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+/* 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"
+#include <vector>
+
+namespace mozilla {
+
+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;
+
+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 whether the header is valid (type XING or VBRI).
+ bool IsValid() const;
+
+ // Returns whether the header is valid and contains reasonable non-zero field values.
+ bool IsComplete() 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;
+
+ // Returns the previously parsed frame. Reset via Reset.
+ const Frame& PrevFrame() const;
+
+ // 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.
+ void Reset();
+
+ // Resets all frame data, but not the ID3Header.
+ // Don't use between frames as first frame data is reset.
+ void ResetFrameData();
+
+ // 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;
+ Frame mPrevFrame;
+};
+
+// 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;
+
+ // Returns the estimated current seek position time.
+ media::TimeUnit SeekPosition() const;
+
+ const FrameParser::Frame& LastFrame() const;
+ RefPtr<MediaRawData> DemuxSample();
+
+ 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 first valid frame and returns its byte range if found
+ // or a null-byte range otherwise.
+ MediaByteRange FindFirstFrame();
+
+ // Finds the next valid frame and returns its byte range if found
+ // or a null-byte range otherwise.
+ 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 estimated offset for the given frame index.
+ int64_t OffsetFromFrameIndex(int64_t aFrameIndex) const;
+
+ // Returns the estimated frame index for the given offset.
+ int64_t FrameIndexFromOffset(int64_t aOffset) const;
+
+ // Returns the estimated 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 mozilla
+
+#endif