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-rw-r--r--dom/media/MP3FrameParser.h219
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diff --git a/dom/media/MP3FrameParser.h b/dom/media/MP3FrameParser.h
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--- a/dom/media/MP3FrameParser.h
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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/. */
-
-#ifndef MP3FrameParser_h
-#define MP3FrameParser_h
-
-#include <stdint.h>
-
-#include "mozilla/Mutex.h"
-#include "nsString.h"
-#include "Intervals.h"
-
-namespace mozilla {
-
-// Simple parser to tell whether we've found an ID3 header and how long it is,
-// so that we can skip it.
-// XXX maybe actually parse this stuff?
-class ID3Parser
-{
-public:
- ID3Parser();
-
- void Reset();
- bool ParseChar(char ch);
- bool IsParsed() const;
- uint32_t GetHeaderLength() const;
-
-private:
- uint32_t mCurrentChar;
- uint8_t mVersion;
- uint8_t mFlags;
- uint32_t mHeaderLength;
-};
-
-struct MP3Frame {
- uint16_t mSync1 : 8; // Always all set
- uint16_t mProtected : 1; // Ignored
- uint16_t mLayer : 2;
- uint16_t mVersion : 2;
- uint16_t mSync2 : 3; // Always all set
- uint16_t mPrivate : 1; // Ignored
- uint16_t mPad : 1;
- uint16_t mSampleRate : 2; // Index into mpeg_srates above
- uint16_t mBitrate : 4; // Index into mpeg_bitrates above
-
- uint16_t CalculateLength();
-};
-
-// Buffering parser for MP3 frames.
-class MP3Parser
-{
-public:
- MP3Parser();
-
- // Forget all data the parser has seen so far.
- void Reset();
-
- // Parse the given byte. If we have found a frame header, return the length of
- // the frame.
- uint16_t ParseFrameLength(uint8_t ch);
-
- // Get the sample rate from the current header.
- uint32_t GetSampleRate();
-
- // Get the number of samples per frame.
- uint32_t GetSamplesPerFrame();
-
-private:
- uint32_t mCurrentChar;
- union {
- uint8_t mRaw[3];
- MP3Frame mFrame;
- } mData;
-};
-
-
-// A description of the MP3 format and its extensions is available at
-//
-// http://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header
-//
-// The data in MP3 streams is split into small frames, with each frame
-// containing a fixed number of samples. The duration of a frame depends
-// on the frame's bit rate and sample rate. Both values can vary among
-// frames, so it is necessary to examine each individual frame of an MP3
-// stream to calculate the stream's overall duration.
-//
-// The MP3 frame parser extracts information from an MP3 data stream. It
-// accepts a range of frames of an MP3 stream as input, and parses all
-// frames for their duration. Callers can query the stream's overall
-// duration from the parser.
-//
-// Call the methods NotifyDataArrived or Parse to add new data. If you added
-// information for a certain stream position, you cannot go back to previous
-// positions. The parser will simply ignore the input. If you skip stream
-// positions, the duration of the related MP3 frames will be estimated from
-// the stream's average.
-//
-// The method GetDuration returns calculated duration of the stream, including
-// estimates for skipped ranges.
-//
-// All public methods are thread-safe.
-
-class MP3FrameParser
-{
-public:
- explicit MP3FrameParser(int64_t aLength=-1);
-
- bool IsMP3() {
- MutexAutoLock mon(mLock);
- return mIsMP3 != NOT_MP3;
- }
-
- void Parse(const uint8_t* aBuffer, uint32_t aLength, uint64_t aStreamOffset);
-
- // Returns the duration, in microseconds. If the entire stream has not
- // been parsed yet, this is an estimate based on the bitrate of the
- // frames parsed so far.
- int64_t GetDuration();
-
- // Returns the offset of the first MP3 frame in the stream, or -1 of
- // no MP3 frame has been detected yet.
- int64_t GetMP3Offset();
-
- // Returns true if we've seen the whole first frame of the MP3 stream, and
- // therefore can make an estimate on the stream duration.
- // Otherwise, returns false.
- bool ParsedHeaders();
-
- // Returns true if we know the exact duration of the MP3 stream;
- // false otherwise.
- bool HasExactDuration();
-
- // Returns true if the parser needs more data for duration estimation.
- bool NeedsData();
- // Assign the total lenght of this mp3 stream
- void SetLength(int64_t aLength) {
- MutexAutoLock mon(mLock);
- mLength = aLength;
- }
-private:
-
- // Parses aBuffer, starting at offset 0. Returns the number of bytes
- // parsed, relative to the start of the buffer. Note this may be
- // greater than aLength if the headers in the buffer indicate that
- // the frame or ID3 tag extends outside of aBuffer. Returns failure
- // if too many non-MP3 bytes are parsed.
- nsresult ParseBuffer(const uint8_t* aBuffer,
- uint32_t aLength,
- int64_t aStreamOffset,
- uint32_t* aOutBytesRead);
-
- // A low-contention lock for protecting the parser results
- Mutex mLock;
-
- // ID3 header parser. Keeps state between reads in case the header falls
- // in between.
- ID3Parser mID3Parser;
-
- // MP3 frame header parser.
- MP3Parser mMP3Parser;
-
- // If we read |MAX_SKIPPED_BYTES| from the stream without finding any MP3
- // frames, we give up and report |NOT_MP3|. Here we track the cumulative size
- // of any ID3 headers we've seen so big ID3 sections aren't counted towards
- // skipped bytes.
- uint32_t mTotalID3Size;
-
- // All fields below are protected by mLock
-
- // We keep stats on the size of all the frames we've seen, as well as how many
- // so that we can estimate the duration of the rest of the stream.
- uint64_t mTotalFrameSize;
- uint64_t mFrameCount;
-
- // Offset of the last data parsed. This is the end offset of the last data
- // block parsed, so it's the start offset we expect to get on the next
- // call to Parse().
- uint64_t mOffset;
-
- // Total length of the stream in bytes.
- int64_t mLength;
-
- // Offset of first MP3 frame in the bitstream. Has value -1 until the
- // first MP3 frame is found.
- int64_t mMP3Offset;
-
- // The exact number of frames in this stream, if we know it. -1 otherwise.
- int64_t mNumFrames;
-
- // Number of audio samples per second and per frame. Fixed through the whole
- // file. If we know these variables as well as the number of frames in the
- // file, we can get an exact duration for the stream.
- uint16_t mSamplesPerSecond;
- uint16_t mSamplesPerFrame;
-
- // If the MP3 has a variable bitrate, then there *should* be metadata about
- // the encoding in the first frame. We buffer the first frame here.
- nsCString mFirstFrame;
-
- // While we are reading the first frame, this is the stream offset of the
- // last byte of that frame. -1 at all other times.
- int64_t mFirstFrameEnd;
-
- enum eIsMP3 {
- MAYBE_MP3, // We're giving the stream the benefit of the doubt...
- DEFINITELY_MP3, // We've hit at least one ID3 tag or MP3 frame.
- NOT_MP3 // Not found any evidence of the stream being MP3.
- };
-
- eIsMP3 mIsMP3;
-
-};
-
-} // namespace mozilla
-
-#endif