1 // Copyright 2013 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #include "media/cast/rtp_receiver/rtp_parser/rtp_parser.h"
7 #include "base/logging.h"
8 #include "media/cast/cast_defines.h"
9 #include "media/cast/rtp_receiver/rtp_receiver.h"
10 #include "net/base/big_endian.h"
15 static const size_t kRtpCommonHeaderLength = 12;
16 static const size_t kRtpCastHeaderLength = 7;
17 static const uint8 kCastKeyFrameBitMask = 0x80;
18 static const uint8 kCastReferenceFrameIdBitMask = 0x40;
20 RtpParser::RtpParser(RtpData* incoming_payload_callback,
21 const RtpParserConfig parser_config)
22 : data_callback_(incoming_payload_callback),
23 parser_config_(parser_config) {
26 RtpParser::~RtpParser() {
29 bool RtpParser::ParsePacket(const uint8* packet, size_t length,
30 RtpCastHeader* rtp_header) {
31 if (length == 0) return false;
32 // Get RTP general header.
33 if (!ParseCommon(packet, length, rtp_header)) return false;
34 if (rtp_header->webrtc.header.payloadType == parser_config_.payload_type &&
35 rtp_header->webrtc.header.ssrc == parser_config_.ssrc) {
36 return ParseCast(packet + kRtpCommonHeaderLength,
37 length - kRtpCommonHeaderLength, rtp_header);
39 // Not a valid payload type / ssrc combination.
43 bool RtpParser::ParseCommon(const uint8* packet,
45 RtpCastHeader* rtp_header) {
46 if (length < kRtpCommonHeaderLength) return false;
47 uint8 version = packet[0] >> 6;
48 if (version != 2) return false;
49 uint8 cc = packet[0] & 0x0f;
50 bool marker = ((packet[1] & 0x80) != 0);
51 int payload_type = packet[1] & 0x7f;
53 uint16 sequence_number;
54 uint32 rtp_timestamp, ssrc;
55 net::BigEndianReader big_endian_reader(packet + 2, 10);
56 big_endian_reader.ReadU16(&sequence_number);
57 big_endian_reader.ReadU32(&rtp_timestamp);
58 big_endian_reader.ReadU32(&ssrc);
60 if (ssrc != parser_config_.ssrc) return false;
62 rtp_header->webrtc.header.markerBit = marker;
63 rtp_header->webrtc.header.payloadType = payload_type;
64 rtp_header->webrtc.header.sequenceNumber = sequence_number;
65 rtp_header->webrtc.header.timestamp = rtp_timestamp;
66 rtp_header->webrtc.header.ssrc = ssrc;
67 rtp_header->webrtc.header.numCSRCs = cc;
69 uint8 csrc_octs = cc * 4;
70 rtp_header->webrtc.type.Audio.numEnergy = rtp_header->webrtc.header.numCSRCs;
71 rtp_header->webrtc.header.headerLength = kRtpCommonHeaderLength + csrc_octs;
72 rtp_header->webrtc.type.Audio.isCNG = false;
73 rtp_header->webrtc.type.Audio.channel = parser_config_.audio_channels;
74 // TODO(pwestin): look at x bit and skip data.
78 bool RtpParser::ParseCast(const uint8* packet,
80 RtpCastHeader* rtp_header) {
81 if (length < kRtpCastHeaderLength) return false;
84 const uint8* data_ptr = packet;
85 size_t data_length = length;
86 rtp_header->is_key_frame = (data_ptr[0] & kCastKeyFrameBitMask);
87 rtp_header->is_reference = (data_ptr[0] & kCastReferenceFrameIdBitMask);
88 rtp_header->frame_id = data_ptr[1];
90 net::BigEndianReader big_endian_reader(data_ptr + 2, 4);
91 big_endian_reader.ReadU16(&rtp_header->packet_id);
92 big_endian_reader.ReadU16(&rtp_header->max_packet_id);
94 if (rtp_header->is_reference) {
95 rtp_header->reference_frame_id = data_ptr[6];
96 data_ptr += kRtpCastHeaderLength;
97 data_length -= kRtpCastHeaderLength;
99 data_ptr += kRtpCastHeaderLength - 1;
100 data_length -= kRtpCastHeaderLength - 1;
103 if (rtp_header->max_packet_id < rtp_header->packet_id) return false;
105 data_callback_->OnReceivedPayloadData(data_ptr, data_length, rtp_header);