• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright (C) 2019 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include <webrtc/VP8Packetizer.h>
18 
19 #include "Utils.h"
20 
21 #include <webrtc/RTPSocketHandler.h>
22 
23 #include <https/SafeCallbackable.h>
24 #include <https/Support.h>
25 
26 using namespace android;
27 
VP8Packetizer(std::shared_ptr<RunLoop> runLoop,std::shared_ptr<StreamingSource> frameBufferSource)28 VP8Packetizer::VP8Packetizer(
29         std::shared_ptr<RunLoop> runLoop,
30         std::shared_ptr<StreamingSource> frameBufferSource)
31     : Packetizer(runLoop, frameBufferSource) {
32 }
33 
packetize(const std::shared_ptr<SBuffer> & accessUnit,int64_t timeUs)34 void VP8Packetizer::packetize(const std::shared_ptr<SBuffer> &accessUnit, int64_t timeUs) {
35     static constexpr uint8_t PT = 96;
36     static constexpr uint32_t SSRC = 0xdeadbeef;
37 
38     // XXX Retransmission packets add 2 bytes (for the original seqNum), should
39     // probably reserve that amount in the original packets so we don't exceed
40     // the MTU on retransmission.
41     static const size_t kMaxSRTPPayloadSize =
42         RTPSocketHandler::kMaxUDPPayloadSize - SRTP_MAX_TRAILER_LEN;
43 
44     const uint8_t *src = accessUnit->data();
45     size_t srcSize = accessUnit->size();
46 
47     uint32_t rtpTime = ((timeUs - mediaStartTime()) * 9) / 100;
48 
49     LOG(VERBOSE) << "got accessUnit of size " << srcSize;
50 
51     size_t srcOffset = 0;
52     while (srcOffset < srcSize) {
53         size_t packetSize = 12;  // generic RTP header
54 
55         packetSize += 1;  // VP8 Payload Descriptor
56 
57         auto copy = std::min(srcSize - srcOffset, kMaxSRTPPayloadSize - packetSize);
58 
59         packetSize += copy;
60 
61         std::vector<uint8_t> packet(packetSize);
62         uint8_t *dst = packet.data();
63 
64         dst[0] = 0x80;
65 
66         dst[1] = PT;
67         if (srcOffset + copy == srcSize) {
68             dst[1] |= 0x80;  // (M)ark
69         }
70 
71         SET_U16(&dst[2], 0);  // seqNum
72         SET_U32(&dst[4], rtpTime);
73         SET_U32(&dst[8], SSRC);
74 
75         size_t dstOffset = 12;
76 
77         // VP8 Payload Descriptor
78         dst[dstOffset++] = (srcOffset == 0) ? 0x10 : 0x00;  // S
79 
80         memcpy(&dst[dstOffset], &src[srcOffset], copy);
81         dstOffset += copy;
82 
83         CHECK_EQ(dstOffset, packetSize);
84 
85         srcOffset += copy;
86 
87         queueRTPDatagram(&packet);
88     }
89 }
90 
rtpNow() const91 uint32_t VP8Packetizer::rtpNow() const {
92     return (timeSinceStart() * 90) / 1000;
93 }
94