1 /*
2 * Copyright (c) 2018 Paul B Mahol
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 #include "bsf.h"
22 #include "bsf_internal.h"
23 #include "get_bits.h"
24 #include "mlp_parse.h"
25 #include "mlp.h"
26
27 typedef struct AccessUnit {
28 uint8_t bits[4];
29 uint16_t offset;
30 uint16_t optional;
31 } AccessUnit;
32
33 typedef struct TrueHDCoreContext {
34 MLPHeaderInfo hdr;
35 } TrueHDCoreContext;
36
truehd_core_filter(AVBSFContext * ctx,AVPacket * pkt)37 static int truehd_core_filter(AVBSFContext *ctx, AVPacket *pkt)
38 {
39 TrueHDCoreContext *s = ctx->priv_data;
40 GetBitContext gbc;
41 AccessUnit units[MAX_SUBSTREAMS];
42 int ret, i, last_offset = 0;
43 int in_size, out_size;
44 int have_header = 0;
45 int substream_bytes = 0;
46 int end;
47
48 ret = ff_bsf_get_packet_ref(ctx, pkt);
49 if (ret < 0)
50 return ret;
51
52 if (pkt->size < 4) {
53 ret = AVERROR_INVALIDDATA;
54 goto fail;
55 }
56
57 in_size = (AV_RB16(pkt->data) & 0xFFF) * 2;
58 if (in_size < 4 || in_size > pkt->size) {
59 ret = AVERROR_INVALIDDATA;
60 goto fail;
61 }
62
63 ret = init_get_bits8(&gbc, pkt->data + 4, pkt->size - 4);
64 if (ret < 0)
65 goto fail;
66
67 if (show_bits_long(&gbc, 32) == 0xf8726fba) {
68 if ((ret = ff_mlp_read_major_sync(ctx, &s->hdr, &gbc)) < 0)
69 goto fail;
70 have_header = 1;
71 }
72
73 if (s->hdr.num_substreams > MAX_SUBSTREAMS) {
74 ret = AVERROR_INVALIDDATA;
75 goto fail;
76 }
77
78 for (i = 0; i < s->hdr.num_substreams; i++) {
79 for (int j = 0; j < 4; j++)
80 units[i].bits[j] = get_bits1(&gbc);
81
82 units[i].offset = get_bits(&gbc, 12);
83 if (i < 3) {
84 last_offset = units[i].offset * 2;
85 substream_bytes += 2;
86 }
87
88 if (units[i].bits[0]) {
89 units[i].optional = get_bits(&gbc, 16);
90 if (i < 3)
91 substream_bytes += 2;
92 }
93 }
94 end = get_bits_count(&gbc) >> 3;
95
96 out_size = end + 4 + last_offset;
97 if (out_size < in_size) {
98 int bpos = 0, reduce = end - have_header * 28 - substream_bytes;
99 uint16_t parity_nibble, dts = AV_RB16(pkt->data + 2);
100 uint16_t auheader;
101 uint8_t header[28];
102
103 av_assert1(reduce >= 0 && reduce % 2 == 0);
104
105 if (have_header) {
106 memcpy(header, pkt->data + 4, 28);
107 header[16] = (header[16] & 0x0c) | (FFMIN(s->hdr.num_substreams, 3) << 4);
108 header[17] &= 0x7f;
109 header[25] &= 0xfe;
110 AV_WL16(header + 26, ff_mlp_checksum16(header, 26));
111 }
112
113 pkt->data += reduce;
114 out_size -= reduce;
115 pkt->size = out_size;
116
117 ret = av_packet_make_writable(pkt);
118 if (ret < 0)
119 goto fail;
120
121 AV_WB16(pkt->data + 2, dts);
122 parity_nibble = dts;
123 parity_nibble ^= out_size / 2;
124
125 for (i = 0; i < FFMIN(s->hdr.num_substreams, 3); i++) {
126 uint16_t substr_hdr = 0;
127
128 substr_hdr |= (units[i].bits[0] << 15);
129 substr_hdr |= (units[i].bits[1] << 14);
130 substr_hdr |= (units[i].bits[2] << 13);
131 substr_hdr |= (units[i].bits[3] << 12);
132 substr_hdr |= units[i].offset;
133
134 AV_WB16(pkt->data + have_header * 28 + 4 + bpos, substr_hdr);
135
136 parity_nibble ^= substr_hdr;
137 bpos += 2;
138
139 if (units[i].bits[0]) {
140 AV_WB16(pkt->data + have_header * 28 + 4 + bpos, units[i].optional);
141
142 parity_nibble ^= units[i].optional;
143 bpos += 2;
144 }
145 }
146
147 parity_nibble ^= parity_nibble >> 8;
148 parity_nibble ^= parity_nibble >> 4;
149 parity_nibble &= 0xF;
150
151 auheader = (parity_nibble ^ 0xF) << 12;
152 auheader |= (out_size / 2) & 0x0fff;
153 AV_WB16(pkt->data, auheader);
154
155 if (have_header)
156 memcpy(pkt->data + 4, header, 28);
157 }
158
159 fail:
160 if (ret < 0)
161 av_packet_unref(pkt);
162
163 return ret;
164 }
165
truehd_core_flush(AVBSFContext * ctx)166 static void truehd_core_flush(AVBSFContext *ctx)
167 {
168 TrueHDCoreContext *s = ctx->priv_data;
169 memset(&s->hdr, 0, sizeof(s->hdr));
170 }
171
172 static const enum AVCodecID codec_ids[] = {
173 AV_CODEC_ID_TRUEHD, AV_CODEC_ID_NONE,
174 };
175
176 const AVBitStreamFilter ff_truehd_core_bsf = {
177 .name = "truehd_core",
178 .priv_data_size = sizeof(TrueHDCoreContext),
179 .filter = truehd_core_filter,
180 .flush = truehd_core_flush,
181 .codec_ids = codec_ids,
182 };
183