tor-browser

MP3Demuxer.h (6083B)

---

/* 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 "MP3FrameParser.h"
#include "MediaDataDemuxer.h"
#include "MediaResource.h"

namespace mozilla {

class MP3TrackDemuxer;

DDLoggedTypeDeclNameAndBase(MP3Demuxer, MediaDataDemuxer);
DDLoggedTypeNameAndBase(MP3TrackDemuxer, MediaTrackDemuxer);

class MP3Demuxer : public MediaDataDemuxer,
                  public DecoderDoctorLifeLogger<MP3Demuxer> {
public:
 // MediaDataDemuxer interface.
 explicit MP3Demuxer(MediaResource* aSource);
 RefPtr<InitPromise> Init() 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;
};

// The MP3 demuxer used to extract MPEG frames and side information out of
// MPEG streams.
class MP3TrackDemuxer : public MediaTrackDemuxer,
                       public DecoderDoctorLifeLogger<MP3TrackDemuxer> {
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::NullableTimeUnit 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(const media::TimeUnit& aTime) override;
 RefPtr<SamplesPromise> GetSamples(int32_t aNumSamples = 1) override;
 void Reset() override;
 RefPtr<SkipAccessPointPromise> SkipToNextRandomAccessPoint(
     const media::TimeUnit& aTimeThreshold) override;
 int64_t GetResourceOffset() const override;
 media::TimeIntervals GetBuffered() override;
 // Return the duration in frames of the encoder delay.
 uint32_t EncoderDelayFrames() const;
 // Return the duration  in frames of the padding.
 uint32_t PaddingFrames() const;

private:
 // Destructor.
 ~MP3TrackDemuxer() = default;

 // 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.
 uint32_t Read(uint8_t* aBuffer, int64_t aOffset, uint32_t aSize);

 // Returns the average frame length derived from the previously parsed frames.
 double AverageFrameLength() const;

 // Returns the number of frames reported by the header if it's valid. Nothing
 // otherwise.
 Maybe<uint32_t> ValidNumAudioFrames() const;

 // Return the duration of the encoder delay.
 media::TimeUnit EncoderDelay() const;

 // Return the duration of the padding.
 media::TimeUnit Padding() const;

 // The (hopefully) MPEG resource.
 MediaResourceIndex mSource;

 // MPEG frame parser used to detect frames and extract side info.
 FrameParser mParser;

 // Whether we've locked onto a valid sequence of frames or not.
 bool mFrameLock;

 // 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.
 int64_t mTotalFrameLen;

 // Samples per frame metric derived from frame headers or 0 if none available.
 uint32_t mSamplesPerFrame;

 // Samples per second metric derived from frame headers or 0 if none
 // available.
 uint32_t mSamplesPerSecond;

 // Channel count derived from frame headers or 0 if none available.
 uint32_t mChannels;

 // Audio track config info.
 UniquePtr<AudioInfo> mInfo;

 // Number of frames to skip at the beginning
 uint32_t mEncoderDelay = 0;
 // Number of frames to skip at the end
 uint32_t mEncoderPadding = 0;
 int32_t mRemainingEncoderPadding = 0;
 // End of stream has been found
 bool mEOS = false;
};

}  // namespace mozilla

#endif