gecko/dom/media/MP3Demuxer.h

465 lines
15 KiB
C++

/* 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/. */
#ifndef MP3_DEMUXER_H_
#define MP3_DEMUXER_H_
#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"
#include "MediaDataDemuxer.h"
#include "MediaResource.h"
#include "mp4_demuxer/ByteReader.h"
namespace mozilla {
namespace mp3 {
class MP3TrackDemuxer;
class MP3Demuxer : public MediaDataDemuxer {
public:
// MediaDataDemuxer interface.
explicit MP3Demuxer(MediaResource* aSource);
RefPtr<InitPromise> Init() override;
bool HasTrackType(TrackInfo::TrackType aType) const override;
uint32_t GetNumberTracks(TrackInfo::TrackType aType) const override;
already_AddRefed<MediaTrackDemuxer> GetTrackDemuxer(
TrackInfo::TrackType aType, uint32_t aTrackNumber) override;
bool IsSeekable() const override;
void NotifyDataArrived() override;
void NotifyDataRemoved() override;
// Do not shift the calculated buffered range by the start time of the first
// decoded frame. The mac MP3 decoder will buffer some samples and the first
// frame returned has typically a start time that is non-zero, causing our
// buffered range to have a negative start time.
bool ShouldComputeStartTime() const override { return false; }
private:
// Synchronous initialization.
bool InitInternal();
RefPtr<MediaResource> mSource;
RefPtr<MP3TrackDemuxer> mTrackDemuxer;
};
// ID3 header parser state machine used by FrameParser.
// The header contains the following format (one byte per term):
// 'I' 'D' '3' MajorVersion MinorVersion Flags Size1 Size2 Size3 Size4
// For more details see http://id3.org/id3v2.3.0.
class ID3Parser {
public:
// Holds the ID3 header and its parsing state.
class ID3Header {
public:
// The header size is static, see class comment.
static const int SIZE = 10;
// Constructor.
ID3Header();
// Resets the state to allow for a new parsing session.
void Reset();
// The ID3 tags are versioned like this: ID3vMajorVersion.MinorVersion.
uint8_t MajorVersion() const;
uint8_t MinorVersion() const;
// The ID3 flags field.
uint8_t Flags() const;
// The derived size based on the provided size fields.
uint32_t Size() const;
// Returns the size of an ID3v2.4 footer if present and zero otherwise.
uint8_t FooterSize() const;
// Returns whether the parsed data is a valid ID3 header up to the given
// byte position.
bool IsValid(int aPos) const;
// Returns whether the parsed data is a complete and valid ID3 header.
bool IsValid() const;
// Parses the next provided byte.
// Returns whether the byte creates a valid sequence up to this point.
bool ParseNext(uint8_t c);
private:
// Updates the parser state machine with the provided next byte.
// Returns whether the provided byte is a valid next byte in the sequence.
bool Update(uint8_t c);
// The currently parsed byte sequence.
uint8_t mRaw[SIZE];
// The derived size as provided by the size fields.
// The header size fields holds a 4 byte sequence with each MSB set to 0,
// this bits need to be ignored when deriving the actual size.
uint32_t mSize;
// The current byte position in the parsed sequence. Reset via Reset and
// incremented via Update.
int mPos;
};
// Returns the parsed ID3 header. Note: check for validity.
const ID3Header& Header() const;
// Parses contents of given ByteReader for a valid ID3v2 header.
// Returns the total ID3v2 tag size if successful and zero otherwise.
uint32_t Parse(mp4_demuxer::ByteReader* aReader);
// Resets the state to allow for a new parsing session.
void Reset();
private:
// The currently parsed ID3 header. Reset via Reset, updated via Parse.
ID3Header mHeader;
};
// MPEG audio frame parser.
// The MPEG frame header has the following format (one bit per character):
// 11111111 111VVLLC BBBBSSPR MMEETOHH
// { sync } - 11 sync bits
// VV - MPEG audio version ID (0->2.5, 1->reserved, 2->2, 3->1)
// LL - Layer description (0->reserved, 1->III, 2->II, 3->I)
// C - CRC protection bit (0->protected, 1->not protected)
// BBBB - Bitrate index (see table in implementation)
// SS - Sampling rate index (see table in implementation)
// P - Padding bit (0->not padded, 1->padded by 1 slot size)
// R - Private bit (ignored)
// MM - Channel mode (0->stereo, 1->joint stereo, 2->dual channel,
// 3->single channel)
// EE - Mode extension for joint stereo (ignored)
// T - Copyright (0->disabled, 1->enabled)
// O - Original (0->copy, 1->original)
// HH - Emphasis (0->none, 1->50/15 ms, 2->reserved, 3->CCIT J.17)
class FrameParser {
public:
// Holds the frame header and its parsing state.
class FrameHeader {
public:
// The header size is static, see class comments.
static const int SIZE = 4;
// Constructor.
FrameHeader();
// Raw field access, see class comments for details.
uint8_t Sync1() const;
uint8_t Sync2() const;
uint8_t RawVersion() const;
uint8_t RawLayer() const;
uint8_t RawProtection() const;
uint8_t RawBitrate() const;
uint8_t RawSampleRate() const;
uint8_t Padding() const;
uint8_t Private() const;
uint8_t RawChannelMode() const;
// Sampling rate frequency in Hz.
int32_t SampleRate() const;
// Number of audio channels.
int32_t Channels() const;
// Samples per frames, static depending on MPEG version and layer.
int32_t SamplesPerFrame() const;
// Slot size used for padding, static depending on MPEG layer.
int32_t SlotSize() const;
// Bitrate in kbps, can vary between frames.
int32_t Bitrate() const;
// MPEG layer (0->invalid, 1->I, 2->II, 3->III).
int32_t Layer() const;
// Returns whether the parsed data is a valid frame header up to the given
// byte position.
bool IsValid(const int aPos) const;
// Returns whether the parsed data is a complete and valid frame header.
bool IsValid() const;
// Resets the state to allow for a new parsing session.
void Reset();
// Parses the next provided byte.
// Returns whether the byte creates a valid sequence up to this point.
bool ParseNext(const uint8_t c);
private:
// Updates the parser state machine with the provided next byte.
// Returns whether the provided byte is a valid next byte in the sequence.
bool Update(const uint8_t c);
// The currently parsed byte sequence.
uint8_t mRaw[SIZE];
// The current byte position in the parsed sequence. Reset via Reset and
// incremented via Update.
int mPos;
};
// VBR frames may contain Xing or VBRI headers for additional info, we use
// this class to parse them and access this info.
class VBRHeader {
public:
// Synchronize with vbr_header TYPE_STR on change.
enum VBRHeaderType {
NONE = 0,
XING,
VBRI
};
// Constructor.
VBRHeader();
// Returns the parsed VBR header type, or NONE if no valid header found.
VBRHeaderType Type() const;
// Returns the total number of audio frames (excluding the VBR header frame)
// expected in the stream/file.
const Maybe<uint32_t>& NumAudioFrames() const;
// Returns the expected size of the stream.
const Maybe<uint32_t>& NumBytes() const;
// Returns the VBR scale factor (0: best quality, 100: lowest quality).
const Maybe<uint32_t>& Scale() const;
// Returns true iff Xing/Info TOC (table of contents) is present.
bool IsTOCPresent() const;
// Returns the byte offset for the given duration percentage as a factor
// (0: begin, 1.0: end).
int64_t Offset(float aDurationFac) const;
// Parses contents of given ByteReader for a valid VBR header.
// The offset of the passed ByteReader needs to point to an MPEG frame begin,
// as a VBRI-style header is searched at a fixed offset relative to frame begin.
// Returns whether a valid VBR header was found in the range.
bool Parse(mp4_demuxer::ByteReader* aReader);
private:
// Parses contents of given ByteReader for a valid Xing header.
// The initial ByteReader offset will be preserved.
// Returns whether a valid Xing header was found in the range.
bool ParseXing(mp4_demuxer::ByteReader* aReader);
// Parses contents of given ByteReader for a valid VBRI header.
// The initial ByteReader offset will be preserved. It also needs to point
// to the beginning of a valid MPEG frame, as VBRI headers are searched
// at a fixed offset relative to frame begin.
// Returns whether a valid VBRI header was found in the range.
bool ParseVBRI(mp4_demuxer::ByteReader* aReader);
// The total number of frames expected as parsed from a VBR header.
Maybe<uint32_t> mNumAudioFrames;
// The total number of bytes expected in the stream.
Maybe<uint32_t> mNumBytes;
// The VBR scale factor.
Maybe<uint32_t> mScale;
// The TOC table mapping duration percentage to byte offset.
std::vector<int64_t> mTOC;
// The detected VBR header type.
VBRHeaderType mType;
};
// Frame meta container used to parse and hold a frame header and side info.
class Frame {
public:
// Returns the length of the frame excluding the header in bytes.
int32_t Length() const;
// Returns the parsed frame header.
const FrameHeader& Header() const;
// Resets the frame header and data.
void Reset();
// Parses the next provided byte.
// Returns whether the byte creates a valid sequence up to this point.
bool ParseNext(uint8_t c);
private:
// The currently parsed frame header.
FrameHeader mHeader;
};
// Constructor.
FrameParser();
// Returns the currently parsed frame. Reset via Reset or EndFrameSession.
const Frame& CurrentFrame() const;
#ifdef ENABLE_TESTS
// Returns the previously parsed frame. Reset via Reset.
const Frame& PrevFrame() const;
#endif
// Returns the first parsed frame. Reset via Reset.
const Frame& FirstFrame() const;
// Returns the parsed ID3 header. Note: check for validity.
const ID3Parser::ID3Header& ID3Header() const;
// Returns the parsed VBR header info. Note: check for validity by type.
const VBRHeader& VBRInfo() const;
// Resets the parser. Don't use between frames as first frame data is reset.
void Reset();
// Clear the last parsed frame to allow for next frame parsing, i.e.:
// - sets PrevFrame to CurrentFrame
// - resets the CurrentFrame
// - resets ID3Header if no valid header was parsed yet
void EndFrameSession();
// Parses contents of given ByteReader for a valid frame header and returns true
// if one was found. After returning, the variable passed to 'aBytesToSkip' holds
// the amount of bytes to be skipped (if any) in order to jump across a large
// ID3v2 tag spanning multiple buffers.
bool Parse(mp4_demuxer::ByteReader* aReader, uint32_t* aBytesToSkip);
// Parses contents of given ByteReader for a valid VBR header.
// The offset of the passed ByteReader needs to point to an MPEG frame begin,
// as a VBRI-style header is searched at a fixed offset relative to frame begin.
// Returns whether a valid VBR header was found.
bool ParseVBRHeader(mp4_demuxer::ByteReader* aReader);
private:
// ID3 header parser.
ID3Parser mID3Parser;
// VBR header parser.
VBRHeader mVBRHeader;
// We keep the first parsed frame around for static info access, the
// previously parsed frame for debugging and the currently parsed frame.
Frame mFirstFrame;
Frame mFrame;
#ifdef ENABLE_TESTS
Frame mPrevFrame;
#endif
};
// The MP3 demuxer used to extract MPEG frames and side information out of
// MPEG streams.
class MP3TrackDemuxer : public MediaTrackDemuxer {
public:
// Constructor, expecting a valid media resource.
explicit MP3TrackDemuxer(MediaResource* aSource);
// Initializes the track demuxer by reading the first frame for meta data.
// Returns initialization success state.
bool Init();
// Returns the total stream length if known, -1 otherwise.
int64_t StreamLength() const;
// Returns the estimated stream duration, or a 0-duration if unknown.
media::TimeUnit Duration() const;
// Returns the estimated duration up to the given frame number,
// or a 0-duration if unknown.
media::TimeUnit Duration(int64_t aNumFrames) const;
#ifdef ENABLE_TESTS
const FrameParser::Frame& LastFrame() const;
RefPtr<MediaRawData> DemuxSample();
media::TimeUnit SeekPosition() const;
#endif
const ID3Parser::ID3Header& ID3Header() const;
const FrameParser::VBRHeader& VBRInfo() const;
// MediaTrackDemuxer interface.
UniquePtr<TrackInfo> GetInfo() const override;
RefPtr<SeekPromise> Seek(media::TimeUnit aTime) override;
RefPtr<SamplesPromise> GetSamples(int32_t aNumSamples = 1) override;
void Reset() override;
RefPtr<SkipAccessPointPromise> SkipToNextRandomAccessPoint(
media::TimeUnit aTimeThreshold) override;
int64_t GetResourceOffset() const override;
media::TimeIntervals GetBuffered() override;
private:
// Destructor.
~MP3TrackDemuxer() {}
// Fast approximate seeking to given time.
media::TimeUnit FastSeek(const media::TimeUnit& aTime);
// Seeks by scanning the stream up to the given time for more accurate results.
media::TimeUnit ScanUntil(const media::TimeUnit& aTime);
// Finds the next valid frame and returns its byte range.
MediaByteRange FindNextFrame();
// Skips the next frame given the provided byte range.
bool SkipNextFrame(const MediaByteRange& aRange);
// Returns the next MPEG frame, if available.
already_AddRefed<MediaRawData> GetNextFrame(const MediaByteRange& aRange);
// Updates post-read meta data.
void UpdateState(const MediaByteRange& aRange);
// Returns the frame index for the given offset.
int64_t FrameIndexFromOffset(int64_t aOffset) const;
// Returns the frame index for the given time.
int64_t FrameIndexFromTime(const media::TimeUnit& aTime) const;
// Reads aSize bytes into aBuffer from the source starting at aOffset.
// Returns the actual size read.
int32_t Read(uint8_t* aBuffer, int64_t aOffset, int32_t aSize);
// Returns the average frame length derived from the previously parsed frames.
double AverageFrameLength() const;
// The (hopefully) MPEG resource.
MediaResourceIndex mSource;
// MPEG frame parser used to detect frames and extract side info.
FrameParser mParser;
// Current byte offset in the source stream.
int64_t mOffset;
// Byte offset of the begin of the first frame, or 0 if none parsed yet.
int64_t mFirstFrameOffset;
// Total parsed frames.
uint64_t mNumParsedFrames;
// Current frame index.
int64_t mFrameIndex;
// Sum of parsed frames' lengths in bytes.
uint64_t mTotalFrameLen;
// Samples per frame metric derived from frame headers or 0 if none available.
int32_t mSamplesPerFrame;
// Samples per second metric derived from frame headers or 0 if none available.
int32_t mSamplesPerSecond;
// Channel count derived from frame headers or 0 if none available.
int32_t mChannels;
// Audio track config info.
UniquePtr<AudioInfo> mInfo;
};
} // namespace mp3
} // namespace mozilla
#endif