vop_found = 1;
52 break;
53 }
54 }
55 }
56
57 if (vop_found) {
58 /* EOF considered as end of frame */
59 if (buf_size == 0)
60 return 0;
61 for (; i < buf_size; i++) {
62 state = (state << 8) | buf[i];
63 if ((state & 0xFFFFFF00) == 0x100) {
64 if (state == SLICE_STARTCODE || state == EXT_STARTCODE)
65 continue;
66 pc->frame_start_found = 0;
67 pc->state = -1;
68 return i - 3;
69 }
70 }
71 }
72 pc->frame_start_found = vop_found;
73 pc->state = state;
74 return END_NOT_FOUND;
75 }
76
77 /* XXX: make it use less memory */
mpeg4_decode_header(AVCodecParserContext * s1,AVCodecContext * avctx,const uint8_t * buf,int buf_size)78 static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
79 const uint8_t *buf, int buf_size)
80 {
81 struct Mp4vParseContext *pc = s1->priv_data;
82 Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
83 MpegEncContext *s = &dec_ctx->m;
84 GetBitContext gb1, *gb = &gb1;
85 int ret;
86
87 s->avctx = avctx;
88 s->current_picture_ptr = &s->current_picture;
89
90 if (avctx->extradata_size && pc->first_picture) {
91 init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
92 ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 1);
93 if (ret < 0)
94 av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
95 }
96
97 init_get_bits(gb, buf, 8 * buf_size);
98 ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 0);
99 if (s->width && (!avctx->width || !avctx->height ||
100 !avctx->coded_width || !avctx->coded_height)) {
101 ret = ff_set_dimensions(avctx, s->width, s->height);
102 if (ret < 0)
103 return ret;
104 }
105 if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){
106 av_assert1(s1->pts == AV_NOPTS_VALUE);
107 av_assert1(s1->dts == AV_NOPTS_VALUE);
108
109 s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000});
110 }
111
112 s1->pict_type = s->pict_type;
113 pc->first_picture = 0;
114 return ret;
115 }
116
mpeg4video_parse_init(AVCodecParserContext * s)117 static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
118 {
119 struct Mp4vParseContext *pc = s->priv_data;
120
121 ff_mpeg4videodec_static_init();
122
123 pc->first_picture = 1;
124 pc->dec_ctx.m.quant_precision = 5;
125 pc->dec_ctx.m.slice_context_count = 1;
126 pc->dec_ctx.showed_packed_warning = 1;
127 return 0;
128 }
129
mpeg4video_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)130 static int mpeg4video_parse(AVCodecParserContext *s,
131 AVCodecContext *avctx,
132 const uint8_t **poutbuf, int *poutbuf_size,
133 const uint8_t *buf, int buf_size)
134 {
135 ParseContext *pc = s->priv_data;
136 int next;
137
138 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
139 next = buf_size;
140 } else {
141 next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
142
143 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
144 *poutbuf = NULL;
145 *poutbuf_size = 0;
146 return buf_size;
147 }
148 }
149 mpeg4_decode_header(s, avctx, buf, buf_size);
150
151 *poutbuf = buf;
152 *poutbuf_size = buf_size;
153 return next;
154 }
155
156 AVCodecParser ff_mpeg4video_parser = {
157 .codec_ids = { AV_CODEC_ID_MPEG4 },
158 .priv_data_size = sizeof(struct Mp4vParseContext),
159 .parser_init = mpeg4video_parse_init,
160 .parser_parse = mpeg4video_parse,
161 .parser_close = ff_parse_close,
162 .split = ff_mpeg4video_split,
163 };
164