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videolayerselector.go
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/
videolayerselector.go
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package sfu
import (
"fmt"
"sort"
"github.com/abdulhaseeb08/livekit-server/pkg/sfu/buffer"
dd "github.com/abdulhaseeb08/livekit-server/pkg/sfu/dependencydescriptor"
"github.com/abdulhaseeb08/protocol/logger"
)
type targetLayer struct {
Target int
Layer VideoLayers
}
type DDVideoLayerSelector struct {
logger logger.Logger
// TODO : fields for frame chain detect
// frameNumberWrapper Uint16Wrapper
// expectKeyFrame bool
decodeTargetLayer []targetLayer
layer VideoLayers
activeDecodeTargetsBitmask *uint32
structure *dd.FrameDependencyStructure
}
func NewDDVideoLayerSelector(logger logger.Logger) *DDVideoLayerSelector {
return &DDVideoLayerSelector{
logger: logger,
layer: VideoLayers{Spatial: 2, Temporal: 2},
}
}
func (s *DDVideoLayerSelector) Select(expPkt *buffer.ExtPacket, tp *TranslationParams) (selected bool) {
tp.marker = expPkt.Packet.Marker
if expPkt.DependencyDescriptor == nil {
// packet don't have dependency descriptor, pass check
return true
}
if expPkt.DependencyDescriptor.AttachedStructure != nil {
// update decode target layer and active decode targets
// TODO : these targets info can be shared by all the downtracks, no need calculate in every selector
s.updateDependencyStructure(expPkt.DependencyDescriptor.AttachedStructure)
}
// forward all packets before locking
if s.layer == InvalidLayers {
return true
}
// TODO : we don't have a rtp queue to ensure the order of packets now,
// so we don't know packet is lost/out of order, that cause us can't detect
// frame integrity, entire frame is forwareded, whether frame chain is broken.
// So use a simple check here, assume all the reference frame is forwarded and
// only check DTI of the active decode target.
// it is not effeciency, at last we need check frame chain integrity.
activeDecodeTargets := expPkt.DependencyDescriptor.ActiveDecodeTargetsBitmask
if activeDecodeTargets != nil {
s.logger.Debugw("active decode targets", "activeDecodeTargets", *activeDecodeTargets)
}
currentTarget := -1
for _, dt := range s.decodeTargetLayer {
// find target match with selected layer
if dt.Layer.Spatial <= s.layer.Spatial && dt.Layer.Temporal <= s.layer.Temporal {
if activeDecodeTargets == nil || ((*activeDecodeTargets)&(1<<dt.Target) != 0) {
// TODO : check frame chain integrity
currentTarget = dt.Target
// s.logger.Debugw("select target", "target", currentTarget, "layer", dt.layer, "dtis", expPkt.DependencyDescriptor.FrameDependencies.DecodeTargetIndications)
break
}
}
}
if currentTarget < 0 {
// s.logger.Debugw(fmt.Sprintf("drop packet for no target found, deocdeTargets %v, selected layer %v, s:%d, t:%d",
// s.decodeTargetLayer, s.layer, expPkt.DependencyDescriptor.FrameDependencies.SpatialId, expPkt.DependencyDescriptor.FrameDependencies.TemporalId))
// no active decode target, forward all packets
return false
}
dtis := expPkt.DependencyDescriptor.FrameDependencies.DecodeTargetIndications
if len(dtis) < currentTarget {
// dtis error, dependency descriptor might lost
s.logger.Debugw(fmt.Sprintf("drop packet for dtis error, dtis %v, currentTarget %d, s:%d, t:%d", dtis, currentTarget,
expPkt.DependencyDescriptor.FrameDependencies.SpatialId, expPkt.DependencyDescriptor.FrameDependencies.TemporalId))
return false
}
// TODO : if bandwidth in congest, could drop the 'Discardable' packet
if dti := dtis[currentTarget]; dti == dd.DecodeTargetNotPresent {
// s.logger.Debugw(fmt.Sprintf("drop packet for decode target not present, dtis %v, currentTarget %d, s:%d, t:%d", dtis, currentTarget,
// expPkt.DependencyDescriptor.FrameDependencies.SpatialId, expPkt.DependencyDescriptor.FrameDependencies.TemporalId))
return false
} else if dti == dd.DecodeTargetSwitch {
tp.switchingToTargetLayer = true
}
// TODO : add frame to forwarded queue if entire frame is forwarded
// s.logger.Debugw("select packet", "target", currentTarget, "layer", s.layer)
tp.ddExtension = &dd.DependencyDescriptorExtension{
Descriptor: expPkt.DependencyDescriptor,
Structure: s.structure,
}
if expPkt.DependencyDescriptor.AttachedStructure == nil && s.activeDecodeTargetsBitmask != nil {
// clone and override activebitmask
ddClone := *tp.ddExtension.Descriptor
ddClone.ActiveDecodeTargetsBitmask = s.activeDecodeTargetsBitmask
tp.ddExtension.Descriptor = &ddClone
// s.logger.Debugw("set active decode targets bitmask", "activeDecodeTargetsBitmask", s.activeDecodeTargetsBitmask)
}
mark := expPkt.Packet.Header.Marker || (expPkt.DependencyDescriptor.LastPacketInFrame && s.layer.Spatial == int32(expPkt.DependencyDescriptor.FrameDependencies.SpatialId))
tp.marker = mark
return true
}
func (s *DDVideoLayerSelector) SelectLayer(layer VideoLayers) {
// layer = VideoLayers{1, 1}
s.layer = layer
activeBitMask := uint32(0)
var maxSpatial, maxTemporal int32
for _, dt := range s.decodeTargetLayer {
if dt.Layer.Spatial > maxSpatial {
maxSpatial = dt.Layer.Spatial
}
if dt.Layer.Temporal > maxTemporal {
maxTemporal = dt.Layer.Temporal
}
if dt.Layer.Spatial <= layer.Spatial && dt.Layer.Temporal <= layer.Temporal {
activeBitMask |= 1 << dt.Target
}
}
if layer.Spatial == maxSpatial && layer.Temporal == maxTemporal {
// all the decode targets are selected
s.activeDecodeTargetsBitmask = nil
} else {
s.activeDecodeTargetsBitmask = &activeBitMask
}
s.logger.Debugw("select layer ", "layer", layer, "activeDecodeTargetsBitmask", s.activeDecodeTargetsBitmask)
}
func (s *DDVideoLayerSelector) updateDependencyStructure(structure *dd.FrameDependencyStructure) {
s.structure = structure
s.decodeTargetLayer = s.decodeTargetLayer[:0]
for target := 0; target < structure.NumDecodeTargets; target++ {
layer := VideoLayers{Spatial: 0, Temporal: 0}
for _, t := range structure.Templates {
if t.DecodeTargetIndications[target] != dd.DecodeTargetNotPresent {
if layer.Spatial < int32(t.SpatialId) {
layer.Spatial = int32(t.SpatialId)
}
if layer.Temporal < int32(t.TemporalId) {
layer.Temporal = int32(t.TemporalId)
}
}
}
s.decodeTargetLayer = append(s.decodeTargetLayer, targetLayer{target, layer})
}
// sort decode target layer by spatial and temporal from high to low
sort.Slice(s.decodeTargetLayer, func(i, j int) bool {
if s.decodeTargetLayer[i].Layer.Spatial == s.decodeTargetLayer[j].Layer.Spatial {
return s.decodeTargetLayer[i].Layer.Temporal > s.decodeTargetLayer[j].Layer.Temporal
}
return s.decodeTargetLayer[i].Layer.Spatial > s.decodeTargetLayer[j].Layer.Spatial
})
s.logger.Debugw(fmt.Sprintf("update decode targets: %v", s.decodeTargetLayer))
}
// TODO : use generic wrapper when updated to go 1.18
type Uint16Wrapper struct {
last_value *uint16
lastUnwrapped int32
}
func (w *Uint16Wrapper) Unwrap(value uint16) int32 {
if w.last_value == nil {
w.last_value = &value
w.lastUnwrapped = int32(value)
return int32(*w.last_value)
}
diff := value - *w.last_value
w.lastUnwrapped += int32(diff)
if diff == 0x8000 && value < *w.last_value {
w.lastUnwrapped -= 0x10000
} else if diff > 0x8000 {
w.lastUnwrapped -= 0x10000
}
*w.last_value = value
return w.lastUnwrapped
}