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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "media/cast/rtp_receiver/rtp_parser/rtp_parser.h"
#include "base/logging.h"
#include "media/cast/cast_defines.h"
#include "media/cast/rtp_receiver/rtp_receiver.h"
#include "net/base/big_endian.h"
namespace media {
namespace cast {
static const size_t kRtpCommonHeaderLength = 12;
static const size_t kRtpCastHeaderLength = 7;
static const uint8 kCastKeyFrameBitMask = 0x80;
static const uint8 kCastReferenceFrameIdBitMask = 0x40;
RtpParser::RtpParser(RtpData* incoming_payload_callback,
const RtpParserConfig parser_config)
: data_callback_(incoming_payload_callback),
parser_config_(parser_config) {
}
RtpParser::~RtpParser() {
}
bool RtpParser::ParsePacket(const uint8* packet, size_t length,
RtpCastHeader* rtp_header) {
if (length == 0) return false;
// Get RTP general header.
if (!ParseCommon(packet, length, rtp_header)) return false;
if (rtp_header->webrtc.header.payloadType == parser_config_.payload_type &&
rtp_header->webrtc.header.ssrc == parser_config_.ssrc) {
return ParseCast(packet + kRtpCommonHeaderLength,
length - kRtpCommonHeaderLength, rtp_header);
}
// Not a valid payload type / ssrc combination.
return false;
}
bool RtpParser::ParseCommon(const uint8* packet,
size_t length,
RtpCastHeader* rtp_header) {
if (length < kRtpCommonHeaderLength) return false;
uint8 version = packet[0] >> 6;
if (version != 2) return false;
uint8 cc = packet[0] & 0x0f;
bool marker = ((packet[1] & 0x80) != 0);
int payload_type = packet[1] & 0x7f;
uint16 sequence_number;
uint32 rtp_timestamp, ssrc;
net::BigEndianReader big_endian_reader(packet + 2, 10);
big_endian_reader.ReadU16(&sequence_number);
big_endian_reader.ReadU32(&rtp_timestamp);
big_endian_reader.ReadU32(&ssrc);
if (ssrc != parser_config_.ssrc) return false;
rtp_header->webrtc.header.markerBit = marker;
rtp_header->webrtc.header.payloadType = payload_type;
rtp_header->webrtc.header.sequenceNumber = sequence_number;
rtp_header->webrtc.header.timestamp = rtp_timestamp;
rtp_header->webrtc.header.ssrc = ssrc;
rtp_header->webrtc.header.numCSRCs = cc;
uint8 csrc_octs = cc * 4;
rtp_header->webrtc.type.Audio.numEnergy = rtp_header->webrtc.header.numCSRCs;
rtp_header->webrtc.header.headerLength = kRtpCommonHeaderLength + csrc_octs;
rtp_header->webrtc.type.Audio.isCNG = false;
rtp_header->webrtc.type.Audio.channel = parser_config_.audio_channels;
// TODO(pwestin): look at x bit and skip data.
return true;
}
bool RtpParser::ParseCast(const uint8* packet,
size_t length,
RtpCastHeader* rtp_header) {
if (length < kRtpCastHeaderLength) return false;
// Extract header.
const uint8* data_ptr = packet;
size_t data_length = length;
rtp_header->is_key_frame = (data_ptr[0] & kCastKeyFrameBitMask);
rtp_header->is_reference = (data_ptr[0] & kCastReferenceFrameIdBitMask);
rtp_header->frame_id = data_ptr[1];
net::BigEndianReader big_endian_reader(data_ptr + 2, 4);
big_endian_reader.ReadU16(&rtp_header->packet_id);
big_endian_reader.ReadU16(&rtp_header->max_packet_id);
if (rtp_header->is_reference) {
rtp_header->reference_frame_id = data_ptr[6];
data_ptr += kRtpCastHeaderLength;
data_length -= kRtpCastHeaderLength;
} else {
data_ptr += kRtpCastHeaderLength - 1;
data_length -= kRtpCastHeaderLength - 1;
}
if (rtp_header->max_packet_id < rtp_header->packet_id) return false;
data_callback_->OnReceivedPayloadData(data_ptr, data_length, rtp_header);
return true;
}
} // namespace cast
} // namespace media
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