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Diffstat (limited to 'dom/media/MP3FrameParser.h')
-rw-r--r-- | dom/media/MP3FrameParser.h | 219 |
1 files changed, 0 insertions, 219 deletions
diff --git a/dom/media/MP3FrameParser.h b/dom/media/MP3FrameParser.h deleted file mode 100644 index d2ba791fd..000000000 --- a/dom/media/MP3FrameParser.h +++ /dev/null @@ -1,219 +0,0 @@ -/* -*- 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 |