1/*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19/**
20 * @file
21 * This bitstream filter splits VP9 superframes into packets containing
22 * just one frame.
23 */
24
25#include <stddef.h>
26
27#include "bsf.h"
28#include "bsf_internal.h"
29#include "bytestream.h"
30#include "get_bits.h"
31
32typedef struct VP9SFSplitContext {
33    AVPacket *buffer_pkt;
34
35    int nb_frames;
36    int next_frame;
37    size_t next_frame_offset;
38    int sizes[8];
39} VP9SFSplitContext;
40
41static int vp9_superframe_split_filter(AVBSFContext *ctx, AVPacket *out)
42{
43    VP9SFSplitContext *s = ctx->priv_data;
44    AVPacket *in;
45    int i, j, ret, marker;
46    int is_superframe = !!s->buffer_pkt->data;
47
48    if (!s->buffer_pkt->data) {
49        ret = ff_bsf_get_packet_ref(ctx, s->buffer_pkt);
50        if (ret < 0)
51            return ret;
52        in = s->buffer_pkt;
53
54        if (!in->size)
55            goto passthrough;
56
57        marker = in->data[in->size - 1];
58        if ((marker & 0xe0) == 0xc0) {
59            int length_size = 1 + ((marker >> 3) & 0x3);
60            int   nb_frames = 1 + (marker & 0x7);
61            int    idx_size = 2 + nb_frames * length_size;
62
63            if (in->size >= idx_size && in->data[in->size - idx_size] == marker) {
64                GetByteContext bc;
65                int64_t total_size = 0;
66
67                bytestream2_init(&bc, in->data + in->size + 1 - idx_size,
68                                 nb_frames * length_size);
69
70                for (i = 0; i < nb_frames; i++) {
71                    int frame_size = 0;
72                    for (j = 0; j < length_size; j++)
73                        frame_size |= bytestream2_get_byte(&bc) << (j * 8);
74
75                    total_size += frame_size;
76                    if (frame_size <= 0 || total_size > in->size - idx_size) {
77                        av_log(ctx, AV_LOG_ERROR,
78                               "Invalid frame size in a superframe: %d\n", frame_size);
79                        ret = AVERROR(EINVAL);
80                        goto fail;
81                    }
82                    s->sizes[i] = frame_size;
83                }
84                s->nb_frames         = nb_frames;
85                s->next_frame        = 0;
86                s->next_frame_offset = 0;
87                is_superframe        = 1;
88            }
89        }
90    }
91
92    if (is_superframe) {
93        GetBitContext gb;
94        int profile, invisible = 0;
95
96        ret = av_packet_ref(out, s->buffer_pkt);
97        if (ret < 0)
98            goto fail;
99
100        out->data += s->next_frame_offset;
101        out->size  = s->sizes[s->next_frame];
102
103        s->next_frame_offset += out->size;
104        s->next_frame++;
105
106        if (s->next_frame >= s->nb_frames)
107            av_packet_unref(s->buffer_pkt);
108
109        ret = init_get_bits8(&gb, out->data, out->size);
110        if (ret < 0)
111            goto fail;
112
113        get_bits(&gb, 2); // frame_marker
114        profile  = get_bits1(&gb);
115        profile |= get_bits1(&gb) << 1;
116        if (profile == 3)
117            get_bits1(&gb);
118        if (!get_bits1(&gb)) {
119            get_bits1(&gb);
120            invisible = !get_bits1(&gb);
121        }
122
123        if (invisible)
124            out->pts = AV_NOPTS_VALUE;
125
126    } else {
127passthrough:
128        av_packet_move_ref(out, s->buffer_pkt);
129    }
130
131    return 0;
132fail:
133    if (ret < 0)
134        av_packet_unref(out);
135    av_packet_unref(s->buffer_pkt);
136    return ret;
137}
138
139static int vp9_superframe_split_init(AVBSFContext *ctx)
140{
141    VP9SFSplitContext *s = ctx->priv_data;
142
143    s->buffer_pkt = av_packet_alloc();
144    if (!s->buffer_pkt)
145        return AVERROR(ENOMEM);
146
147    return 0;
148}
149
150static void vp9_superframe_split_flush(AVBSFContext *ctx)
151{
152    VP9SFSplitContext *s = ctx->priv_data;
153    av_packet_unref(s->buffer_pkt);
154}
155
156static void vp9_superframe_split_uninit(AVBSFContext *ctx)
157{
158    VP9SFSplitContext *s = ctx->priv_data;
159    av_packet_free(&s->buffer_pkt);
160}
161
162const FFBitStreamFilter ff_vp9_superframe_split_bsf = {
163    .p.name         = "vp9_superframe_split",
164    .p.codec_ids    = (const enum AVCodecID []){ AV_CODEC_ID_VP9, AV_CODEC_ID_NONE },
165    .priv_data_size = sizeof(VP9SFSplitContext),
166    .init           = vp9_superframe_split_init,
167    .flush          = vp9_superframe_split_flush,
168    .close          = vp9_superframe_split_uninit,
169    .filter         = vp9_superframe_split_filter,
170};
171