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MP3Demuxer.cpp
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MP3Demuxer.cpp
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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* 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 "MP3Demuxer.h"
#include <inttypes.h>
#include <algorithm>
#include "mozilla/Assertions.h"
#include "mozilla/EndianUtils.h"
#include "mozilla/SizePrintfMacros.h"
#include "nsAutoPtr.h"
#include "VideoUtils.h"
#include "TimeUnits.h"
#include "prenv.h"
extern mozilla::LazyLogModule gMediaDemuxerLog;
#define MP3LOG(msg, ...) \
MOZ_LOG(gMediaDemuxerLog, LogLevel::Debug, ("MP3Demuxer " msg, ##__VA_ARGS__))
#define MP3LOGV(msg, ...) \
MOZ_LOG(gMediaDemuxerLog, LogLevel::Verbose, ("MP3Demuxer " msg, ##__VA_ARGS__))
using mozilla::media::TimeUnit;
using mozilla::media::TimeInterval;
using mozilla::media::TimeIntervals;
using mp4_demuxer::ByteReader;
namespace mozilla {
namespace mp3 {
// MP3Demuxer
MP3Demuxer::MP3Demuxer(MediaResource* aSource) : mSource(aSource) { }
bool
MP3Demuxer::InitInternal()
{
if (!mTrackDemuxer) {
mTrackDemuxer = new MP3TrackDemuxer(mSource);
}
return mTrackDemuxer->Init();
}
RefPtr<MP3Demuxer::InitPromise>
MP3Demuxer::Init()
{
if (!InitInternal()) {
MP3LOG("MP3Demuxer::Init() failure: waiting for data");
return InitPromise::CreateAndReject(
NS_ERROR_DOM_MEDIA_METADATA_ERR, __func__);
}
MP3LOG("MP3Demuxer::Init() successful");
return InitPromise::CreateAndResolve(NS_OK, __func__);
}
bool
MP3Demuxer::HasTrackType(TrackInfo::TrackType aType) const
{
return aType == TrackInfo::kAudioTrack;
}
uint32_t
MP3Demuxer::GetNumberTracks(TrackInfo::TrackType aType) const
{
return aType == TrackInfo::kAudioTrack ? 1u : 0u;
}
already_AddRefed<MediaTrackDemuxer>
MP3Demuxer::GetTrackDemuxer(TrackInfo::TrackType aType, uint32_t aTrackNumber)
{
if (!mTrackDemuxer) {
return nullptr;
}
return RefPtr<MP3TrackDemuxer>(mTrackDemuxer).forget();
}
bool
MP3Demuxer::IsSeekable() const
{
return true;
}
void
MP3Demuxer::NotifyDataArrived()
{
// TODO: bug 1169485.
NS_WARNING("Unimplemented function NotifyDataArrived");
MP3LOGV("NotifyDataArrived()");
}
void
MP3Demuxer::NotifyDataRemoved()
{
// TODO: bug 1169485.
NS_WARNING("Unimplemented function NotifyDataRemoved");
MP3LOGV("NotifyDataRemoved()");
}
// MP3TrackDemuxer
MP3TrackDemuxer::MP3TrackDemuxer(MediaResource* aSource)
: mSource(aSource)
, mOffset(0)
, mFirstFrameOffset(0)
, mNumParsedFrames(0)
, mFrameIndex(0)
, mTotalFrameLen(0)
, mSamplesPerFrame(0)
, mSamplesPerSecond(0)
, mChannels(0)
{
Reset();
}
bool
MP3TrackDemuxer::Init()
{
Reset();
FastSeek(TimeUnit());
// Read the first frame to fetch sample rate and other meta data.
RefPtr<MediaRawData> frame(GetNextFrame(FindFirstFrame()));
MP3LOG("Init StreamLength()=%" PRId64 " first-frame-found=%d",
StreamLength(), !!frame);
if (!frame) {
return false;
}
// Rewind back to the stream begin to avoid dropping the first frame.
FastSeek(TimeUnit());
if (!mInfo) {
mInfo = MakeUnique<AudioInfo>();
}
mInfo->mRate = mSamplesPerSecond;
mInfo->mChannels = mChannels;
mInfo->mBitDepth = 16;
mInfo->mMimeType = "audio/mpeg";
mInfo->mDuration = Duration();
MP3LOG("Init mInfo={mRate=%d mChannels=%d mBitDepth=%d mDuration=%" PRId64 "}",
mInfo->mRate, mInfo->mChannels, mInfo->mBitDepth,
mInfo->mDuration.ToMicroseconds());
return mSamplesPerSecond && mChannels;
}
media::TimeUnit
MP3TrackDemuxer::SeekPosition() const
{
TimeUnit pos = Duration(mFrameIndex);
if (Duration() > TimeUnit()) {
pos = std::min(Duration(), pos);
}
return pos;
}
const FrameParser::Frame&
MP3TrackDemuxer::LastFrame() const
{
return mParser.PrevFrame();
}
RefPtr<MediaRawData>
MP3TrackDemuxer::DemuxSample()
{
return GetNextFrame(FindNextFrame());
}
const ID3Parser::ID3Header&
MP3TrackDemuxer::ID3Header() const
{
return mParser.ID3Header();
}
const FrameParser::VBRHeader&
MP3TrackDemuxer::VBRInfo() const
{
return mParser.VBRInfo();
}
UniquePtr<TrackInfo>
MP3TrackDemuxer::GetInfo() const
{
return mInfo->Clone();
}
RefPtr<MP3TrackDemuxer::SeekPromise>
MP3TrackDemuxer::Seek(const TimeUnit& aTime)
{
// Efficiently seek to the position.
FastSeek(aTime);
// Correct seek position by scanning the next frames.
const TimeUnit seekTime = ScanUntil(aTime);
return SeekPromise::CreateAndResolve(seekTime, __func__);
}
TimeUnit
MP3TrackDemuxer::FastSeek(const TimeUnit& aTime)
{
MP3LOG("FastSeek(%" PRId64 ") avgFrameLen=%f mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mOffset=%" PRIu64,
aTime.ToMicroseconds(), AverageFrameLength(), mNumParsedFrames,
mFrameIndex, mOffset);
const auto& vbr = mParser.VBRInfo();
if (!aTime.ToMicroseconds()) {
// Quick seek to the beginning of the stream.
mFrameIndex = 0;
} else if (vbr.IsTOCPresent() && Duration().ToMicroseconds() > 0) {
// Use TOC for more precise seeking.
const float durationFrac = static_cast<float>(aTime.ToMicroseconds()) /
Duration().ToMicroseconds();
mFrameIndex = FrameIndexFromOffset(vbr.Offset(durationFrac));
} else if (AverageFrameLength() > 0) {
mFrameIndex = FrameIndexFromTime(aTime);
}
mOffset = OffsetFromFrameIndex(mFrameIndex);
if (mOffset > mFirstFrameOffset && StreamLength() > 0) {
mOffset = std::min(StreamLength() - 1, mOffset);
}
mParser.EndFrameSession();
MP3LOG("FastSeek End TOC=%d avgFrameLen=%f mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mFirstFrameOffset=%" PRId64 " mOffset=%" PRIu64
" SL=%" PRId64 " NumBytes=%u",
vbr.IsTOCPresent(), AverageFrameLength(), mNumParsedFrames, mFrameIndex,
mFirstFrameOffset, mOffset, StreamLength(), vbr.NumBytes().valueOr(0));
return Duration(mFrameIndex);
}
TimeUnit
MP3TrackDemuxer::ScanUntil(const TimeUnit& aTime)
{
MP3LOG("ScanUntil(%" PRId64 ") avgFrameLen=%f mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mOffset=%" PRIu64,
aTime.ToMicroseconds(), AverageFrameLength(), mNumParsedFrames,
mFrameIndex, mOffset);
if (!aTime.ToMicroseconds()) {
return FastSeek(aTime);
}
if (Duration(mFrameIndex) > aTime) {
// We've seeked past the target time, rewind back a little to correct it.
const int64_t rewind = aTime.ToMicroseconds() / 100;
FastSeek(aTime - TimeUnit::FromMicroseconds(rewind));
}
if (Duration(mFrameIndex + 1) > aTime) {
return SeekPosition();
}
MediaByteRange nextRange = FindNextFrame();
while (SkipNextFrame(nextRange) && Duration(mFrameIndex + 1) < aTime) {
nextRange = FindNextFrame();
MP3LOGV("ScanUntil* avgFrameLen=%f mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mOffset=%" PRIu64 " Duration=%" PRId64,
AverageFrameLength(), mNumParsedFrames,
mFrameIndex, mOffset, Duration(mFrameIndex + 1).ToMicroseconds());
}
MP3LOG("ScanUntil End avgFrameLen=%f mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mOffset=%" PRIu64,
AverageFrameLength(), mNumParsedFrames, mFrameIndex, mOffset);
return SeekPosition();
}
RefPtr<MP3TrackDemuxer::SamplesPromise>
MP3TrackDemuxer::GetSamples(int32_t aNumSamples)
{
MP3LOGV("GetSamples(%d) Begin mOffset=%" PRIu64 " mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mTotalFrameLen=%" PRIu64
" mSamplesPerFrame=%d mSamplesPerSecond=%d mChannels=%d",
aNumSamples, mOffset, mNumParsedFrames, mFrameIndex, mTotalFrameLen,
mSamplesPerFrame, mSamplesPerSecond, mChannels);
if (!aNumSamples) {
return SamplesPromise::CreateAndReject(
NS_ERROR_DOM_MEDIA_DEMUXER_ERR, __func__);
}
RefPtr<SamplesHolder> frames = new SamplesHolder();
while (aNumSamples--) {
RefPtr<MediaRawData> frame(GetNextFrame(FindNextFrame()));
if (!frame) {
break;
}
frames->mSamples.AppendElement(frame);
}
MP3LOGV("GetSamples() End mSamples.Size()=%" PRIuSIZE " aNumSamples=%d mOffset=%" PRIu64
" mNumParsedFrames=%" PRIu64 " mFrameIndex=%" PRId64
" mTotalFrameLen=%" PRIu64 " mSamplesPerFrame=%d mSamplesPerSecond=%d "
"mChannels=%d",
frames->mSamples.Length(), aNumSamples, mOffset, mNumParsedFrames,
mFrameIndex, mTotalFrameLen, mSamplesPerFrame, mSamplesPerSecond,
mChannels);
if (frames->mSamples.IsEmpty()) {
return SamplesPromise::CreateAndReject(
NS_ERROR_DOM_MEDIA_END_OF_STREAM, __func__);
}
return SamplesPromise::CreateAndResolve(frames, __func__);
}
void
MP3TrackDemuxer::Reset()
{
MP3LOG("Reset()");
FastSeek(TimeUnit());
mParser.Reset();
}
RefPtr<MP3TrackDemuxer::SkipAccessPointPromise>
MP3TrackDemuxer::SkipToNextRandomAccessPoint(const TimeUnit& aTimeThreshold)
{
// Will not be called for audio-only resources.
return SkipAccessPointPromise::CreateAndReject(
SkipFailureHolder(NS_ERROR_DOM_MEDIA_DEMUXER_ERR, 0), __func__);
}
int64_t
MP3TrackDemuxer::GetResourceOffset() const
{
return mOffset;
}
TimeIntervals
MP3TrackDemuxer::GetBuffered()
{
AutoPinned<MediaResource> stream(mSource.GetResource());
TimeIntervals buffered;
if (Duration() > TimeUnit() && stream->IsDataCachedToEndOfResource(0)) {
// Special case completely cached files. This also handles local files.
buffered += TimeInterval(TimeUnit(), Duration());
MP3LOGV("buffered = [[%" PRId64 ", %" PRId64 "]]",
TimeUnit().ToMicroseconds(), Duration().ToMicroseconds());
return buffered;
}
MediaByteRangeSet ranges;
nsresult rv = stream->GetCachedRanges(ranges);
NS_ENSURE_SUCCESS(rv, buffered);
for (const auto& range: ranges) {
if (range.IsEmpty()) {
continue;
}
TimeUnit start = Duration(FrameIndexFromOffset(range.mStart));
TimeUnit end = Duration(FrameIndexFromOffset(range.mEnd));
MP3LOGV("buffered += [%" PRId64 ", %" PRId64 "]",
start.ToMicroseconds(), end.ToMicroseconds());
buffered += TimeInterval(start, end);
}
return buffered;
}
int64_t
MP3TrackDemuxer::StreamLength() const
{
return mSource.GetLength();
}
TimeUnit
MP3TrackDemuxer::Duration() const
{
if (!mNumParsedFrames) {
return TimeUnit::FromMicroseconds(-1);
}
int64_t numFrames = 0;
const auto numAudioFrames = mParser.VBRInfo().NumAudioFrames();
if (mParser.VBRInfo().IsValid() && numAudioFrames.valueOr(0) + 1 > 1) {
// VBR headers don't include the VBR header frame.
numFrames = numAudioFrames.value() + 1;
} else {
const int64_t streamLen = StreamLength();
if (streamLen < 0) {
// Unknown length, we can't estimate duration.
return TimeUnit::FromMicroseconds(-1);
}
if (AverageFrameLength() > 0) {
numFrames = (streamLen - mFirstFrameOffset) / AverageFrameLength();
}
}
return Duration(numFrames);
}
TimeUnit
MP3TrackDemuxer::Duration(int64_t aNumFrames) const
{
if (!mSamplesPerSecond) {
return TimeUnit::FromMicroseconds(-1);
}
const double usPerFrame = USECS_PER_S * mSamplesPerFrame / mSamplesPerSecond;
return TimeUnit::FromMicroseconds(aNumFrames * usPerFrame);
}
MediaByteRange
MP3TrackDemuxer::FindFirstFrame()
{
static const int MIN_SUCCESSIVE_FRAMES = 4;
MediaByteRange candidateFrame = FindNextFrame();
int numSuccFrames = candidateFrame.Length() > 0;
MediaByteRange currentFrame = candidateFrame;
MP3LOGV("FindFirst() first candidate frame: mOffset=%" PRIu64
" Length()=%" PRIu64,
candidateFrame.mStart, candidateFrame.Length());
while (candidateFrame.Length() && numSuccFrames < MIN_SUCCESSIVE_FRAMES) {
mParser.EndFrameSession();
mOffset = currentFrame.mEnd;
const MediaByteRange prevFrame = currentFrame;
// FindNextFrame() here will only return frames consistent with our candidate frame.
currentFrame = FindNextFrame();
numSuccFrames += currentFrame.Length() > 0;
// Multiple successive false positives, which wouldn't be caught by the consistency
// checks alone, can be detected by wrong alignment (non-zero gap between frames).
const int64_t frameSeparation = currentFrame.mStart - prevFrame.mEnd;
if (!currentFrame.Length() || frameSeparation != 0) {
MP3LOGV("FindFirst() not enough successive frames detected, "
"rejecting candidate frame: successiveFrames=%d, last "
"Length()=%" PRIu64 ", last frameSeparation=%" PRId64,
numSuccFrames, currentFrame.Length(), frameSeparation);
mParser.ResetFrameData();
mOffset = candidateFrame.mStart + 1;
candidateFrame = FindNextFrame();
numSuccFrames = candidateFrame.Length() > 0;
currentFrame = candidateFrame;
MP3LOGV("FindFirst() new candidate frame: mOffset=%" PRIu64
" Length()=%" PRIu64,
candidateFrame.mStart, candidateFrame.Length());
}
}
if (numSuccFrames >= MIN_SUCCESSIVE_FRAMES) {
MP3LOG("FindFirst() accepting candidate frame: "
"successiveFrames=%d", numSuccFrames);
} else {
MP3LOG("FindFirst() no suitable first frame found");
}
return candidateFrame;
}
static bool
VerifyFrameConsistency(const FrameParser::Frame& aFrame1,
const FrameParser::Frame& aFrame2)
{
const auto& h1 = aFrame1.Header();
const auto& h2 = aFrame2.Header();
return h1.IsValid()
&& h2.IsValid()
&& h1.Layer() == h2.Layer()
&& h1.SlotSize() == h2.SlotSize()
&& h1.SamplesPerFrame() == h2.SamplesPerFrame()
&& h1.Channels() == h2.Channels()
&& h1.SampleRate() == h2.SampleRate()
&& h1.RawVersion() == h2.RawVersion()
&& h1.RawProtection() == h2.RawProtection();
}
MediaByteRange
MP3TrackDemuxer::FindNextFrame()
{
static const int BUFFER_SIZE = 64;
static const int MAX_SKIPPED_BYTES = 1024 * BUFFER_SIZE;
MP3LOGV("FindNext() Begin mOffset=%" PRIu64 " mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mTotalFrameLen=%" PRIu64
" mSamplesPerFrame=%d mSamplesPerSecond=%d mChannels=%d",
mOffset, mNumParsedFrames, mFrameIndex, mTotalFrameLen,
mSamplesPerFrame, mSamplesPerSecond, mChannels);
uint8_t buffer[BUFFER_SIZE];
int32_t read = 0;
bool foundFrame = false;
int64_t frameHeaderOffset = 0;
// Check whether we've found a valid MPEG frame.
while (!foundFrame) {
if ((!mParser.FirstFrame().Length()
&& mOffset - mParser.ID3Header().Size() > MAX_SKIPPED_BYTES)
|| (read = Read(buffer, mOffset, BUFFER_SIZE)) == 0) {
MP3LOG("FindNext() EOS or exceeded MAX_SKIPPED_BYTES without a frame");
// This is not a valid MPEG audio stream or we've reached EOS, give up.
break;
}
ByteReader reader(buffer, read);
uint32_t bytesToSkip = 0;
foundFrame = mParser.Parse(&reader, &bytesToSkip);
frameHeaderOffset =
mOffset + reader.Offset() - FrameParser::FrameHeader::SIZE;
// If we've found neither an MPEG frame header nor an ID3v2 tag,
// the reader shouldn't have any bytes remaining.
MOZ_ASSERT(foundFrame || bytesToSkip || !reader.Remaining());
if (foundFrame && mParser.FirstFrame().Length()
&& !VerifyFrameConsistency(mParser.FirstFrame(),
mParser.CurrentFrame())) {
// We've likely hit a false-positive, ignore it and proceed with the
// search for the next valid frame.
foundFrame = false;
mOffset = frameHeaderOffset + 1;
mParser.EndFrameSession();
} else {
// Advance mOffset by the amount of bytes read and if necessary,
// skip an ID3v2 tag which stretches beyond the current buffer.
NS_ENSURE_TRUE(mOffset + read + bytesToSkip > mOffset,
MediaByteRange(0, 0));
mOffset += read + bytesToSkip;
}
}
if (!foundFrame || !mParser.CurrentFrame().Length()) {
MP3LOG("FindNext() Exit foundFrame=%d mParser.CurrentFrame().Length()=%d ",
foundFrame, mParser.CurrentFrame().Length());
return { 0, 0 };
}
MP3LOGV("FindNext() End mOffset=%" PRIu64 " mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " frameHeaderOffset=%" PRId64
" mTotalFrameLen=%" PRIu64 " mSamplesPerFrame=%d mSamplesPerSecond=%d"
" mChannels=%d",
mOffset, mNumParsedFrames, mFrameIndex, frameHeaderOffset,
mTotalFrameLen, mSamplesPerFrame, mSamplesPerSecond, mChannels);
return { frameHeaderOffset, frameHeaderOffset + mParser.CurrentFrame().Length() };
}
bool
MP3TrackDemuxer::SkipNextFrame(const MediaByteRange& aRange)
{
if (!mNumParsedFrames || !aRange.Length()) {
// We can't skip the first frame, since it could contain VBR headers.
RefPtr<MediaRawData> frame(GetNextFrame(aRange));
return frame;
}
UpdateState(aRange);
MP3LOGV("SkipNext() End mOffset=%" PRIu64 " mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mTotalFrameLen=%" PRIu64
" mSamplesPerFrame=%d mSamplesPerSecond=%d mChannels=%d",
mOffset, mNumParsedFrames, mFrameIndex, mTotalFrameLen,
mSamplesPerFrame, mSamplesPerSecond, mChannels);
return true;
}
already_AddRefed<MediaRawData>
MP3TrackDemuxer::GetNextFrame(const MediaByteRange& aRange)
{
MP3LOG("GetNext() Begin({mStart=%" PRId64 " Length()=%" PRId64 "})",
aRange.mStart, aRange.Length());
if (!aRange.Length()) {
return nullptr;
}
RefPtr<MediaRawData> frame = new MediaRawData();
frame->mOffset = aRange.mStart;
nsAutoPtr<MediaRawDataWriter> frameWriter(frame->CreateWriter());
if (!frameWriter->SetSize(aRange.Length())) {
MP3LOG("GetNext() Exit failed to allocated media buffer");
return nullptr;
}
const uint32_t read =
Read(frameWriter->Data(), frame->mOffset, frame->Size());
if (read != aRange.Length()) {
MP3LOG("GetNext() Exit read=%u frame->Size()=%" PRIuSIZE, read, frame->Size());
return nullptr;
}
UpdateState(aRange);
frame->mTime = Duration(mFrameIndex - 1);
frame->mDuration = Duration(1);
frame->mTimecode = frame->mTime;
frame->mKeyframe = true;
MOZ_ASSERT(!frame->mTime.IsNegative());
MOZ_ASSERT(frame->mDuration.IsPositive());
if (mNumParsedFrames == 1) {
// First frame parsed, let's read VBR info if available.
ByteReader reader(frame->Data(), frame->Size());
mParser.ParseVBRHeader(&reader);
mFirstFrameOffset = frame->mOffset;
}
MP3LOGV("GetNext() End mOffset=%" PRIu64 " mNumParsedFrames=%" PRIu64
" mFrameIndex=%" PRId64 " mTotalFrameLen=%" PRIu64
" mSamplesPerFrame=%d mSamplesPerSecond=%d mChannels=%d",
mOffset, mNumParsedFrames, mFrameIndex, mTotalFrameLen,
mSamplesPerFrame, mSamplesPerSecond, mChannels);
return frame.forget();
}
int64_t
MP3TrackDemuxer::OffsetFromFrameIndex(int64_t aFrameIndex) const
{
int64_t offset = 0;
const auto& vbr = mParser.VBRInfo();
if (vbr.IsComplete()) {
offset = mFirstFrameOffset
+ aFrameIndex * vbr.NumBytes().value()
/ vbr.NumAudioFrames().value();
} else if (AverageFrameLength() > 0) {
offset = mFirstFrameOffset + aFrameIndex * AverageFrameLength();
}
MP3LOGV("OffsetFromFrameIndex(%" PRId64 ") -> %" PRId64, aFrameIndex, offset);
return std::max<int64_t>(mFirstFrameOffset, offset);
}
int64_t
MP3TrackDemuxer::FrameIndexFromOffset(int64_t aOffset) const
{
int64_t frameIndex = 0;
const auto& vbr = mParser.VBRInfo();
if (vbr.IsComplete()) {
frameIndex = static_cast<float>(aOffset - mFirstFrameOffset)
/ vbr.NumBytes().value()
* vbr.NumAudioFrames().value();
frameIndex = std::min<int64_t>(vbr.NumAudioFrames().value(), frameIndex);
} else if (AverageFrameLength() > 0) {
frameIndex = (aOffset - mFirstFrameOffset) / AverageFrameLength();
}
MP3LOGV("FrameIndexFromOffset(%" PRId64 ") -> %" PRId64, aOffset, frameIndex);
return std::max<int64_t>(0, frameIndex);
}
int64_t
MP3TrackDemuxer::FrameIndexFromTime(const media::TimeUnit& aTime) const
{
int64_t frameIndex = 0;
if (mSamplesPerSecond > 0 && mSamplesPerFrame > 0) {
frameIndex = aTime.ToSeconds() * mSamplesPerSecond / mSamplesPerFrame - 1;
}
MP3LOGV("FrameIndexFromOffset(%fs) -> %" PRId64, aTime.ToSeconds(),
frameIndex);
return std::max<int64_t>(0, frameIndex);
}
void
MP3TrackDemuxer::UpdateState(const MediaByteRange& aRange)
{
// Prevent overflow.
if (mTotalFrameLen + aRange.Length() < mTotalFrameLen) {
// These variables have a linear dependency and are only used to derive the
// average frame length.
mTotalFrameLen /= 2;
mNumParsedFrames /= 2;
}
// Full frame parsed, move offset to its end.
mOffset = aRange.mEnd;
mTotalFrameLen += aRange.Length();
if (!mSamplesPerFrame) {
mSamplesPerFrame = mParser.CurrentFrame().Header().SamplesPerFrame();
mSamplesPerSecond = mParser.CurrentFrame().Header().SampleRate();
mChannels = mParser.CurrentFrame().Header().Channels();
}
++mNumParsedFrames;
++mFrameIndex;
MOZ_ASSERT(mFrameIndex > 0);
// Prepare the parser for the next frame parsing session.
mParser.EndFrameSession();
}
int32_t
MP3TrackDemuxer::Read(uint8_t* aBuffer, int64_t aOffset, int32_t aSize)
{
MP3LOGV("MP3TrackDemuxer::Read(%p %" PRId64 " %d)", aBuffer, aOffset, aSize);
const int64_t streamLen = StreamLength();
if (mInfo && streamLen > 0) {
// Prevent blocking reads after successful initialization.
aSize = std::min<int64_t>(aSize, streamLen - aOffset);
}
uint32_t read = 0;
MP3LOGV("MP3TrackDemuxer::Read -> ReadAt(%d)", aSize);
const nsresult rv = mSource.ReadAt(aOffset, reinterpret_cast<char*>(aBuffer),
static_cast<uint32_t>(aSize), &read);
NS_ENSURE_SUCCESS(rv, 0);
return static_cast<int32_t>(read);
}
double
MP3TrackDemuxer::AverageFrameLength() const
{
if (mNumParsedFrames) {
return static_cast<double>(mTotalFrameLen) / mNumParsedFrames;
}
const auto& vbr = mParser.VBRInfo();
if (vbr.IsComplete() && vbr.NumAudioFrames().value() + 1) {
return static_cast<double>(vbr.NumBytes().value())
/ (vbr.NumAudioFrames().value() + 1);
}
return 0.0;
}
// FrameParser
namespace frame_header {
// FrameHeader mRaw byte offsets.
static const int SYNC1 = 0;
static const int SYNC2_VERSION_LAYER_PROTECTION = 1;
static const int BITRATE_SAMPLERATE_PADDING_PRIVATE = 2;
static const int CHANNELMODE_MODEEXT_COPY_ORIG_EMPH = 3;
} // namespace frame_header
FrameParser::FrameParser()
{
}
void
FrameParser::Reset()
{
mID3Parser.Reset();
mFrame.Reset();
}
void
FrameParser::ResetFrameData()
{
mFrame.Reset();
mFirstFrame.Reset();
mPrevFrame.Reset();
}
void
FrameParser::EndFrameSession()
{
if (!mID3Parser.Header().IsValid()) {
// Reset ID3 tags only if we have not parsed a valid ID3 header yet.
mID3Parser.Reset();
}
mPrevFrame = mFrame;
mFrame.Reset();
}
const FrameParser::Frame&
FrameParser::CurrentFrame() const
{
return mFrame;
}
const FrameParser::Frame&
FrameParser::PrevFrame() const
{
return mPrevFrame;
}
const FrameParser::Frame&
FrameParser::FirstFrame() const
{
return mFirstFrame;
}
const ID3Parser::ID3Header&
FrameParser::ID3Header() const
{
return mID3Parser.Header();
}
const FrameParser::VBRHeader&
FrameParser::VBRInfo() const
{
return mVBRHeader;
}
bool
FrameParser::Parse(ByteReader* aReader, uint32_t* aBytesToSkip)
{
MOZ_ASSERT(aReader && aBytesToSkip);
*aBytesToSkip = 0;
if (!mID3Parser.Header().Size() && !mFirstFrame.Length()) {
// No MP3 frames have been parsed yet, look for ID3v2 headers at file begin.
// ID3v1 tags may only be at file end.
// TODO: should we try to read ID3 tags at end of file/mid-stream, too?
const size_t prevReaderOffset = aReader->Offset();
const uint32_t tagSize = mID3Parser.Parse(aReader);
if (tagSize) {
// ID3 tag found, skip past it.
const uint32_t skipSize = tagSize - ID3Parser::ID3Header::SIZE;
if (skipSize > aReader->Remaining()) {
// Skipping across the ID3v2 tag would take us past the end of the
// buffer, therefore we return immediately and let the calling function
// handle skipping the rest of the tag.
MP3LOGV("ID3v2 tag detected, size=%d,"
" needing to skip %" PRIuSIZE " bytes past the current buffer",
tagSize, skipSize - aReader->Remaining());
*aBytesToSkip = skipSize - aReader->Remaining();
return false;
}
MP3LOGV("ID3v2 tag detected, size=%d", tagSize);
aReader->Read(skipSize);
} else {
// No ID3v2 tag found, rewinding reader in order to search for a MPEG
// frame header.
aReader->Seek(prevReaderOffset);
}
}
while (aReader->CanRead8() && !mFrame.ParseNext(aReader->ReadU8())) { }
if (mFrame.Length()) {
// MP3 frame found.
if (!mFirstFrame.Length()) {
mFirstFrame = mFrame;
}
// Indicate success.
return true;
}
return false;
}
// FrameParser::Header
FrameParser::FrameHeader::FrameHeader()
{
Reset();
}
uint8_t
FrameParser::FrameHeader::Sync1() const
{
return mRaw[frame_header::SYNC1];
}
uint8_t
FrameParser::FrameHeader::Sync2() const
{
return 0x7 & mRaw[frame_header::SYNC2_VERSION_LAYER_PROTECTION] >> 5;
}
uint8_t
FrameParser::FrameHeader::RawVersion() const
{
return 0x3 & mRaw[frame_header::SYNC2_VERSION_LAYER_PROTECTION] >> 3;
}
uint8_t
FrameParser::FrameHeader::RawLayer() const
{
return 0x3 & mRaw[frame_header::SYNC2_VERSION_LAYER_PROTECTION] >> 1;
}
uint8_t
FrameParser::FrameHeader::RawProtection() const
{
return 0x1 & mRaw[frame_header::SYNC2_VERSION_LAYER_PROTECTION] >> 6;
}
uint8_t
FrameParser::FrameHeader::RawBitrate() const
{
return 0xF & mRaw[frame_header::BITRATE_SAMPLERATE_PADDING_PRIVATE] >> 4;
}
uint8_t
FrameParser::FrameHeader::RawSampleRate() const
{
return 0x3 & mRaw[frame_header::BITRATE_SAMPLERATE_PADDING_PRIVATE] >> 2;
}
uint8_t
FrameParser::FrameHeader::Padding() const
{
return 0x1 & mRaw[frame_header::BITRATE_SAMPLERATE_PADDING_PRIVATE] >> 1;
}
uint8_t
FrameParser::FrameHeader::Private() const
{
return 0x1 & mRaw[frame_header::BITRATE_SAMPLERATE_PADDING_PRIVATE];
}
uint8_t
FrameParser::FrameHeader::RawChannelMode() const
{
return 0x3 & mRaw[frame_header::CHANNELMODE_MODEEXT_COPY_ORIG_EMPH] >> 6;
}
int32_t
FrameParser::FrameHeader::Layer() const
{
static const uint8_t LAYERS[4] = { 0, 3, 2, 1 };
return LAYERS[RawLayer()];
}
int32_t
FrameParser::FrameHeader::SampleRate() const
{
// Sample rates - use [version][srate]
static const uint16_t SAMPLE_RATE[4][4] = {
{ 11025, 12000, 8000, 0 }, // MPEG 2.5
{ 0, 0, 0, 0 }, // Reserved
{ 22050, 24000, 16000, 0 }, // MPEG 2
{ 44100, 48000, 32000, 0 } // MPEG 1
};
return SAMPLE_RATE[RawVersion()][RawSampleRate()];
}
int32_t
FrameParser::FrameHeader::Channels() const
{
// 3 is single channel (mono), any other value is some variant of dual
// channel.
return RawChannelMode() == 3 ? 1 : 2;
}
int32_t
FrameParser::FrameHeader::SamplesPerFrame() const
{
// Samples per frame - use [version][layer]
static const uint16_t FRAME_SAMPLE[4][4] = {
// Layer 3 2 1 Version
{ 0, 576, 1152, 384 }, // 2.5
{ 0, 0, 0, 0 }, // Reserved
{ 0, 576, 1152, 384 }, // 2
{ 0, 1152, 1152, 384 } // 1
};
return FRAME_SAMPLE[RawVersion()][RawLayer()];
}
int32_t
FrameParser::FrameHeader::Bitrate() const
{
// Bitrates - use [version][layer][bitrate]
static const uint16_t BITRATE[4][4][16] = {
{ // Version 2.5
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 3
{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 2
{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 } // Layer 1
},
{ // Reserved
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } // Invalid
},
{ // Version 2
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 3
{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 2
{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 } // Layer 1
},
{ // Version 1
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
{ 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0 }, // Layer 3
{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0 }, // Layer 2