gecko-dev/dom/media/VideoUtils.cpp

714 lines
21 KiB
C++
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "VideoUtils.h"
#include "ImageContainer.h"
#include "MediaContainerType.h"
#include "MediaPrefs.h"
#include "MediaResource.h"
#include "TimeUnits.h"
#include "VorbisUtils.h"
#include "mozilla/Base64.h"
#include "mozilla/SharedThreadPool.h"
#include "mozilla/SystemGroup.h"
#include "mozilla/TaskCategory.h"
#include "mozilla/TaskQueue.h"
#include "mozilla/Telemetry.h"
#include "nsCharSeparatedTokenizer.h"
#include "nsContentTypeParser.h"
#include "nsIConsoleService.h"
#include "nsIRandomGenerator.h"
#include "nsIServiceManager.h"
#include "nsMathUtils.h"
#include "nsServiceManagerUtils.h"
#include "nsThreadUtils.h"
#include <functional>
#include <stdint.h>
namespace mozilla {
NS_NAMED_LITERAL_CSTRING(kEMEKeySystemClearkey, "org.w3.clearkey");
NS_NAMED_LITERAL_CSTRING(kEMEKeySystemWidevine, "com.widevine.alpha");
using layers::PlanarYCbCrImage;
using media::TimeUnit;
CheckedInt64 SaferMultDiv(int64_t aValue, uint32_t aMul, uint32_t aDiv) {
int64_t major = aValue / aDiv;
int64_t remainder = aValue % aDiv;
return CheckedInt64(remainder) * aMul / aDiv + CheckedInt64(major) * aMul;
}
// Converts from number of audio frames to microseconds, given the specified
// audio rate.
CheckedInt64 FramesToUsecs(int64_t aFrames, uint32_t aRate) {
return SaferMultDiv(aFrames, USECS_PER_S, aRate);
}
TimeUnit FramesToTimeUnit(int64_t aFrames, uint32_t aRate) {
int64_t major = aFrames / aRate;
int64_t remainder = aFrames % aRate;
return TimeUnit::FromMicroseconds(major) * USECS_PER_S +
(TimeUnit::FromMicroseconds(remainder) * USECS_PER_S) / aRate;
}
// Converts from microseconds to number of audio frames, given the specified
// audio rate.
CheckedInt64 UsecsToFrames(int64_t aUsecs, uint32_t aRate) {
return SaferMultDiv(aUsecs, aRate, USECS_PER_S);
}
// Format TimeUnit as number of frames at given rate.
CheckedInt64 TimeUnitToFrames(const TimeUnit& aTime, uint32_t aRate) {
return UsecsToFrames(aTime.ToMicroseconds(), aRate);
}
nsresult SecondsToUsecs(double aSeconds, int64_t& aOutUsecs) {
if (aSeconds * double(USECS_PER_S) > INT64_MAX) {
return NS_ERROR_FAILURE;
}
aOutUsecs = int64_t(aSeconds * double(USECS_PER_S));
return NS_OK;
}
static int32_t ConditionDimension(float aValue)
{
// This will exclude NaNs and too-big values.
if (aValue > 1.0 && aValue <= INT32_MAX)
return int32_t(NS_round(aValue));
return 0;
}
void
ScaleDisplayByAspectRatio(gfx::IntSize& aDisplay, float aAspectRatio)
{
if (aAspectRatio > 1.0) {
// Increase the intrinsic width
aDisplay.width = ConditionDimension(aAspectRatio * aDisplay.width);
} else {
// Increase the intrinsic height
aDisplay.height = ConditionDimension(aDisplay.height / aAspectRatio);
}
}
static int64_t BytesToTime(int64_t offset, int64_t length, int64_t durationUs) {
NS_ASSERTION(length > 0, "Must have positive length");
double r = double(offset) / double(length);
if (r > 1.0)
r = 1.0;
return int64_t(double(durationUs) * r);
}
media::TimeIntervals GetEstimatedBufferedTimeRanges(mozilla::MediaResource* aStream,
int64_t aDurationUsecs)
{
media::TimeIntervals buffered;
// Nothing to cache if the media takes 0us to play.
if (aDurationUsecs <= 0 || !aStream)
return buffered;
// Special case completely cached files. This also handles local files.
if (aStream->IsDataCachedToEndOfResource(0)) {
buffered +=
media::TimeInterval(TimeUnit::Zero(),
TimeUnit::FromMicroseconds(aDurationUsecs));
return buffered;
}
int64_t totalBytes = aStream->GetLength();
// If we can't determine the total size, pretend that we have nothing
// buffered. This will put us in a state of eternally-low-on-undecoded-data
// which is not great, but about the best we can do.
if (totalBytes <= 0)
return buffered;
int64_t startOffset = aStream->GetNextCachedData(0);
while (startOffset >= 0) {
int64_t endOffset = aStream->GetCachedDataEnd(startOffset);
// Bytes [startOffset..endOffset] are cached.
NS_ASSERTION(startOffset >= 0, "Integer underflow in GetBuffered");
NS_ASSERTION(endOffset >= 0, "Integer underflow in GetBuffered");
int64_t startUs = BytesToTime(startOffset, totalBytes, aDurationUsecs);
int64_t endUs = BytesToTime(endOffset, totalBytes, aDurationUsecs);
if (startUs != endUs) {
buffered +=
media::TimeInterval(TimeUnit::FromMicroseconds(startUs),
TimeUnit::FromMicroseconds(endUs));
}
startOffset = aStream->GetNextCachedData(endOffset);
}
return buffered;
}
void DownmixStereoToMono(mozilla::AudioDataValue* aBuffer,
uint32_t aFrames)
{
MOZ_ASSERT(aBuffer);
const int channels = 2;
for (uint32_t fIdx = 0; fIdx < aFrames; ++fIdx) {
#ifdef MOZ_SAMPLE_TYPE_FLOAT32
float sample = 0.0;
#else
int sample = 0;
#endif
// The sample of the buffer would be interleaved.
sample = (aBuffer[fIdx*channels] + aBuffer[fIdx*channels + 1]) * 0.5;
aBuffer[fIdx*channels] = aBuffer[fIdx*channels + 1] = sample;
}
}
bool
IsVideoContentType(const nsCString& aContentType)
{
NS_NAMED_LITERAL_CSTRING(video, "video");
if (FindInReadable(video, aContentType)) {
return true;
}
return false;
}
bool
IsValidVideoRegion(const gfx::IntSize& aFrame,
const gfx::IntRect& aPicture,
const gfx::IntSize& aDisplay)
{
return
aFrame.width <= PlanarYCbCrImage::MAX_DIMENSION &&
aFrame.height <= PlanarYCbCrImage::MAX_DIMENSION &&
aFrame.width * aFrame.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
aFrame.width * aFrame.height != 0 &&
aPicture.width <= PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.x < PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.x + aPicture.width < PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.height <= PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.y < PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.y + aPicture.height < PlanarYCbCrImage::MAX_DIMENSION &&
aPicture.width * aPicture.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
aPicture.width * aPicture.height != 0 &&
aDisplay.width <= PlanarYCbCrImage::MAX_DIMENSION &&
aDisplay.height <= PlanarYCbCrImage::MAX_DIMENSION &&
aDisplay.width * aDisplay.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
aDisplay.width * aDisplay.height != 0;
}
already_AddRefed<SharedThreadPool> GetMediaThreadPool(MediaThreadType aType)
{
const char *name;
switch (aType) {
case MediaThreadType::PLATFORM_DECODER:
name = "MediaPDecoder";
break;
case MediaThreadType::MSG_CONTROL:
name = "MSGControl";
break;
case MediaThreadType::WEBRTC_DECODER:
name = "WebRTCPD";
break;
default:
MOZ_FALLTHROUGH_ASSERT("Unexpected MediaThreadType");
case MediaThreadType::PLAYBACK:
name = "MediaPlayback";
break;
}
static const uint32_t kMediaThreadPoolDefaultCount = 4;
return SharedThreadPool::
Get(nsDependentCString(name), kMediaThreadPoolDefaultCount);
}
bool
ExtractVPXCodecDetails(const nsAString& aCodec,
uint8_t& aProfile,
uint8_t& aLevel,
uint8_t& aBitDepth)
{
uint8_t dummyChromaSubsampling = 1;
VideoColorSpace dummyColorspace;
return ExtractVPXCodecDetails(aCodec,
aProfile,
aLevel,
aBitDepth,
dummyChromaSubsampling,
dummyColorspace);
}
bool ExtractVPXCodecDetails(const nsAString& aCodec,
uint8_t& aProfile,
uint8_t& aLevel,
uint8_t& aBitDepth,
uint8_t& aChromaSubsampling,
VideoColorSpace& aColorSpace)
{
// Assign default value.
aChromaSubsampling = 1;
auto splitter = aCodec.Split(u'.');
auto fieldsItr = splitter.begin();
auto fourCC = *fieldsItr;
if (!fourCC.EqualsLiteral("vp09") && !fourCC.EqualsLiteral("vp08")) {
// Invalid 4CC
return false;
}
++fieldsItr;
uint8_t *fields[] = { &aProfile, &aLevel, &aBitDepth, &aChromaSubsampling,
&aColorSpace.mPrimaryId, &aColorSpace.mTransferId,
&aColorSpace.mMatrixId, &aColorSpace.mRangeId };
int fieldsCount = 0;
nsresult rv;
for (; fieldsItr != splitter.end(); ++fieldsItr, ++fieldsCount) {
if (fieldsCount > 7) {
// No more than 8 fields are expected.
return false;
}
*(fields[fieldsCount]) =
static_cast<uint8_t>(PromiseFlatString((*fieldsItr)).ToInteger(&rv, 10));
// We got invalid field value, parsing error.
NS_ENSURE_SUCCESS(rv, false);
}
// Mandatory Fields
// <sample entry 4CC>.<profile>.<level>.<bitDepth>.
// Optional Fields
// <chromaSubsampling>.<colourPrimaries>.<transferCharacteristics>.
// <matrixCoefficients>.<videoFullRangeFlag>
// First three fields are mandatory(we have parsed 4CC).
if (fieldsCount < 3) {
// Invalid number of fields.
return false;
}
// Start to validate the parsing value.
// profile should be 0,1,2 or 3.
// See https://www.webmproject.org/vp9/profiles/
// We don't support more than profile 2
if (aProfile > 2) {
// Invalid profile.
return false;
}
// level, See https://www.webmproject.org/vp9/mp4/#semantics_1
switch (aLevel) {
case 10:
case 11:
case 20:
case 21:
case 30:
case 31:
case 40:
case 41:
case 50:
case 51:
case 52:
case 60:
case 61:
case 62:
break;
default:
// Invalid level.
return false;
}
if (aBitDepth != 8 && aBitDepth != 10 && aBitDepth != 12) {
// Invalid bitDepth:
return false;
}
if (fieldsCount == 3) {
// No more options.
return true;
}
// chromaSubsampling should be 0,1,2,3...4~7 are reserved.
if (aChromaSubsampling > 3) {
return false;
}
if (fieldsCount == 4) {
// No more options.
return true;
}
// It is an integer that is defined by the "Colour primaries"
// section of ISO/IEC 23001-8:2016 Table 2.
// We treat reserved value as false case.
const auto& primaryId = aColorSpace.mPrimaryId;
if (primaryId == 0 || primaryId == 3 || primaryId > 22) {
// reserved value.
return false;
}
if (primaryId > 12 && primaryId < 22) {
// 13~21 are reserved values.
return false;
}
if (fieldsCount == 5) {
// No more options.
return true;
}
// It is an integer that is defined by the
// "Transfer characteristics" section of ISO/IEC 23001-8:2016 Table 3.
// We treat reserved value as false case.
const auto& transferId = aColorSpace.mTransferId;
if (transferId == 0 || transferId == 3 || transferId > 18) {
// reserved value.
return false;
}
if (fieldsCount == 6) {
// No more options.
return true;
}
// It is an integer that is defined by the
// "Matrix coefficients" section of ISO/IEC 23001-8:2016 Table 4.
// We treat reserved value as false case.
const auto& matrixId = aColorSpace.mMatrixId;
if (matrixId == 3 || matrixId > 11) {
return false;
}
// If matrixCoefficients is 0 (RGB), then chroma subsampling MUST be 3 (4:4:4).
if (matrixId == 0 && aChromaSubsampling != 3) {
return false;
}
if (fieldsCount == 7) {
// No more options.
return true;
}
// videoFullRangeFlag indicates the black level and range of the luma and
// chroma signals. 0 = legal range (e.g. 16-235 for 8 bit sample depth);
// 1 = full range (e.g. 0-255 for 8-bit sample depth).
const auto& rangeId = aColorSpace.mRangeId;
return rangeId <= 1;
}
bool
ExtractH264CodecDetails(const nsAString& aCodec,
int16_t& aProfile,
int16_t& aLevel)
{
// H.264 codecs parameters have a type defined as avcN.PPCCLL, where
// N = avc type. avc3 is avcc with SPS & PPS implicit (within stream)
// PP = profile_idc, CC = constraint_set flags, LL = level_idc.
// We ignore the constraint_set flags, as it's not clear from any
// documentation what constraints the platform decoders support.
// See http://blog.pearce.org.nz/2013/11/what-does-h264avc1-codecs-parameters.html
// for more details.
if (aCodec.Length() != strlen("avc1.PPCCLL")) {
return false;
}
// Verify the codec starts with "avc1." or "avc3.".
const nsAString& sample = Substring(aCodec, 0, 5);
if (!sample.EqualsASCII("avc1.") && !sample.EqualsASCII("avc3.")) {
return false;
}
// Extract the profile_idc and level_idc.
nsresult rv = NS_OK;
aProfile = PromiseFlatString(Substring(aCodec, 5, 2)).ToInteger(&rv, 16);
NS_ENSURE_SUCCESS(rv, false);
aLevel = PromiseFlatString(Substring(aCodec, 9, 2)).ToInteger(&rv, 16);
NS_ENSURE_SUCCESS(rv, false);
if (aLevel == 9) {
aLevel = H264_LEVEL_1_b;
} else if (aLevel <= 5) {
aLevel *= 10;
}
// Capture the constraint_set flag value for the purpose of Telemetry.
// We don't NS_ENSURE_SUCCESS here because ExtractH264CodecDetails doesn't
// care about this, but we make sure constraints is above 4 (constraint_set5_flag)
// otherwise collect 0 for unknown.
uint8_t constraints = PromiseFlatString(Substring(aCodec, 7, 2)).ToInteger(&rv, 16);
Telemetry::Accumulate(Telemetry::VIDEO_CANPLAYTYPE_H264_CONSTRAINT_SET_FLAG,
constraints >= 4 ? constraints : 0);
// 244 is the highest meaningful profile value (High 4:4:4 Intra Profile)
// that can be represented as single hex byte, otherwise collect 0 for unknown.
Telemetry::Accumulate(Telemetry::VIDEO_CANPLAYTYPE_H264_PROFILE,
aProfile <= 244 ? aProfile : 0);
// Make sure aLevel represents a value between levels 1 and 5.2,
// otherwise collect 0 for unknown.
Telemetry::Accumulate(Telemetry::VIDEO_CANPLAYTYPE_H264_LEVEL,
(aLevel >= 10 && aLevel <= 52) ? aLevel : 0);
return true;
}
nsresult
GenerateRandomName(nsCString& aOutSalt, uint32_t aLength)
{
nsresult rv;
nsCOMPtr<nsIRandomGenerator> rg =
do_GetService("@mozilla.org/security/random-generator;1", &rv);
if (NS_FAILED(rv)) return rv;
// For each three bytes of random data we will get four bytes of ASCII.
const uint32_t requiredBytesLength =
static_cast<uint32_t>((aLength + 3) / 4 * 3);
uint8_t* buffer;
rv = rg->GenerateRandomBytes(requiredBytesLength, &buffer);
if (NS_FAILED(rv)) return rv;
nsAutoCString temp;
nsDependentCSubstring randomData(reinterpret_cast<const char*>(buffer),
requiredBytesLength);
rv = Base64Encode(randomData, temp);
free(buffer);
buffer = nullptr;
if (NS_FAILED (rv)) return rv;
aOutSalt = temp;
return NS_OK;
}
nsresult
GenerateRandomPathName(nsCString& aOutSalt, uint32_t aLength)
{
nsresult rv = GenerateRandomName(aOutSalt, aLength);
if (NS_FAILED(rv)) return rv;
// Base64 characters are alphanumeric (a-zA-Z0-9) and '+' and '/', so we need
// to replace illegal characters -- notably '/'
aOutSalt.ReplaceChar(FILE_PATH_SEPARATOR FILE_ILLEGAL_CHARACTERS, '_');
return NS_OK;
}
already_AddRefed<TaskQueue>
CreateMediaDecodeTaskQueue(const char* aName)
{
RefPtr<TaskQueue> queue = new TaskQueue(
GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER), aName);
return queue.forget();
}
void
SimpleTimer::Cancel() {
if (mTimer) {
#ifdef DEBUG
nsCOMPtr<nsIEventTarget> target;
mTimer->GetTarget(getter_AddRefs(target));
bool onCurrent;
nsresult rv = target->IsOnCurrentThread(&onCurrent);
MOZ_ASSERT(NS_SUCCEEDED(rv) && onCurrent);
#endif
mTimer->Cancel();
mTimer = nullptr;
}
mTask = nullptr;
}
NS_IMETHODIMP
SimpleTimer::Notify(nsITimer *timer) {
RefPtr<SimpleTimer> deathGrip(this);
if (mTask) {
mTask->Run();
mTask = nullptr;
}
return NS_OK;
}
NS_IMETHODIMP
SimpleTimer::GetName(nsACString& aName)
{
aName.AssignLiteral("SimpleTimer");
return NS_OK;
}
nsresult
SimpleTimer::Init(nsIRunnable* aTask, uint32_t aTimeoutMs, nsIEventTarget* aTarget)
{
nsresult rv;
// Get target thread first, so we don't have to cancel the timer if it fails.
nsCOMPtr<nsIEventTarget> target;
if (aTarget) {
target = aTarget;
} else {
target = GetMainThreadEventTarget();
if (!target) {
return NS_ERROR_NOT_AVAILABLE;
}
}
rv = NS_NewTimerWithCallback(getter_AddRefs(mTimer),
this, aTimeoutMs, nsITimer::TYPE_ONE_SHOT,
target);
if (NS_FAILED(rv)) {
return rv;
}
mTask = aTask;
return NS_OK;
}
NS_IMPL_ISUPPORTS(SimpleTimer, nsITimerCallback, nsINamed)
already_AddRefed<SimpleTimer>
SimpleTimer::Create(nsIRunnable* aTask, uint32_t aTimeoutMs, nsIEventTarget* aTarget)
{
RefPtr<SimpleTimer> t(new SimpleTimer());
if (NS_FAILED(t->Init(aTask, aTimeoutMs, aTarget))) {
return nullptr;
}
return t.forget();
}
void
LogToBrowserConsole(const nsAString& aMsg)
{
if (!NS_IsMainThread()) {
nsString msg(aMsg);
nsCOMPtr<nsIRunnable> task = NS_NewRunnableFunction(
"LogToBrowserConsole", [msg]() { LogToBrowserConsole(msg); });
SystemGroup::Dispatch(TaskCategory::Other, task.forget());
return;
}
nsCOMPtr<nsIConsoleService> console(
do_GetService("@mozilla.org/consoleservice;1"));
if (!console) {
NS_WARNING("Failed to log message to console.");
return;
}
nsAutoString msg(aMsg);
console->LogStringMessage(msg.get());
}
bool
ParseCodecsString(const nsAString& aCodecs, nsTArray<nsString>& aOutCodecs)
{
aOutCodecs.Clear();
bool expectMoreTokens = false;
nsCharSeparatedTokenizer tokenizer(aCodecs, ',');
while (tokenizer.hasMoreTokens()) {
const nsAString& token = tokenizer.nextToken();
expectMoreTokens = tokenizer.separatorAfterCurrentToken();
aOutCodecs.AppendElement(token);
}
if (expectMoreTokens) {
// Last codec name was empty
return false;
}
return true;
}
bool
ParseMIMETypeString(const nsAString& aMIMEType,
nsString& aOutContainerType,
nsTArray<nsString>& aOutCodecs)
{
nsContentTypeParser parser(aMIMEType);
nsresult rv = parser.GetType(aOutContainerType);
if (NS_FAILED(rv)) {
return false;
}
nsString codecsStr;
parser.GetParameter("codecs", codecsStr);
return ParseCodecsString(codecsStr, aOutCodecs);
}
template <int N>
static bool
StartsWith(const nsACString& string, const char (&prefix)[N])
{
if (N - 1 > string.Length()) {
return false;
}
return memcmp(string.Data(), prefix, N - 1) == 0;
}
bool
IsH264CodecString(const nsAString& aCodec)
{
int16_t profile = 0;
int16_t level = 0;
return ExtractH264CodecDetails(aCodec, profile, level);
}
bool
IsAACCodecString(const nsAString& aCodec)
{
return
aCodec.EqualsLiteral("mp4a.40.2") || // MPEG4 AAC-LC
aCodec.EqualsLiteral("mp4a.40.02") || // MPEG4 AAC-LC(for compatibility)
aCodec.EqualsLiteral("mp4a.40.5") || // MPEG4 HE-AAC
aCodec.EqualsLiteral("mp4a.40.05") || // MPEG4 HE-AAC(for compatibility)
aCodec.EqualsLiteral("mp4a.67") || // MPEG2 AAC-LC
aCodec.EqualsLiteral("mp4a.40.29"); // MPEG4 HE-AACv2
}
bool
IsVP8CodecString(const nsAString& aCodec)
{
uint8_t profile = 0;
uint8_t level = 0;
uint8_t bitDepth = 0;
return aCodec.EqualsLiteral("vp8") ||
aCodec.EqualsLiteral("vp8.0") ||
(StartsWith(NS_ConvertUTF16toUTF8(aCodec), "vp08") &&
ExtractVPXCodecDetails(aCodec, profile, level, bitDepth));
}
bool
IsVP9CodecString(const nsAString& aCodec)
{
uint8_t profile = 0;
uint8_t level = 0;
uint8_t bitDepth = 0;
return aCodec.EqualsLiteral("vp9") ||
aCodec.EqualsLiteral("vp9.0") ||
(StartsWith(NS_ConvertUTF16toUTF8(aCodec), "vp09") &&
ExtractVPXCodecDetails(aCodec, profile, level, bitDepth));
}
UniquePtr<TrackInfo>
CreateTrackInfoWithMIMEType(const nsACString& aCodecMIMEType)
{
UniquePtr<TrackInfo> trackInfo;
if (StartsWith(aCodecMIMEType, "audio/")) {
trackInfo.reset(new AudioInfo());
trackInfo->mMimeType = aCodecMIMEType;
} else if (StartsWith(aCodecMIMEType, "video/")) {
trackInfo.reset(new VideoInfo());
trackInfo->mMimeType = aCodecMIMEType;
}
return trackInfo;
}
UniquePtr<TrackInfo>
CreateTrackInfoWithMIMETypeAndContainerTypeExtraParameters(
const nsACString& aCodecMIMEType,
const MediaContainerType& aContainerType)
{
UniquePtr<TrackInfo> trackInfo = CreateTrackInfoWithMIMEType(aCodecMIMEType);
if (trackInfo) {
VideoInfo* videoInfo = trackInfo->GetAsVideoInfo();
if (videoInfo) {
Maybe<int32_t> maybeWidth = aContainerType.ExtendedType().GetWidth();
if (maybeWidth && *maybeWidth > 0) {
videoInfo->mImage.width = *maybeWidth;
}
Maybe<int32_t> maybeHeight = aContainerType.ExtendedType().GetHeight();
if (maybeHeight && *maybeHeight > 0) {
videoInfo->mImage.height = *maybeHeight;
}
}
}
return trackInfo;
}
} // end namespace mozilla