path: root/libavformat/sdsdec.c (plain)
blob: 081bb4ca2d8740e73f1a747b69f7648087710862

1	/*
2	* MIDI Sample Dump Standard format demuxer
3	* Copyright (c) 2017 Paul B Mahol
4	*
5	* This file is part of FFmpeg.
6	*
7	* FFmpeg is free software; you can redistribute it and/or
8	* modify it under the terms of the GNU Lesser General Public
9	* License as published by the Free Software Foundation; either
10	* version 2.1 of the License, or (at your option) any later version.
11	*
12	* FFmpeg is distributed in the hope that it will be useful,
13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15	* Lesser General Public License for more details.
16	*
17	* You should have received a copy of the GNU Lesser General Public
18	* License along with FFmpeg; if not, write to the Free Software
19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20	*/
21
22	#include "libavutil/intreadwrite.h"
23	#include "avformat.h"
24	#include "internal.h"
25
26	typedef struct SDSContext {
27	uint8_t data[120];
28	int bit_depth;
29	int size;
30	void (*read_block)(const uint8_t *src, uint32_t *dst);
31	} SDSContext;
32
33	static int sds_probe(AVProbeData *p)
34	{
35	if (AV_RB32(p->buf) == 0xF07E0001 && p->buf[20] == 0xF7 &&
36	p->buf[6] >= 8 && p->buf[6] <= 28)
37	return AVPROBE_SCORE_EXTENSION;
38	return 0;
39	}
40
41	static void byte2_read(const uint8_t *src, uint32_t *dst)
42	{
43	int i;
44
45	for (i = 0; i < 120; i += 2) {
46	unsigned sample = (src[i + 0] << 25) + (src[i + 1] << 18);
47
48	dst[i / 2] = sample;
49	}
50	}
51
52	static void byte3_read(const uint8_t *src, uint32_t *dst)
53	{
54	int i;
55
56	for (i = 0; i < 120; i += 3) {
57	unsigned sample;
58
59	sample = (src[i + 0] << 25) | (src[i + 1] << 18) | (src[i + 2] << 11);
60	dst[i / 3] = sample;
61	}
62	}
63
64	static void byte4_read(const uint8_t *src, uint32_t *dst)
65	{
66	int i;
67
68	for (i = 0; i < 120; i += 4) {
69	unsigned sample;
70
71	sample = (src[i + 0] << 25) | (src[i + 1] << 18) | (src[i + 2] << 11) | (src[i + 3] << 4);
72	dst[i / 4] = sample;
73	}
74	}
75
76	#define SDS_3BYTE_TO_INT_DECODE(x) (((x) & 0x7F) | (((x) & 0x7F00) >> 1) | (((x) & 0x7F0000) >> 2))
77
78	static int sds_read_header(AVFormatContext *ctx)
79	{
80	SDSContext *s = ctx->priv_data;
81	unsigned sample_period;
82	AVIOContext *pb = ctx->pb;
83	AVStream *st;
84
85	st = avformat_new_stream(ctx, NULL);
86	if (!st)
87	return AVERROR(ENOMEM);
88
89	avio_skip(pb, 4);
90	avio_skip(pb, 2);
91
92	s->bit_depth = avio_r8(pb);
93	if (s->bit_depth < 8 || s->bit_depth > 28)
94	return AVERROR_INVALIDDATA;
95
96	if (s->bit_depth < 14) {
97	s->read_block = byte2_read;
98	s->size = 60 * 4;
99	} else if (s->bit_depth < 21) {
100	s->read_block = byte3_read;
101	s->size = 40 * 4;
102	} else {
103	s->read_block = byte4_read;
104	s->size = 30 * 4;
105	}
106	st->codecpar->codec_id = AV_CODEC_ID_PCM_U32LE;
107
108	sample_period = avio_rl24(pb);
109	sample_period = SDS_3BYTE_TO_INT_DECODE(sample_period);
110	avio_skip(pb, 11);
111
112	st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
113	st->codecpar->channels = 1;
114	st->codecpar->sample_rate = sample_period ? 1000000000 / sample_period : 16000;
115	st->duration = (avio_size(pb) - 21) / (127) * s->size / 4;
116
117	avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
118
119	return 0;
120	}
121
122	static int sds_read_packet(AVFormatContext *ctx, AVPacket *pkt)
123	{
124	SDSContext *s = ctx->priv_data;
125	AVIOContext *pb = ctx->pb;
126	int64_t pos;
127	int ret;
128
129	if (avio_feof(pb))
130	return AVERROR_EOF;
131
132	pos = avio_tell(pb);
133	if (avio_rb16(pb) != 0xF07E)
134	return AVERROR_INVALIDDATA;
135	avio_skip(pb, 3);
136
137	ret = av_new_packet(pkt, s->size);
138	if (ret < 0)
139	return ret;
140
141	ret = avio_read(pb, s->data, 120);
142
143	s->read_block(s->data, (uint32_t *)pkt->data);
144
145	avio_skip(pb, 1); // checksum
146	if (avio_r8(pb) != 0xF7)
147	return AVERROR_INVALIDDATA;
148
149	pkt->flags &= ~AV_PKT_FLAG_CORRUPT;
150	pkt->stream_index = 0;
151	pkt->pos = pos;
152
153	return ret;
154	}
155
156	AVInputFormat ff_sds_demuxer = {
157	.name = "sds",
158	.long_name = NULL_IF_CONFIG_SMALL("MIDI Sample Dump Standard"),
159	.priv_data_size = sizeof(SDSContext),
160	.read_probe = sds_probe,
161	.read_header = sds_read_header,
162	.read_packet = sds_read_packet,
163	.extensions = "sds",
164	.flags = AVFMT_GENERIC_INDEX,
165	};
166