1 /*
2 * HCOM audio decoder
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 "libavutil/intreadwrite.h"
22
23 #include "avcodec.h"
24 #include "codec_internal.h"
25 #include "get_bits.h"
26 #include "internal.h"
27
28 typedef struct HEntry {
29 int16_t l, r;
30 } HEntry;
31
32 typedef struct HCOMContext {
33 AVCodecContext *avctx;
34
35 uint8_t first_sample;
36 uint8_t sample;
37 int dict_entries;
38 int dict_entry;
39 int delta_compression;
40
41 HEntry *dict;
42 } HCOMContext;
43
hcom_init(AVCodecContext *avctx)44 static av_cold int hcom_init(AVCodecContext *avctx)
45 {
46 HCOMContext *s = avctx->priv_data;
47
48 if (avctx->ch_layout.nb_channels != 1) {
49 av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
50 return AVERROR_INVALIDDATA;
51 }
52
53 if (avctx->extradata_size <= 7)
54 return AVERROR_INVALIDDATA;
55 s->dict_entries = AV_RB16(avctx->extradata);
56 if (avctx->extradata_size < s->dict_entries * 4 + 7 ||
57 s->dict_entries == 0)
58 return AVERROR_INVALIDDATA;
59 s->delta_compression = AV_RB32(avctx->extradata + 2);
60 s->sample = s->first_sample = avctx->extradata[avctx->extradata_size - 1];
61
62 s->dict = av_calloc(s->dict_entries, sizeof(*s->dict));
63 if (!s->dict)
64 return AVERROR(ENOMEM);
65 for (int i = 0; i < s->dict_entries; i++) {
66 s->dict[i].l = AV_RB16(avctx->extradata + 6 + 4 * i);
67 s->dict[i].r = AV_RB16(avctx->extradata + 6 + 4 * i + 2);
68 if (s->dict[i].l >= 0 &&
69 (s->dict[i].l >= s->dict_entries ||
70 s->dict[i].r >= s->dict_entries ||
71 s->dict[i].r < 0 ))
72 return AVERROR_INVALIDDATA;
73 }
74 if (s->dict[0].l < 0)
75 return AVERROR_INVALIDDATA;
76
77 avctx->sample_fmt = AV_SAMPLE_FMT_U8;
78 s->dict_entry = 0;
79
80 return 0;
81 }
82
hcom_decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)83 static int hcom_decode(AVCodecContext *avctx, AVFrame *frame,
84 int *got_frame, AVPacket *pkt)
85 {
86 HCOMContext *s = avctx->priv_data;
87 GetBitContext gb;
88 int ret, n = 0;
89
90 if (pkt->size > INT16_MAX)
91 return AVERROR_INVALIDDATA;
92
93 frame->nb_samples = pkt->size * 8;
94 if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
95 return ret;
96
97 if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0)
98 return ret;
99
100 while (get_bits_left(&gb) > 0) {
101 if (get_bits1(&gb))
102 s->dict_entry = s->dict[s->dict_entry].r;
103 else
104 s->dict_entry = s->dict[s->dict_entry].l;
105
106 if (s->dict[s->dict_entry].l < 0) {
107 int16_t datum;
108
109 datum = s->dict[s->dict_entry].r;
110
111 if (!s->delta_compression)
112 s->sample = 0;
113 s->sample = (s->sample + datum) & 0xFF;
114
115 frame->data[0][n++] = s->sample;
116
117 s->dict_entry = 0;
118 }
119 }
120
121 frame->nb_samples = n;
122
123 *got_frame = 1;
124
125 return pkt->size;
126 }
127
hcom_close(AVCodecContext *avctx)128 static av_cold int hcom_close(AVCodecContext *avctx)
129 {
130 HCOMContext *s = avctx->priv_data;
131
132 av_freep(&s->dict);
133
134 return 0;
135 }
136
137 const FFCodec ff_hcom_decoder = {
138 .p.name = "hcom",
139 .p.long_name = NULL_IF_CONFIG_SMALL("HCOM Audio"),
140 .p.type = AVMEDIA_TYPE_AUDIO,
141 .p.id = AV_CODEC_ID_HCOM,
142 .priv_data_size = sizeof(HCOMContext),
143 .init = hcom_init,
144 .close = hcom_close,
145 FF_CODEC_DECODE_CB(hcom_decode),
146 .p.capabilities = AV_CODEC_CAP_DR1,
147 .caps_internal = FF_CODEC_CAP_INIT_THREADSAFE | FF_CODEC_CAP_INIT_CLEANUP,
148 };
149