1 /*
2 * QDesign Music 2 (QDM2) payload for RTP
3 * Copyright (c) 2010 Ronald S. Bultje
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 /**
23 * @file
24 * @brief RTP support for the QDM2 payload (todo: wiki)
25 * @author Ronald S. Bultje <rbultje@ronald.bitfreak.net>
26 */
27
28 #include <string.h>
35
37 /** values read from the config header, used as packet headers */
38 //@{
42 //@}
43
44 /** Temporary storage for superblock restoring, per packet ID (0x80 total) */
45 //@{
46 uint16_t
len[0x80];
///< how much the temporary buffer is filled
47 uint8_t
buf[0x80][0x800];
///< the temporary storage buffer
48
49 unsigned int cache;
///< number of data packets that we have cached right now
50 unsigned int n_pkts;
///< number of RTP packets received since last packet output / config
51 uint32_t
timestamp;
///< timestamp of next-to-be-returned packet
52 //@}
53 };
54
55 /**
56 * Parse configuration (basically the codec-specific extradata) from
57 * an RTP config subpacket (starts with 0xff).
58 *
59 * Layout of the config subpacket (in bytes):
60 * 1: 0xFF <- config ID
61 * then an array {
62 * 1: size <- of the current item
63 * 1: item type <- 0 .. 4
64 * size-2: data <- data depends on the item type
65 * }
66 *
67 * Item 0 implies the end of the config subpacket, and has no data.
68 * Item 1 implies a stream configuration without extradata.
69 * Item 2 max. nr. of subpackets per superblock
70 * Item 3 superblock type for the stream
71 * Item 4 implies a stream configuration with extradata (size >= 0x1c).
72 *
73 * @return <0 on error, otherwise the number of bytes parsed from the
74 * input buffer.
75 */
77 const uint8_t *buf, const uint8_t *end)
78 {
79 const uint8_t *p = buf;
81
82 while (end - p >= 2) {
83 unsigned int item_len = p[0], config_item = p[1];
84
85 if (item_len < 2 || end - p < item_len || config_item > 4)
87
88 switch (config_item) {
89 case 0: /* end of config block */
90 return p - buf + item_len;
91 case 1: /* stream without extradata */
92 /* FIXME: set default qdm->block_size */
93 break;
94 case 2: /**< subpackets per block */
95 if (item_len < 3)
98 break;
99 case 3: /* superblock type */
100 if (item_len < 4)
103 break;
104 case 4: /* stream with extradata */
105 if (item_len < 30)
107
111 }
120
122 break;
123 }
124
125 p += item_len;
126 }
127
128 return AVERROR(EAGAIN);
/* not enough data */
129 }
130
131 /**
132 * Parse a single subpacket. We store this subpacket in an intermediate
133 * buffer (position depends on the ID (byte[0]). When called, at least
134 * 4 bytes are available for reading (see qdm2_parse_packet()).
135 *
136 * Layout of a single subpacket (RTP packets commonly contain multiple
137 * such subpackets) - length in bytes:
138 * 1: ordering ID <- 0 .. 0x7F
139 * 1: subpacket type <- 0 .. 0x7F; value & 0x80 means subpacket length = 2 bytes, else 1 byte
140 * 1/2: subpacket length <- length of the data following the flags/length fields
141 * if (subpacket type & 0x7F) == 0x7F
142 * 1: subpacket type, higher bits
143 * size: subpacket data
144 *
145 * The subpackets come in randomly, and should be encapsulated into 1
146 * or more superblocks (containing qdm->subpkts_per_block subpackets
147 * each) per RTP packet, in order of ascending "ordering ID", see
148 * qdm2_restore_block().
149 *
150 * @return <0 on error, otherwise the number of bytes parsed from the
151 * input buffer.
152 */
154 const uint8_t *buf, const uint8_t *end)
155 {
156 const uint8_t *p = buf;
158
159 /* parse header so we know the size of the header/data */
160 id = *p++;
164 p += 2;
166 } else
168
169 if (end - p <
len + (
type == 0x7F) ||
id >= 0x80)
173
174 /* copy data into a temporary buffer */
175 to_copy =
FFMIN(
len + (p - &buf[1]), 0x800 - qdm->
len[
id]);
176 memcpy(&qdm->
buf[
id][qdm->
len[
id]], buf + 1, to_copy);
177 qdm->
len[
id] += to_copy;
178
179 return p +
len - buf;
180 }
181
182 /**
183 * Add a superblock header around a set of subpackets.
184 *
185 * @return <0 on error, else 0.
186 */
188 {
189 int to_copy, n, res, include_csum;
190 uint8_t *p, *csum_pos =
NULL;
191
192 /* create packet to hold subpkts into a superblock */
194 for (n = 0; n < 0x80; n++)
196 break;
198
200 return res;
204
205 /* superblock header */
206 if (qdm->
len[n] > 0xff) {
209 p += 2;
210 } else {
213 }
215 csum_pos = p;
216 p += 2;
217 }
218
219 /* subpacket data */
221 memcpy(p, qdm->
buf[n], to_copy);
223
224 /* checksum header */
225 if (include_csum) {
226 unsigned int total = 0;
227 uint8_t *q;
228
230 total += *q;
231 AV_WB16(csum_pos, (uint16_t) total);
232 }
233
234 return 0;
235 }
236
237 /** return 0 on packet, no more left, 1 on packet, -1 on partial packet... */
240 uint32_t *timestamp,
241 const uint8_t *buf,
int len, uint16_t seq,
243 {
245 const uint8_t *end = buf +
len, *p = buf;
246
250
251 /* configuration block */
252 if (*p == 0xff) {
255 "Out of sequence config - dropping queue\n");
257 memset(qdm->
len, 0,
sizeof(qdm->
len));
258 }
259
261 return res;
262 p += res;
263
264 /* We set codec_id to AV_CODEC_ID_NONE initially to
265 * delay decoder initialization since extradata is
266 * carried within the RTP stream, not SDP. Here,
267 * by setting codec_id to AV_CODEC_ID_QDM2, we are signalling
268 * to the decoder that it is OK to initialize. */
270 }
273
274 /* subpackets */
275 while (end - p >= 4) {
277 return res;
278 p += res;
279 }
280
285 for (n = 0; n < 0x80; n++)
288 }
289
290 /* output the subpackets into freshly created superblock structures */
292 return res;
293 if (--qdm->
cache == 0)
295
298
299 return (qdm->
cache > 0) ? 1 : 0;
300 }
301
308 };