uint32_t
MediaEngineCameraVideoSource::GetBestFitnessDistance(
const nsTArray<const MediaTrackConstraintSet*>& aConstraintSets)
{
size_t num = NumCapabilities();
CapabilitySet candidateSet;
for (size_t i = 0; i < num; i++) {
candidateSet.AppendElement(i);
}
bool first = true;
for (const MediaTrackConstraintSet* cs : aConstraintSets) {
for (size_t i = 0; i < candidateSet.Length(); ) {
auto& candidate = candidateSet[i];
webrtc::CaptureCapability cap;
GetCapability(candidate.mIndex, cap);
uint32_t distance = GetFitnessDistance(cap, *cs, !first);
if (distance == UINT32_MAX) {
candidateSet.RemoveElementAt(i);
} else {
++i;
if (first) {
candidate.mDistance = distance;
}
}
}
first = false;
}
if (!candidateSet.Length()) {
return UINT32_MAX;
}
TrimLessFitCandidates(candidateSet);
return candidateSet[0].mDistance;
}
/* static */ void
MediaEngineCameraVideoSource::TrimLessFitCandidates(CapabilitySet& set) {
uint32_t best = UINT32_MAX;
for (auto& candidate : set) {
if (best > candidate.mDistance) {
best = candidate.mDistance;
}
}
for (size_t i = 0; i < set.Length();) {
if (set[i].mDistance > best) {
set.RemoveElementAt(i);
} else {
++i;
}
}
MOZ_ASSERT(set.Length());
}
bool
MediaEngineCameraVideoSource::ChooseCapability(
const MediaTrackConstraints &aConstraints,
const MediaEnginePrefs &aPrefs,
const nsString& aDeviceId)
{
if (MOZ_LOG_TEST(GetMediaManagerLog(), LogLevel::Debug)) {
LOG(("ChooseCapability: prefs: %dx%d @%d-%dfps",
aPrefs.GetWidth(), aPrefs.GetHeight(),
aPrefs.mFPS, aPrefs.mMinFPS));
LogConstraints(aConstraints, false);
if (aConstraints.mAdvanced.WasPassed()) {
LOG(("Advanced array[%u]:", aConstraints.mAdvanced.Value().Length()));
for (auto& advanced : aConstraints.mAdvanced.Value()) {
LogConstraints(advanced, true);
}
}
}
size_t num = NumCapabilities();
CapabilitySet candidateSet;
for (size_t i = 0; i < num; i++) {
candidateSet.AppendElement(i);
}
// First, filter capabilities by required constraints (min, max, exact).
for (size_t i = 0; i < candidateSet.Length();) {
auto& candidate = candidateSet[i];
webrtc::CaptureCapability cap;
GetCapability(candidate.mIndex, cap);
candidate.mDistance = GetFitnessDistance(cap, aConstraints, false, aDeviceId);
LogCapability("Capability", cap, candidate.mDistance);
if (candidate.mDistance == UINT32_MAX) {
candidateSet.RemoveElementAt(i);
} else {
++i;
}
}
// Filter further with all advanced constraints (that don't overconstrain).
if (aConstraints.mAdvanced.WasPassed()) {
for (const MediaTrackConstraintSet &cs : aConstraints.mAdvanced.Value()) {
CapabilitySet rejects;
for (size_t i = 0; i < candidateSet.Length();) {
auto& candidate = candidateSet[i];
webrtc::CaptureCapability cap;
GetCapability(candidate.mIndex, cap);
if (GetFitnessDistance(cap, cs, true, aDeviceId) == UINT32_MAX) {
rejects.AppendElement(candidate);
candidateSet.RemoveElementAt(i);
} else {
++i;
}
}
if (!candidateSet.Length()) {
candidateSet.AppendElements(Move(rejects));
}
}
}
if (!candidateSet.Length()) {
LOG(("failed to find capability match from %d choices",num));
return false;
}
// Remaining algorithm is up to the UA.
TrimLessFitCandidates(candidateSet);
// Any remaining multiples all have the same distance. A common case of this
// occurs when no ideal is specified. Lean toward defaults.
uint32_t sameDistance = candidateSet[0].mDistance;
{
MediaTrackConstraintSet prefs;
prefs.mWidth.SetAsLong() = aPrefs.GetWidth();
prefs.mHeight.SetAsLong() = aPrefs.GetHeight();
prefs.mFrameRate.SetAsDouble() = aPrefs.mFPS;
for (auto& candidate : candidateSet) {
webrtc::CaptureCapability cap;
GetCapability(candidate.mIndex, cap);
candidate.mDistance = GetFitnessDistance(cap, prefs, false, aDeviceId);
}
TrimLessFitCandidates(candidateSet);
}
// Any remaining multiples all have the same distance, but may vary on
// format. Some formats are more desirable for certain use like WebRTC.
// E.g. I420 over RGB24 can remove a needless format conversion.
bool found = false;
for (auto& candidate : candidateSet) {
webrtc::CaptureCapability cap;
GetCapability(candidate.mIndex, cap);
if (cap.rawType == webrtc::RawVideoType::kVideoI420 ||
cap.rawType == webrtc::RawVideoType::kVideoYUY2 ||
cap.rawType == webrtc::RawVideoType::kVideoYV12) {
mCapability = cap;
found = true;
break;
}
}
if (!found) {
GetCapability(candidateSet[0].mIndex, mCapability);
}
LogCapability("Chosen capability", mCapability, sameDistance);
return true;
}