How to implement custom frame encryptor in Android?

[Ivan Hutomo]

Hi, I tried to implement FakeFrameEncryptor in webrtc android based on the example from rtp_sender_receiver_unittest.cc? I tried to implement it in peer_connection.cc as shown below:

RTCErrorOr<rtc::scoped_refptr<RtpTransceiverInterface>>

PeerConnection::AddTransceiver(

cricket::MediaType media_type,

rtc::scoped_refptr<MediaStreamTrackInterface> track,

const RtpTransceiverInit& init,

bool update_negotiation_needed) {

RTC_DCHECK_RUN_ON(signaling_thread());

RTC_DCHECK((media_type == cricket::MEDIA_TYPE_AUDIO ||

media_type == cricket::MEDIA_TYPE_VIDEO));

if (track) {

RTC_DCHECK_EQ(media_type,

(track->kind() == MediaStreamTrackInterface::kAudioKind

? cricket::MEDIA_TYPE_AUDIO

: cricket::MEDIA_TYPE_VIDEO));

}

RTC_HISTOGRAM_COUNTS_LINEAR(kSimulcastNumberOfEncodings,

init.send_encodings.size(), 0, 7, 8);

size_t num_rids = absl::c_count_if(init.send_encodings,

[](const RtpEncodingParameters& encoding) {

return !encoding.rid.empty();

});

if (num_rids > 0 && num_rids != init.send_encodings.size()) {

LOG_AND_RETURN_ERROR(

RTCErrorType::INVALID_PARAMETER,

"RIDs must be provided for either all or none of the send encodings.");

}

if (num_rids > 0 && absl::c_any_of(init.send_encodings,

[](const RtpEncodingParameters& encoding) {

return !IsLegalRsidName(encoding.rid);

})) {

LOG_AND_RETURN_ERROR(RTCErrorType::INVALID_PARAMETER,

"Invalid RID value provided.");

}

if (absl::c_any_of(init.send_encodings,

[](const RtpEncodingParameters& encoding) {

return encoding.ssrc.has_value();

})) {

LOG_AND_RETURN_ERROR(

RTCErrorType::UNSUPPORTED_PARAMETER,

"Attempted to set an unimplemented parameter of RtpParameters.");

}

RtpParameters parameters;

parameters.encodings = init.send_encodings;

// Encodings are dropped from the tail if too many are provided.

size_t max_simulcast_streams =

media_type == cricket::MEDIA_TYPE_VIDEO ? kMaxSimulcastStreams : 1u;

if (parameters.encodings.size() > max_simulcast_streams) {

parameters.encodings.erase(

parameters.encodings.begin() + max_simulcast_streams,

parameters.encodings.end());

}

// Single RID should be removed.

if (parameters.encodings.size() == 1 &&

!parameters.encodings[0].rid.empty()) {

RTC_LOG(LS_INFO) << "Removing RID: " << parameters.encodings[0].rid << ".";

parameters.encodings[0].rid.clear();

}

// If RIDs were not provided, they are generated for simulcast scenario.

if (parameters.encodings.size() > 1 && num_rids == 0) {

rtc::UniqueStringGenerator rid_generator;

for (RtpEncodingParameters& encoding : parameters.encodings) {

encoding.rid = rid_generator();

}

}

if (UnimplementedRtpParameterHasValue(parameters)) {

LOG_AND_RETURN_ERROR(

RTCErrorType::UNSUPPORTED_PARAMETER,

"Attempted to set an unimplemented parameter of RtpParameters.");

}

auto result = cricket::CheckRtpParametersValues(parameters);

if (!result.ok()) {

LOG_AND_RETURN_ERROR(result.type(), result.message());

}

RTC_LOG(LS_INFO) << "Adding " << cricket::MediaTypeToString(media_type)

<< " transceiver in response to a call to AddTransceiver.";

// Set the sender ID equal to the track ID if the track is specified unless

// that sender ID is already in use.

// Add by Ivan to new frame encryptor interface

rtc::scoped_refptr<FrameEncryptorInterface> fake_frame_encryptor(

new FakeFrameEncryptor());

std::string sender_id = (track && !rtp_manager()->FindSenderById(track->id())

? track->id()

: rtc::CreateRandomUuid());

auto sender = rtp_manager()->CreateSender(

media_type, sender_id, track, init.stream_ids, parameters.encodings);

// Add by Ivan: add a fake frame encryptor to the sender.

sender->SetFrameEncryptor(fake_frame_encryptor);

auto receiver =

rtp_manager()->CreateReceiver(media_type, rtc::CreateRandomUuid());

auto transceiver = rtp_manager()->CreateAndAddTransceiver(sender, receiver);

transceiver->internal()->set_direction(init.direction);

if (update_negotiation_needed) {

sdp_handler_->UpdateNegotiationNeeded();

}

return rtc::scoped_refptr<RtpTransceiverInterface>(transceiver);

}

I already put

#include "api/test/fake_frame_decryptor.h"

#include "api/test/fake_frame_encryptor.h"

and

#include "api/crypto/frame_decryptor_interface.h"

#include "api/crypto/frame_encryptor_interface.h"

Actually, I am new to C++ so I am not really familiar with it, Maybe anyone who already implements a custom frame encryptor in webrtc android could give me some clue or help.

Really appreciate any help

Best Regards,

Ivan

[Ivan Hutomo]

Hello everyone just wants to follow up on this question again. How is the correct way to use this frame encryptor in Android, does my approach still wrong? Do I need to implement this in Java directly? Thanks in advance