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 "mpeg4videodec.h"
30#if FF_API_FLAG_TRUNCATED
31/* Nuke this header when removing FF_API_FLAG_TRUNCATED */
32#include "mpeg4video_parser.h"
33#endif
34
35struct Mp4vParseContext {
36    ParseContext pc;
37    Mpeg4DecContext dec_ctx;
38    int first_picture;
39};
40
41#if FF_API_FLAG_TRUNCATED
42int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
43#else
44/**
45 * Find the end of the current frame in the bitstream.
46 * @return the position of the first byte of the next frame, or -1
47 */
48static int mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
49#endif
50{
51    int vop_found, i;
52    uint32_t state;
53
54    vop_found = pc->frame_start_found;
55    state     = pc->state;
56
57    i = 0;
58    if (!vop_found) {
59        for (i = 0; i < buf_size; i++) {
60            state = (state << 8) | buf[i];
61            if (state == VOP_STARTCODE) {
62                i++;
63                vop_found = 1;
64                break;
65            }
66        }
67    }
68
69    if (vop_found) {
70        /* EOF considered as end of frame */
71        if (buf_size == 0)
72            return 0;
73        for (; i < buf_size; i++) {
74            state = (state << 8) | buf[i];
75            if ((state & 0xFFFFFF00) == 0x100) {
76                if (state == SLICE_STARTCODE || state == EXT_STARTCODE)
77                    continue;
78                pc->frame_start_found = 0;
79                pc->state             = -1;
80                return i - 3;
81            }
82        }
83    }
84    pc->frame_start_found = vop_found;
85    pc->state             = state;
86    return END_NOT_FOUND;
87}
88
89/* XXX: make it use less memory */
90static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx,
91                               const uint8_t *buf, int buf_size)
92{
93    struct Mp4vParseContext *pc = s1->priv_data;
94    Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
95    MpegEncContext *s = &dec_ctx->m;
96    GetBitContext gb1, *gb = &gb1;
97    int ret;
98
99    s->avctx               = avctx;
100    s->current_picture_ptr = &s->current_picture;
101
102    if (avctx->extradata_size && pc->first_picture) {
103        init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
104        ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 1, 1);
105        if (ret < 0)
106            av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
107    }
108
109    init_get_bits(gb, buf, 8 * buf_size);
110    ret = ff_mpeg4_decode_picture_header(dec_ctx, gb, 0, 1);
111    if (s->width && (!avctx->width || !avctx->height ||
112                     !avctx->coded_width || !avctx->coded_height)) {
113        ret = ff_set_dimensions(avctx, s->width, s->height);
114        if (ret < 0)
115            return ret;
116    }
117    if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){
118        av_assert1(s1->pts == AV_NOPTS_VALUE);
119        av_assert1(s1->dts == AV_NOPTS_VALUE);
120
121        s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000});
122    }
123
124    s1->pict_type     = s->pict_type;
125    pc->first_picture = 0;
126    return ret;
127}
128
129static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
130{
131    struct Mp4vParseContext *pc = s->priv_data;
132
133    pc->first_picture           = 1;
134    pc->dec_ctx.m.quant_precision     = 5;
135    pc->dec_ctx.m.slice_context_count = 1;
136    pc->dec_ctx.showed_packed_warning = 1;
137    return 0;
138}
139
140static int mpeg4video_parse(AVCodecParserContext *s,
141                            AVCodecContext *avctx,
142                            const uint8_t **poutbuf, int *poutbuf_size,
143                            const uint8_t *buf, int buf_size)
144{
145    ParseContext *pc = s->priv_data;
146    int next;
147
148    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
149        next = buf_size;
150    } else {
151#if FF_API_FLAG_TRUNCATED
152        next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
153#else
154        next = mpeg4_find_frame_end(pc, buf, buf_size);
155#endif
156
157        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
158            *poutbuf      = NULL;
159            *poutbuf_size = 0;
160            return buf_size;
161        }
162    }
163    mpeg4_decode_header(s, avctx, buf, buf_size);
164
165    *poutbuf      = buf;
166    *poutbuf_size = buf_size;
167    return next;
168}
169
170const AVCodecParser ff_mpeg4video_parser = {
171    .codec_ids      = { AV_CODEC_ID_MPEG4 },
172    .priv_data_size = sizeof(struct Mp4vParseContext),
173    .parser_init    = mpeg4video_parse_init,
174    .parser_parse   = mpeg4video_parse,
175    .parser_close   = ff_parse_close,
176};
177