1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
|
/*
* RTP parser for VP9 payload format (draft version 0) - experimental
* Copyright (c) 2015 Thomas Volkert <thomas@homer-conferencing.com>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/intreadwrite.h"
#include "avio_internal.h"
#include "rtpdec_formats.h"
#define RTP_VP9_DESC_REQUIRED_SIZE 1
struct PayloadContext {
AVIOContext *buf;
uint32_t timestamp;
};
static av_cold int vp9_init(AVFormatContext *ctx, int st_index,
PayloadContext *data)
{
av_log(ctx, AV_LOG_WARNING,
"RTP/VP9 support is still experimental\n");
return 0;
}
static int vp9_handle_packet(AVFormatContext *ctx, PayloadContext *rtp_vp9_ctx,
AVStream *st, AVPacket *pkt, uint32_t *timestamp,
const uint8_t *buf, int len, uint16_t seq,
int flags)
{
int has_pic_id, has_layer_idc, has_ref_idc, has_ss_data, has_su_data;
av_unused int pic_id = 0, non_key_frame = 0;
av_unused int layer_temporal = -1, layer_spatial = -1, layer_quality = -1;
int ref_fields = 0, has_ref_field_ext_pic_id = 0;
int first_fragment, last_fragment;
int rtp_m;
int res = 0;
/* drop data of previous packets in case of non-continuous (lossy) packet stream */
if (rtp_vp9_ctx->buf && rtp_vp9_ctx->timestamp != *timestamp)
ffio_free_dyn_buf(&rtp_vp9_ctx->buf);
/* sanity check for size of input packet: 1 byte payload at least */
if (len < RTP_VP9_DESC_REQUIRED_SIZE + 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet, got %d bytes\n", len);
return AVERROR_INVALIDDATA;
}
/*
* decode the required VP9 payload descriptor according to section 4.2 of the spec.:
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* |I|L|F|B|E|V|U|-| (REQUIRED)
* +-+-+-+-+-+-+-+-+
*
* I: PictureID present
* L: Layer indices present
* F: Reference indices present
* B: Start of VP9 frame
* E: End of picture
* V: Scalability Structure (SS) present
* U: Scalability Structure Update (SU) present
*/
has_pic_id = !!(buf[0] & 0x80);
has_layer_idc = !!(buf[0] & 0x40);
has_ref_idc = !!(buf[0] & 0x20);
first_fragment = !!(buf[0] & 0x10);
last_fragment = !!(buf[0] & 0x08);
has_ss_data = !!(buf[0] & 0x04);
has_su_data = !!(buf[0] & 0x02);
rtp_m = !!(flags & RTP_FLAG_MARKER);
/* sanity check for markers: B should always be equal to the RTP M marker */
if (last_fragment != rtp_m) {
av_log(ctx, AV_LOG_ERROR, "Invalid combination of B and M marker (%d != %d)\n", last_fragment, rtp_m);
return AVERROR_INVALIDDATA;
}
/* pass the extensions field */
buf += RTP_VP9_DESC_REQUIRED_SIZE;
len -= RTP_VP9_DESC_REQUIRED_SIZE;
/*
* decode the 1-byte/2-byte picture ID:
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* I: |M|PICTURE ID | (RECOMMENDED)
* +-+-+-+-+-+-+-+-+
* M: | EXTENDED PID | (RECOMMENDED)
* +-+-+-+-+-+-+-+-+
*
* M: The most significant bit of the first octet is an extension flag.
* PictureID: 8 or 16 bits including the M bit.
*/
if (has_pic_id) {
/* check for 1-byte or 2-byte picture index */
if (buf[0] & 0x80) {
if (len < 2) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
pic_id = AV_RB16(buf) & 0x7fff;
buf += 2;
len -= 2;
} else {
pic_id = buf[0] & 0x7f;
buf++;
len--;
}
}
/*
* decode layer indices
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* L: | T | S | Q | R | (CONDITIONALLY RECOMMENDED)
* +-+-+-+-+-+-+-+-+
*
* T, S and Q are 2-bit indices for temporal, spatial, and quality layers.
* If "F" is set in the initial octet, R is 2 bits representing the number
* of reference fields this frame refers to.
*/
if (has_layer_idc) {
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
layer_temporal = buf[0] & 0xC0;
layer_spatial = buf[0] & 0x30;
layer_quality = buf[0] & 0x0C;
if (has_ref_idc) {
ref_fields = buf[0] & 0x03;
if (ref_fields)
non_key_frame = 1;
}
buf++;
len--;
}
/*
* decode the reference fields
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+ -\
* F: | PID |X| RS| RQ| (OPTIONAL) .
* +-+-+-+-+-+-+-+-+ . - R times
* X: | EXTENDED PID | (OPTIONAL) .
* +-+-+-+-+-+-+-+-+ -/
*
* PID: The relative Picture ID referred to by this frame.
* RS and RQ: The spatial and quality layer IDs.
* X: 1 if this layer index has an extended relative Picture ID.
*/
if (has_ref_idc) {
while (ref_fields) {
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
has_ref_field_ext_pic_id = buf[0] & 0x10;
/* pass ref. field */
if (has_ref_field_ext_pic_id) {
if (len < 2) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
/* ignore ref. data */
buf += 2;
len -= 2;
} else {
/* ignore ref. data */
buf++;
len--;
}
ref_fields--;
}
}
/*
* decode the scalability structure (SS)
*
* 0 1 2 3 4 5 6 7
* +-+-+-+-+-+-+-+-+
* V: | PATTERN LENGTH|
* +-+-+-+-+-+-+-+-+ -\
* | T | S | Q | R | (OPTIONAL) .
* +-+-+-+-+-+-+-+-+ -\ .
* | PID |X| RS| RQ| (OPTIONAL) . . - PAT. LEN. times
* +-+-+-+-+-+-+-+-+ . - R times .
* X: | EXTENDED PID | (OPTIONAL) . .
* +-+-+-+-+-+-+-+-+ -/ -/
*
* PID: The relative Picture ID referred to by this frame.
* RS and RQ: The spatial and quality layer IDs.
* X: 1 if this layer index has an extended relative Picture ID.
*/
if (has_ss_data) {
avpriv_report_missing_feature(ctx, "VP9 scalability structure data");
return AVERROR(ENOSYS);
}
/*
* decode the scalability update structure (SU)
*
* spec. is tbd
*/
if (has_su_data) {
avpriv_report_missing_feature(ctx, "VP9 scalability update structure data");
return AVERROR(ENOSYS);
}
/*
* decode the VP9 payload header
*
* spec. is tbd
*/
//XXX: implement when specified
/* sanity check: 1 byte payload as minimum */
if (len < 1) {
av_log(ctx, AV_LOG_ERROR, "Too short RTP/VP9 packet\n");
return AVERROR_INVALIDDATA;
}
/* start frame buffering with new dynamic buffer */
if (!rtp_vp9_ctx->buf) {
/* sanity check: a new frame should have started */
if (first_fragment) {
res = avio_open_dyn_buf(&rtp_vp9_ctx->buf);
if (res < 0)
return res;
/* update the timestamp in the frame packet with the one from the RTP packet */
rtp_vp9_ctx->timestamp = *timestamp;
} else {
/* frame not started yet, need more packets */
return AVERROR(EAGAIN);
}
}
/* write the fragment to the dyn. buffer */
avio_write(rtp_vp9_ctx->buf, buf, len);
/* do we need more fragments? */
if (!last_fragment)
return AVERROR(EAGAIN);
/* close frame buffering and create resulting A/V packet */
res = ff_rtp_finalize_packet(pkt, &rtp_vp9_ctx->buf, st->index);
if (res < 0)
return res;
return 0;
}
RTPDynamicProtocolHandler ff_vp9_dynamic_handler = {
.enc_name = "VP9",
.codec_type = AVMEDIA_TYPE_VIDEO,
.codec_id = AV_CODEC_ID_VP9,
.priv_data_size = sizeof(PayloadContext),
.init = vp9_init,
.parse_packet = vp9_handle_packet
};
|