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/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/video_coding/main/source/session_info.h"
#include "modules/video_coding/main/source/packet.h"
namespace webrtc {
VCMSessionInfo::VCMSessionInfo()
: session_nack_(false),
complete_(false),
decodable_(false),
frame_type_(kVideoFrameDelta),
previous_frame_loss_(false),
packets_(),
empty_seq_num_low_(-1),
empty_seq_num_high_(-1),
packets_not_decodable_(0) {
}
void VCMSessionInfo::UpdateDataPointers(const uint8_t* old_base_ptr,
const uint8_t* new_base_ptr) {
for (PacketIterator it = packets_.begin(); it != packets_.end(); ++it)
if ((*it).dataPtr != NULL) {
assert(old_base_ptr != NULL && new_base_ptr != NULL);
(*it).dataPtr = new_base_ptr + ((*it).dataPtr - old_base_ptr);
}
}
int VCMSessionInfo::LowSequenceNumber() const {
if (packets_.empty())
return empty_seq_num_low_;
return packets_.front().seqNum;
}
int VCMSessionInfo::HighSequenceNumber() const {
if (packets_.empty())
return empty_seq_num_high_;
return LatestSequenceNumber(packets_.back().seqNum, empty_seq_num_high_,
NULL);
}
int VCMSessionInfo::PictureId() const {
if (packets_.empty() ||
packets_.front().codecSpecificHeader.codec != kRTPVideoVP8)
return kNoPictureId;
return packets_.front().codecSpecificHeader.codecHeader.VP8.pictureId;
}
int VCMSessionInfo::TemporalId() const {
if (packets_.empty() ||
packets_.front().codecSpecificHeader.codec != kRTPVideoVP8)
return kNoTemporalIdx;
return packets_.front().codecSpecificHeader.codecHeader.VP8.temporalIdx;
}
bool VCMSessionInfo::LayerSync() const {
if (packets_.empty() ||
packets_.front().codecSpecificHeader.codec != kRTPVideoVP8)
return false;
return packets_.front().codecSpecificHeader.codecHeader.VP8.layerSync;
}
int VCMSessionInfo::Tl0PicId() const {
if (packets_.empty() ||
packets_.front().codecSpecificHeader.codec != kRTPVideoVP8)
return kNoTl0PicIdx;
return packets_.front().codecSpecificHeader.codecHeader.VP8.tl0PicIdx;
}
bool VCMSessionInfo::NonReference() const {
if (packets_.empty() ||
packets_.front().codecSpecificHeader.codec != kRTPVideoVP8)
return false;
return packets_.front().codecSpecificHeader.codecHeader.VP8.nonReference;
}
void VCMSessionInfo::Reset() {
session_nack_ = false;
complete_ = false;
decodable_ = false;
frame_type_ = kVideoFrameDelta;
previous_frame_loss_ = false;
packets_.clear();
empty_seq_num_low_ = -1;
empty_seq_num_high_ = -1;
packets_not_decodable_ = 0;
}
int VCMSessionInfo::SessionLength() const {
int length = 0;
for (PacketIteratorConst it = packets_.begin(); it != packets_.end(); ++it)
length += (*it).sizeBytes;
return length;
}
int VCMSessionInfo::InsertBuffer(uint8_t* frame_buffer,
PacketIterator packet_it) {
VCMPacket& packet = *packet_it;
PacketIterator it;
int packet_size = packet.sizeBytes;
packet_size += (packet.insertStartCode ? kH264StartCodeLengthBytes : 0);
// Calculate the offset into the frame buffer for this packet.
int offset = 0;
for (it = packets_.begin(); it != packet_it; ++it)
offset += (*it).sizeBytes;
// Set the data pointer to pointing to the start of this packet in the
// frame buffer.
const uint8_t* data = packet.dataPtr;
packet.dataPtr = frame_buffer + offset;
packet.sizeBytes = packet_size;
ShiftSubsequentPackets(packet_it, packet_size);
const unsigned char startCode[] = {0, 0, 0, 1};
if (packet.insertStartCode) {
memcpy(const_cast<uint8_t*>(packet.dataPtr), startCode,
kH264StartCodeLengthBytes);
}
memcpy(const_cast<uint8_t*>(packet.dataPtr
+ (packet.insertStartCode ? kH264StartCodeLengthBytes : 0)),
data,
packet.sizeBytes);
return packet_size;
}
void VCMSessionInfo::ShiftSubsequentPackets(PacketIterator it,
int steps_to_shift) {
++it;
if (it == packets_.end())
return;
uint8_t* first_packet_ptr = const_cast<WebRtc_UWord8*>((*it).dataPtr);
int shift_length = 0;
// Calculate the total move length and move the data pointers in advance.
for (; it != packets_.end(); ++it) {
shift_length += (*it).sizeBytes;
if ((*it).dataPtr != NULL)
(*it).dataPtr += steps_to_shift;
}
memmove(first_packet_ptr + steps_to_shift, first_packet_ptr, shift_length);
}
void VCMSessionInfo::UpdateCompleteSession() {
if (packets_.front().isFirstPacket && packets_.back().markerBit) {
// Do we have all the packets in this session?
bool complete_session = true;
PacketIterator it = packets_.begin();
PacketIterator prev_it = it;
++it;
for (; it != packets_.end(); ++it) {
if (!InSequence(it, prev_it)) {
complete_session = false;
break;
}
prev_it = it;
}
complete_ = complete_session;
}
}
void VCMSessionInfo::UpdateDecodableSession(int rttMs) {
// Irrelevant if session is already complete or decodable
if (complete_ || decodable_)
return;
// First iteration - do nothing
}
bool VCMSessionInfo::complete() const {
return complete_;
}
bool VCMSessionInfo::decodable() const {
return decodable_;
}
// Find the end of the NAL unit which the packet pointed to by |packet_it|
// belongs to. Returns an iterator to the last packet of the frame if the end
// of the NAL unit wasn't found.
VCMSessionInfo::PacketIterator VCMSessionInfo::FindNaluEnd(
PacketIterator packet_it) const {
if ((*packet_it).completeNALU == kNaluEnd ||
(*packet_it).completeNALU == kNaluComplete) {
return packet_it;
}
// Find the end of the NAL unit.
for (; packet_it != packets_.end(); ++packet_it) {
if (((*packet_it).completeNALU == kNaluComplete &&
(*packet_it).sizeBytes > 0) ||
// Found next NALU.
(*packet_it).completeNALU == kNaluStart)
return --packet_it;
if ((*packet_it).completeNALU == kNaluEnd)
return packet_it;
}
// The end wasn't found.
return --packet_it;
}
int VCMSessionInfo::DeletePacketData(PacketIterator start,
PacketIterator end) {
int bytes_to_delete = 0; // The number of bytes to delete.
PacketIterator packet_after_end = end;
++packet_after_end;
// Get the number of bytes to delete.
// Clear the size of these packets.
for (PacketIterator it = start; it != packet_after_end; ++it) {
bytes_to_delete += (*it).sizeBytes;
(*it).sizeBytes = 0;
(*it).dataPtr = NULL;
++packets_not_decodable_;
}
if (bytes_to_delete > 0)
ShiftSubsequentPackets(end, -bytes_to_delete);
return bytes_to_delete;
}
int VCMSessionInfo::BuildVP8FragmentationHeader(
uint8_t* frame_buffer,
int frame_buffer_length,
RTPFragmentationHeader* fragmentation) {
int new_length = 0;
// Allocate space for max number of partitions
fragmentation->VerifyAndAllocateFragmentationHeader(kMaxVP8Partitions);
fragmentation->fragmentationVectorSize = 0;
memset(fragmentation->fragmentationLength, 0,
kMaxVP8Partitions * sizeof(WebRtc_UWord32));
if (packets_.empty())
return new_length;
PacketIterator it = FindNextPartitionBeginning(packets_.begin(),
&packets_not_decodable_);
while (it != packets_.end()) {
const int partition_id =
(*it).codecSpecificHeader.codecHeader.VP8.partitionId;
PacketIterator partition_end = FindPartitionEnd(it);
fragmentation->fragmentationOffset[partition_id] =
(*it).dataPtr - frame_buffer;
assert(fragmentation->fragmentationOffset[partition_id] <
static_cast<WebRtc_UWord32>(frame_buffer_length));
fragmentation->fragmentationLength[partition_id] =
(*partition_end).dataPtr + (*partition_end).sizeBytes - (*it).dataPtr;
assert(fragmentation->fragmentationLength[partition_id] <=
static_cast<WebRtc_UWord32>(frame_buffer_length));
new_length += fragmentation->fragmentationLength[partition_id];
++partition_end;
it = FindNextPartitionBeginning(partition_end, &packets_not_decodable_);
if (partition_id + 1 > fragmentation->fragmentationVectorSize)
fragmentation->fragmentationVectorSize = partition_id + 1;
}
// Set all empty fragments to start where the previous fragment ends,
// and have zero length.
if (fragmentation->fragmentationLength[0] == 0)
fragmentation->fragmentationOffset[0] = 0;
for (int i = 1; i < fragmentation->fragmentationVectorSize; ++i) {
if (fragmentation->fragmentationLength[i] == 0)
fragmentation->fragmentationOffset[i] =
fragmentation->fragmentationOffset[i - 1] +
fragmentation->fragmentationLength[i - 1];
assert(i == 0 ||
fragmentation->fragmentationOffset[i] >=
fragmentation->fragmentationOffset[i - 1]);
}
assert(new_length <= frame_buffer_length);
return new_length;
}
VCMSessionInfo::PacketIterator VCMSessionInfo::FindNextPartitionBeginning(
PacketIterator it, int* packets_skipped) const {
while (it != packets_.end()) {
if ((*it).codecSpecificHeader.codecHeader.VP8.beginningOfPartition) {
return it;
} else if (packets_skipped != NULL) {
// This packet belongs to a partition with a previous loss and can't
// be decoded.
++(*packets_skipped);
}
++it;
}
return it;
}
VCMSessionInfo::PacketIterator VCMSessionInfo::FindPartitionEnd(
PacketIterator it) const {
assert((*it).codec == kVideoCodecVP8);
PacketIterator prev_it = it;
const int partition_id =
(*it).codecSpecificHeader.codecHeader.VP8.partitionId;
while (it != packets_.end()) {
bool beginning =
(*it).codecSpecificHeader.codecHeader.VP8.beginningOfPartition;
int current_partition_id =
(*it).codecSpecificHeader.codecHeader.VP8.partitionId;
bool packet_loss_found = (!beginning && !InSequence(it, prev_it));
if (packet_loss_found ||
(beginning && current_partition_id != partition_id)) {
// Missing packet, the previous packet was the last in sequence.
return prev_it;
}
prev_it = it;
++it;
}
return prev_it;
}
bool VCMSessionInfo::InSequence(const PacketIterator& packet_it,
const PacketIterator& prev_packet_it) {
// If the two iterators are pointing to the same packet they are considered
// to be in sequence.
return (packet_it == prev_packet_it ||
(static_cast<WebRtc_UWord16>((*prev_packet_it).seqNum + 1) ==
(*packet_it).seqNum));
}
int VCMSessionInfo::MakeDecodable() {
int return_length = 0;
PacketIterator it = packets_.begin();
// Make sure we remove the first NAL unit if it's not decodable.
if ((*it).completeNALU == kNaluIncomplete ||
(*it).completeNALU == kNaluEnd) {
PacketIterator nalu_end = FindNaluEnd(it);
return_length += DeletePacketData(it, nalu_end);
it = nalu_end;
}
PacketIterator prev_it = it;
// Take care of the rest of the NAL units.
for (; it != packets_.end(); ++it) {
bool start_of_nalu = ((*it).completeNALU == kNaluStart ||
(*it).completeNALU == kNaluComplete);
if (!start_of_nalu && !InSequence(it, prev_it)) {
// Found a sequence number gap due to packet loss.
PacketIterator nalu_end = FindNaluEnd(it);
return_length += DeletePacketData(it, nalu_end);
it = nalu_end;
}
prev_it = it;
}
return return_length;
}
int VCMSessionInfo::BuildHardNackList(int* seq_num_list,
int seq_num_list_length) {
if (NULL == seq_num_list || seq_num_list_length < 1) {
return -1;
}
if (packets_.empty()) {
return 0;
}
// Find end point (index of entry equals the sequence number of the first
// packet).
int index = 0;
for (; index < seq_num_list_length; ++index) {
if (seq_num_list[index] == packets_.front().seqNum) {
seq_num_list[index] = -1;
++index;
break;
}
}
// Zero out between the first entry and the end point.
PacketIterator it = packets_.begin();
PacketIterator prev_it = it;
++it;
while (it != packets_.end() && index < seq_num_list_length) {
if (!InSequence(it, prev_it)) {
// Found a sequence number gap due to packet loss.
index += PacketsMissing(it, prev_it);
session_nack_ = true;
}
seq_num_list[index] = -1;
++index;
prev_it = it;
++it;
}
if (!packets_.front().isFirstPacket)
session_nack_ = true;
return 0;
}
int VCMSessionInfo::BuildSoftNackList(int* seq_num_list,
int seq_num_list_length,
int rtt_ms) {
if (NULL == seq_num_list || seq_num_list_length < 1) {
return -1;
}
if (packets_.empty() && empty_seq_num_low_ == -1) {
return 0;
}
int index = 0;
int low_seq_num = (packets_.empty()) ? empty_seq_num_low_:
packets_.front().seqNum;
// Find entrance point (index of entry equals the sequence number of the
// first packet).
for (; index < seq_num_list_length; ++index) {
if (seq_num_list[index] == low_seq_num) {
seq_num_list[index] = -1;
break;
}
}
// TODO(mikhal): 1. Update score based on RTT value 2. Add partition data.
// Use the previous available.
bool base_available = false;
if ((index > 0) && (seq_num_list[index] == -1)) {
// Found first packet, for now let's go only one back.
if ((seq_num_list[index - 1] == -1) || (seq_num_list[index - 1] == -2)) {
// This is indeed the first packet, as previous packet was populated.
base_available = true;
}
}
bool allow_nack = (!packets_.front().isFirstPacket || !base_available);
// Zero out between first entry and end point.
int media_high_seq_num;
if (HaveLastPacket()) {
media_high_seq_num = packets_.back().seqNum;
} else {
// Estimation.
if (empty_seq_num_low_ >= 0) {
// Assuming empty packets have later sequence numbers than media packets.
media_high_seq_num = empty_seq_num_low_ - 1;
} else {
// Since this frame doesn't have the marker bit we can assume it should
// contain at least one more packet.
media_high_seq_num = static_cast<uint16_t>(packets_.back().seqNum + 1);
}
}
// Compute session/packet scores and thresholds:
// based on RTT and layer info (when available).
float nack_score_threshold = 0.25f;
float layer_score = TemporalId() > 0 ? 0.0f : 1.0f;
float rtt_score = 1.0f;
float score_multiplier = rtt_score * layer_score;
// Zero out between first entry and end point.
PacketIterator it = packets_.begin();
PacketIterator prev_it = it;
++index;
++it;
// TODO(holmer): Rewrite this in a way which better makes use of the list.
while (it != packets_.end() && index < seq_num_list_length) {
// Only process media packet sequence numbers.
if (LatestSequenceNumber((*it).seqNum, media_high_seq_num, NULL) ==
(*it).seqNum && (*it).seqNum != media_high_seq_num)
break;
if (!InSequence(it, prev_it)) {
// Found a sequence number gap due to packet loss.
int num_lost = PacketsMissing(it, prev_it);
for (int i = 0 ; i < num_lost; ++i) {
// Compute score of the packet.
float score = 1.0f;
// Multiply internal score (packet) by score multiplier.
score *= score_multiplier;
if (score > nack_score_threshold) {
allow_nack = true;
} else {
seq_num_list[index] = -1;
}
++index;
}
}
seq_num_list[index] = -1;
++index;
prev_it = it;
++it;
}
// Empty packets follow the data packets, and therefore have a higher
// sequence number. We do not want to NACK empty packets.
if ((empty_seq_num_low_ != -1) && (empty_seq_num_high_ != -1) &&
(index < seq_num_list_length)) {
// First make sure that we are at least at the minimum value (if not we are
// missing last packet(s)).
while (seq_num_list[index] < empty_seq_num_low_ &&
index < seq_num_list_length) {
++index;
}
// Mark empty packets.
while (seq_num_list[index] <= empty_seq_num_high_ &&
index < seq_num_list_length) {
seq_num_list[index] = -2;
++index;
}
}
session_nack_ = allow_nack;
return 0;
}
int VCMSessionInfo::PacketsMissing(const PacketIterator& packet_it,
const PacketIterator& prev_packet_it) {
if (packet_it == prev_packet_it)
return 0;
if ((*prev_packet_it).seqNum > (*packet_it).seqNum) // Wrap.
return static_cast<WebRtc_UWord16>(
static_cast<WebRtc_UWord32>((*packet_it).seqNum + 0x10000) -
(*prev_packet_it).seqNum) - 1;
else
return (*packet_it).seqNum - (*prev_packet_it).seqNum - 1;
}
bool
VCMSessionInfo::HaveLastPacket() const {
return (!packets_.empty() && packets_.back().markerBit);
}
bool
VCMSessionInfo::session_nack() const {
return session_nack_;
}
int VCMSessionInfo::InsertPacket(const VCMPacket& packet,
uint8_t* frame_buffer,
bool enable_decodable_state,
int rtt_ms) {
// Check if this is first packet (only valid for some codecs)
if (packet.isFirstPacket) {
// The first packet in a frame signals the frame type.
frame_type_ = packet.frameType;
} else if (frame_type_ == kFrameEmpty && packet.frameType != kFrameEmpty) {
// Update the frame type with the first media packet.
frame_type_ = packet.frameType;
}
if (packet.frameType == kFrameEmpty) {
// Update sequence number of an empty packet.
// Only media packets are inserted into the packet list.
InformOfEmptyPacket(packet.seqNum);
return 0;
}
if (packets_.size() == kMaxPacketsInSession)
return -1;
// Find the position of this packet in the packet list in sequence number
// order and insert it. Loop over the list in reverse order.
ReversePacketIterator rit = packets_.rbegin();
for (; rit != packets_.rend(); ++rit)
if (LatestSequenceNumber((*rit).seqNum, packet.seqNum, NULL) ==
packet.seqNum)
break;
// Check for duplicate packets.
if (rit != packets_.rend() &&
(*rit).seqNum == packet.seqNum && (*rit).sizeBytes > 0)
return -2;
// The insert operation invalidates the iterator |rit|.
PacketIterator packet_list_it = packets_.insert(rit.base(), packet);
int returnLength = InsertBuffer(frame_buffer, packet_list_it);
UpdateCompleteSession();
if (enable_decodable_state)
UpdateDecodableSession(rtt_ms);
return returnLength;
}
void VCMSessionInfo::InformOfEmptyPacket(uint16_t seq_num) {
// Empty packets may be FEC or filler packets. They are sequential and
// follow the data packets, therefore, we should only keep track of the high
// and low sequence numbers and may assume that the packets in between are
// empty packets belonging to the same frame (timestamp).
empty_seq_num_high_ = LatestSequenceNumber(seq_num, empty_seq_num_high_,
NULL);
if (empty_seq_num_low_ == -1 ||
LatestSequenceNumber(seq_num, empty_seq_num_low_, NULL) ==
empty_seq_num_low_)
empty_seq_num_low_ = seq_num;
}
int VCMSessionInfo::packets_not_decodable() const {
return packets_not_decodable_;
}
} // namespace webrtc