blob: 28e8ef86b23fac2f9466813ccbe935fb6cc7a722 [file] [log] [blame]
/*
* Copyright (c) 2016 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/rtp_frame_reference_finder.h"
#include <algorithm>
#include <limits>
#include "absl/types/variant.h"
#include "modules/video_coding/frame_object.h"
#include "modules/video_coding/packet_buffer.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/system/fallthrough.h"
namespace webrtc {
namespace video_coding {
RtpFrameReferenceFinder::RtpFrameReferenceFinder(
OnCompleteFrameCallback* frame_callback)
: last_picture_id_(-1),
last_unwrap_(-1),
current_ss_idx_(0),
cleared_to_seq_num_(-1),
frame_callback_(frame_callback) {}
void RtpFrameReferenceFinder::ManageFrame(
std::unique_ptr<RtpFrameObject> frame) {
rtc::CritScope lock(&crit_);
// If we have cleared past this frame, drop it.
if (cleared_to_seq_num_ != -1 &&
AheadOf<uint16_t>(cleared_to_seq_num_, frame->first_seq_num())) {
return;
}
FrameDecision decision = ManageFrameInternal(frame.get());
switch (decision) {
case kStash:
if (stashed_frames_.size() > kMaxStashedFrames)
stashed_frames_.pop_back();
stashed_frames_.push_front(std::move(frame));
break;
case kHandOff:
frame_callback_->OnCompleteFrame(std::move(frame));
RetryStashedFrames();
break;
case kDrop:
break;
}
}
void RtpFrameReferenceFinder::RetryStashedFrames() {
bool complete_frame = false;
do {
complete_frame = false;
for (auto frame_it = stashed_frames_.begin();
frame_it != stashed_frames_.end();) {
FrameDecision decision = ManageFrameInternal(frame_it->get());
switch (decision) {
case kStash:
++frame_it;
break;
case kHandOff:
complete_frame = true;
frame_callback_->OnCompleteFrame(std::move(*frame_it));
RTC_FALLTHROUGH();
case kDrop:
frame_it = stashed_frames_.erase(frame_it);
}
}
} while (complete_frame);
}
RtpFrameReferenceFinder::FrameDecision
RtpFrameReferenceFinder::ManageFrameInternal(RtpFrameObject* frame) {
switch (frame->codec_type()) {
case kVideoCodecVP8:
return ManageFrameVp8(frame);
case kVideoCodecVP9:
return ManageFrameVp9(frame);
default:
return ManageFrameGeneric(frame, kNoPictureId);
}
}
void RtpFrameReferenceFinder::PaddingReceived(uint16_t seq_num) {
rtc::CritScope lock(&crit_);
auto clean_padding_to =
stashed_padding_.lower_bound(seq_num - kMaxPaddingAge);
stashed_padding_.erase(stashed_padding_.begin(), clean_padding_to);
stashed_padding_.insert(seq_num);
UpdateLastPictureIdWithPadding(seq_num);
RetryStashedFrames();
}
void RtpFrameReferenceFinder::ClearTo(uint16_t seq_num) {
rtc::CritScope lock(&crit_);
cleared_to_seq_num_ = seq_num;
auto it = stashed_frames_.begin();
while (it != stashed_frames_.end()) {
if (AheadOf<uint16_t>(cleared_to_seq_num_, (*it)->first_seq_num())) {
it = stashed_frames_.erase(it);
} else {
++it;
}
}
}
void RtpFrameReferenceFinder::UpdateLastPictureIdWithPadding(uint16_t seq_num) {
auto gop_seq_num_it = last_seq_num_gop_.upper_bound(seq_num);
// If this padding packet "belongs" to a group of pictures that we don't track
// anymore, do nothing.
if (gop_seq_num_it == last_seq_num_gop_.begin())
return;
--gop_seq_num_it;
// Calculate the next contiuous sequence number and search for it in
// the padding packets we have stashed.
uint16_t next_seq_num_with_padding = gop_seq_num_it->second.second + 1;
auto padding_seq_num_it =
stashed_padding_.lower_bound(next_seq_num_with_padding);
// While there still are padding packets and those padding packets are
// continuous, then advance the "last-picture-id-with-padding" and remove
// the stashed padding packet.
while (padding_seq_num_it != stashed_padding_.end() &&
*padding_seq_num_it == next_seq_num_with_padding) {
gop_seq_num_it->second.second = next_seq_num_with_padding;
++next_seq_num_with_padding;
padding_seq_num_it = stashed_padding_.erase(padding_seq_num_it);
}
// In the case where the stream has been continuous without any new keyframes
// for a while there is a risk that new frames will appear to be older than
// the keyframe they belong to due to wrapping sequence number. In order
// to prevent this we advance the picture id of the keyframe every so often.
if (ForwardDiff(gop_seq_num_it->first, seq_num) > 10000) {
RTC_DCHECK_EQ(1ul, last_seq_num_gop_.size());
last_seq_num_gop_[seq_num] = gop_seq_num_it->second;
last_seq_num_gop_.erase(gop_seq_num_it);
}
}
RtpFrameReferenceFinder::FrameDecision
RtpFrameReferenceFinder::ManageFrameGeneric(RtpFrameObject* frame,
int picture_id) {
// If |picture_id| is specified then we use that to set the frame references,
// otherwise we use sequence number.
if (picture_id != kNoPictureId) {
if (last_unwrap_ == -1)
last_unwrap_ = picture_id;
frame->id.picture_id = unwrapper_.Unwrap(picture_id);
frame->num_references = frame->frame_type() == kVideoFrameKey ? 0 : 1;
frame->references[0] = frame->id.picture_id - 1;
return kHandOff;
}
if (frame->frame_type() == kVideoFrameKey) {
last_seq_num_gop_.insert(std::make_pair(
frame->last_seq_num(),
std::make_pair(frame->last_seq_num(), frame->last_seq_num())));
}
// We have received a frame but not yet a keyframe, stash this frame.
if (last_seq_num_gop_.empty())
return kStash;
// Clean up info for old keyframes but make sure to keep info
// for the last keyframe.
auto clean_to = last_seq_num_gop_.lower_bound(frame->last_seq_num() - 100);
for (auto it = last_seq_num_gop_.begin();
it != clean_to && last_seq_num_gop_.size() > 1;) {
it = last_seq_num_gop_.erase(it);
}
// Find the last sequence number of the last frame for the keyframe
// that this frame indirectly references.
auto seq_num_it = last_seq_num_gop_.upper_bound(frame->last_seq_num());
if (seq_num_it == last_seq_num_gop_.begin()) {
RTC_LOG(LS_WARNING) << "Generic frame with packet range ["
<< frame->first_seq_num() << ", "
<< frame->last_seq_num()
<< "] has no GoP, dropping frame.";
return kDrop;
}
seq_num_it--;
// Make sure the packet sequence numbers are continuous, otherwise stash
// this frame.
uint16_t last_picture_id_gop = seq_num_it->second.first;
uint16_t last_picture_id_with_padding_gop = seq_num_it->second.second;
if (frame->frame_type() == kVideoFrameDelta) {
uint16_t prev_seq_num = frame->first_seq_num() - 1;
if (prev_seq_num != last_picture_id_with_padding_gop)
return kStash;
}
RTC_DCHECK(AheadOrAt(frame->last_seq_num(), seq_num_it->first));
// Since keyframes can cause reordering we can't simply assign the
// picture id according to some incrementing counter.
frame->id.picture_id = frame->last_seq_num();
frame->num_references = frame->frame_type() == kVideoFrameDelta;
frame->references[0] = generic_unwrapper_.Unwrap(last_picture_id_gop);
if (AheadOf<uint16_t>(frame->id.picture_id, last_picture_id_gop)) {
seq_num_it->second.first = frame->id.picture_id;
seq_num_it->second.second = frame->id.picture_id;
}
last_picture_id_ = frame->id.picture_id;
UpdateLastPictureIdWithPadding(frame->id.picture_id);
frame->id.picture_id = generic_unwrapper_.Unwrap(frame->id.picture_id);
return kHandOff;
}
RtpFrameReferenceFinder::FrameDecision RtpFrameReferenceFinder::ManageFrameVp8(
RtpFrameObject* frame) {
absl::optional<RTPVideoTypeHeader> rtp_codec_header = frame->GetCodecHeader();
if (!rtp_codec_header) {
RTC_LOG(LS_WARNING)
<< "Failed to get codec header from frame, dropping frame.";
return kDrop;
}
const RTPVideoHeaderVP8& codec_header =
absl::get<RTPVideoHeaderVP8>(*rtp_codec_header);
if (codec_header.pictureId == kNoPictureId ||
codec_header.temporalIdx == kNoTemporalIdx ||
codec_header.tl0PicIdx == kNoTl0PicIdx) {
return ManageFrameGeneric(std::move(frame), codec_header.pictureId);
}
frame->id.picture_id = codec_header.pictureId % kPicIdLength;
if (last_unwrap_ == -1)
last_unwrap_ = codec_header.pictureId;
if (last_picture_id_ == -1)
last_picture_id_ = frame->id.picture_id;
// Find if there has been a gap in fully received frames and save the picture
// id of those frames in |not_yet_received_frames_|.
if (AheadOf<uint16_t, kPicIdLength>(frame->id.picture_id, last_picture_id_)) {
do {
last_picture_id_ = Add<kPicIdLength>(last_picture_id_, 1);
not_yet_received_frames_.insert(last_picture_id_);
} while (last_picture_id_ != frame->id.picture_id);
}
int64_t unwrapped_tl0 = tl0_unwrapper_.Unwrap(codec_header.tl0PicIdx);
// Clean up info for base layers that are too old.
int64_t old_tl0_pic_idx = unwrapped_tl0 - kMaxLayerInfo;
auto clean_layer_info_to = layer_info_.lower_bound(old_tl0_pic_idx);
layer_info_.erase(layer_info_.begin(), clean_layer_info_to);
// Clean up info about not yet received frames that are too old.
uint16_t old_picture_id =
Subtract<kPicIdLength>(frame->id.picture_id, kMaxNotYetReceivedFrames);
auto clean_frames_to = not_yet_received_frames_.lower_bound(old_picture_id);
not_yet_received_frames_.erase(not_yet_received_frames_.begin(),
clean_frames_to);
if (frame->frame_type() == kVideoFrameKey) {
frame->num_references = 0;
layer_info_[unwrapped_tl0].fill(-1);
UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
return kHandOff;
}
auto layer_info_it = layer_info_.find(
codec_header.temporalIdx == 0 ? unwrapped_tl0 - 1 : unwrapped_tl0);
// If we don't have the base layer frame yet, stash this frame.
if (layer_info_it == layer_info_.end())
return kStash;
// A non keyframe base layer frame has been received, copy the layer info
// from the previous base layer frame and set a reference to the previous
// base layer frame.
if (codec_header.temporalIdx == 0) {
layer_info_it =
layer_info_.emplace(unwrapped_tl0, layer_info_it->second).first;
frame->num_references = 1;
frame->references[0] = layer_info_it->second[0];
UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
return kHandOff;
}
// Layer sync frame, this frame only references its base layer frame.
if (codec_header.layerSync) {
frame->num_references = 1;
frame->references[0] = layer_info_it->second[0];
UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
return kHandOff;
}
// Find all references for this frame.
frame->num_references = 0;
for (uint8_t layer = 0; layer <= codec_header.temporalIdx; ++layer) {
// If we have not yet received a previous frame on this temporal layer,
// stash this frame.
if (layer_info_it->second[layer] == -1)
return kStash;
// If the last frame on this layer is ahead of this frame it means that
// a layer sync frame has been received after this frame for the same
// base layer frame, drop this frame.
if (AheadOf<uint16_t, kPicIdLength>(layer_info_it->second[layer],
frame->id.picture_id)) {
return kDrop;
}
// If we have not yet received a frame between this frame and the referenced
// frame then we have to wait for that frame to be completed first.
auto not_received_frame_it =
not_yet_received_frames_.upper_bound(layer_info_it->second[layer]);
if (not_received_frame_it != not_yet_received_frames_.end() &&
AheadOf<uint16_t, kPicIdLength>(frame->id.picture_id,
*not_received_frame_it)) {
return kStash;
}
if (!(AheadOf<uint16_t, kPicIdLength>(frame->id.picture_id,
layer_info_it->second[layer]))) {
RTC_LOG(LS_WARNING) << "Frame with picture id " << frame->id.picture_id
<< " and packet range [" << frame->first_seq_num()
<< ", " << frame->last_seq_num()
<< "] already received, "
<< " dropping frame.";
return kDrop;
}
++frame->num_references;
frame->references[layer] = layer_info_it->second[layer];
}
UpdateLayerInfoVp8(frame, unwrapped_tl0, codec_header.temporalIdx);
return kHandOff;
}
void RtpFrameReferenceFinder::UpdateLayerInfoVp8(RtpFrameObject* frame,
int64_t unwrapped_tl0,
uint8_t temporal_idx) {
auto layer_info_it = layer_info_.find(unwrapped_tl0);
// Update this layer info and newer.
while (layer_info_it != layer_info_.end()) {
if (layer_info_it->second[temporal_idx] != -1 &&
AheadOf<uint16_t, kPicIdLength>(layer_info_it->second[temporal_idx],
frame->id.picture_id)) {
// The frame was not newer, then no subsequent layer info have to be
// update.
break;
}
layer_info_it->second[temporal_idx] = frame->id.picture_id;
++unwrapped_tl0;
layer_info_it = layer_info_.find(unwrapped_tl0);
}
not_yet_received_frames_.erase(frame->id.picture_id);
UnwrapPictureIds(frame);
}
RtpFrameReferenceFinder::FrameDecision RtpFrameReferenceFinder::ManageFrameVp9(
RtpFrameObject* frame) {
absl::optional<RTPVideoTypeHeader> rtp_codec_header = frame->GetCodecHeader();
if (!rtp_codec_header) {
RTC_LOG(LS_WARNING)
<< "Failed to get codec header from frame, dropping frame.";
return kDrop;
}
const RTPVideoHeaderVP9& codec_header =
absl::get<RTPVideoHeaderVP9>(*rtp_codec_header);
if (codec_header.picture_id == kNoPictureId ||
codec_header.temporal_idx == kNoTemporalIdx) {
return ManageFrameGeneric(std::move(frame), codec_header.picture_id);
}
frame->id.spatial_layer = codec_header.spatial_idx;
frame->inter_layer_predicted = codec_header.inter_layer_predicted;
frame->id.picture_id = codec_header.picture_id % kPicIdLength;
if (last_unwrap_ == -1)
last_unwrap_ = codec_header.picture_id;
if (last_picture_id_ == -1)
last_picture_id_ = frame->id.picture_id;
if (codec_header.flexible_mode) {
frame->num_references = codec_header.num_ref_pics;
for (size_t i = 0; i < frame->num_references; ++i) {
frame->references[i] = Subtract<kPicIdLength>(frame->id.picture_id,
codec_header.pid_diff[i]);
}
UnwrapPictureIds(frame);
return kHandOff;
}
if (codec_header.tl0_pic_idx == kNoTl0PicIdx) {
RTC_LOG(LS_WARNING) << "TL0PICIDX is expected to be present in "
"non-flexible mode.";
return kDrop;
}
GofInfo* info;
int64_t unwrapped_tl0 = tl0_unwrapper_.Unwrap(codec_header.tl0_pic_idx);
if (codec_header.ss_data_available) {
if (codec_header.temporal_idx != 0) {
RTC_LOG(LS_WARNING) << "Received scalability structure on a non base "
"layer frame. Scalability structure ignored.";
} else {
current_ss_idx_ = Add<kMaxGofSaved>(current_ss_idx_, 1);
if (codec_header.gof.num_frames_in_gof == 0 ||
codec_header.gof.num_frames_in_gof > kMaxVp9FramesInGof) {
return kDrop;
}
scalability_structures_[current_ss_idx_] = codec_header.gof;
scalability_structures_[current_ss_idx_].pid_start = frame->id.picture_id;
gof_info_.emplace(unwrapped_tl0,
GofInfo(&scalability_structures_[current_ss_idx_],
frame->id.picture_id));
}
const auto gof_info_it = gof_info_.find(unwrapped_tl0);
if (gof_info_it == gof_info_.end())
return kStash;
info = &gof_info_it->second;
if (frame->frame_type() == kVideoFrameKey) {
frame->num_references = 0;
FrameReceivedVp9(frame->id.picture_id, info);
UnwrapPictureIds(frame);
return kHandOff;
}
} else {
if (frame->frame_type() == kVideoFrameKey) {
RTC_LOG(LS_WARNING) << "Received keyframe without scalability structure";
return kDrop;
}
auto gof_info_it = gof_info_.find(
(codec_header.temporal_idx == 0) ? unwrapped_tl0 - 1 : unwrapped_tl0);
// Gof info for this frame is not available yet, stash this frame.
if (gof_info_it == gof_info_.end())
return kStash;
if (codec_header.temporal_idx == 0) {
gof_info_it = gof_info_
.emplace(unwrapped_tl0, GofInfo(gof_info_it->second.gof,
frame->id.picture_id))
.first;
}
info = &gof_info_it->second;
}
// Clean up info for base layers that are too old.
int64_t old_tl0_pic_idx = unwrapped_tl0 - kMaxGofSaved;
auto clean_gof_info_to = gof_info_.lower_bound(old_tl0_pic_idx);
gof_info_.erase(gof_info_.begin(), clean_gof_info_to);
FrameReceivedVp9(frame->id.picture_id, info);
// Make sure we don't miss any frame that could potentially have the
// up switch flag set.
if (MissingRequiredFrameVp9(frame->id.picture_id, *info))
return kStash;
if (codec_header.temporal_up_switch)
up_switch_.emplace(frame->id.picture_id, codec_header.temporal_idx);
// Clean out old info about up switch frames.
uint16_t old_picture_id = Subtract<kPicIdLength>(frame->id.picture_id, 50);
auto up_switch_erase_to = up_switch_.lower_bound(old_picture_id);
up_switch_.erase(up_switch_.begin(), up_switch_erase_to);
size_t diff = ForwardDiff<uint16_t, kPicIdLength>(info->gof->pid_start,
frame->id.picture_id);
size_t gof_idx = diff % info->gof->num_frames_in_gof;
// Populate references according to the scalability structure.
frame->num_references = info->gof->num_ref_pics[gof_idx];
for (size_t i = 0; i < frame->num_references; ++i) {
frame->references[i] = Subtract<kPicIdLength>(
frame->id.picture_id, info->gof->pid_diff[gof_idx][i]);
// If this is a reference to a frame earlier than the last up switch point,
// then ignore this reference.
if (UpSwitchInIntervalVp9(frame->id.picture_id, codec_header.temporal_idx,
frame->references[i])) {
--frame->num_references;
}
}
UnwrapPictureIds(frame);
return kHandOff;
}
bool RtpFrameReferenceFinder::MissingRequiredFrameVp9(uint16_t picture_id,
const GofInfo& info) {
size_t diff =
ForwardDiff<uint16_t, kPicIdLength>(info.gof->pid_start, picture_id);
size_t gof_idx = diff % info.gof->num_frames_in_gof;
size_t temporal_idx = info.gof->temporal_idx[gof_idx];
if (temporal_idx >= kMaxTemporalLayers) {
RTC_LOG(LS_WARNING) << "At most " << kMaxTemporalLayers << " temporal "
<< "layers are supported.";
return true;
}
// For every reference this frame has, check if there is a frame missing in
// the interval (|ref_pid|, |picture_id|) in any of the lower temporal
// layers. If so, we are missing a required frame.
uint8_t num_references = info.gof->num_ref_pics[gof_idx];
for (size_t i = 0; i < num_references; ++i) {
uint16_t ref_pid =
Subtract<kPicIdLength>(picture_id, info.gof->pid_diff[gof_idx][i]);
for (size_t l = 0; l < temporal_idx; ++l) {
auto missing_frame_it = missing_frames_for_layer_[l].lower_bound(ref_pid);
if (missing_frame_it != missing_frames_for_layer_[l].end() &&
AheadOf<uint16_t, kPicIdLength>(picture_id, *missing_frame_it)) {
return true;
}
}
}
return false;
}
void RtpFrameReferenceFinder::FrameReceivedVp9(uint16_t picture_id,
GofInfo* info) {
int last_picture_id = info->last_picture_id;
size_t gof_size = std::min(info->gof->num_frames_in_gof, kMaxVp9FramesInGof);
// If there is a gap, find which temporal layer the missing frames
// belong to and add the frame as missing for that temporal layer.
// Otherwise, remove this frame from the set of missing frames.
if (AheadOf<uint16_t, kPicIdLength>(picture_id, last_picture_id)) {
size_t diff = ForwardDiff<uint16_t, kPicIdLength>(info->gof->pid_start,
last_picture_id);
size_t gof_idx = diff % gof_size;
last_picture_id = Add<kPicIdLength>(last_picture_id, 1);
while (last_picture_id != picture_id) {
gof_idx = (gof_idx + 1) % gof_size;
RTC_CHECK(gof_idx < kMaxVp9FramesInGof);
size_t temporal_idx = info->gof->temporal_idx[gof_idx];
if (temporal_idx >= kMaxTemporalLayers) {
RTC_LOG(LS_WARNING) << "At most " << kMaxTemporalLayers << " temporal "
<< "layers are supported.";
return;
}
missing_frames_for_layer_[temporal_idx].insert(last_picture_id);
last_picture_id = Add<kPicIdLength>(last_picture_id, 1);
}
info->last_picture_id = last_picture_id;
} else {
size_t diff =
ForwardDiff<uint16_t, kPicIdLength>(info->gof->pid_start, picture_id);
size_t gof_idx = diff % gof_size;
RTC_CHECK(gof_idx < kMaxVp9FramesInGof);
size_t temporal_idx = info->gof->temporal_idx[gof_idx];
if (temporal_idx >= kMaxTemporalLayers) {
RTC_LOG(LS_WARNING) << "At most " << kMaxTemporalLayers << " temporal "
<< "layers are supported.";
return;
}
missing_frames_for_layer_[temporal_idx].erase(picture_id);
}
}
bool RtpFrameReferenceFinder::UpSwitchInIntervalVp9(uint16_t picture_id,
uint8_t temporal_idx,
uint16_t pid_ref) {
for (auto up_switch_it = up_switch_.upper_bound(pid_ref);
up_switch_it != up_switch_.end() &&
AheadOf<uint16_t, kPicIdLength>(picture_id, up_switch_it->first);
++up_switch_it) {
if (up_switch_it->second < temporal_idx)
return true;
}
return false;
}
void RtpFrameReferenceFinder::UnwrapPictureIds(RtpFrameObject* frame) {
for (size_t i = 0; i < frame->num_references; ++i)
frame->references[i] = unwrapper_.Unwrap(frame->references[i]);
frame->id.picture_id = unwrapper_.Unwrap(frame->id.picture_id);
}
} // namespace video_coding
} // namespace webrtc