mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
synced 2024-09-13 09:24:08 -07:00
6510155080
This patch adds support for Xing and VBRI headers to MP3FrameParser so that we can calculate the exact duration of an MP3 file if these headers are present. It is also now more robust against large ID3 tags and discontinuities in input.
549 lines
16 KiB
C++
549 lines
16 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim:set ts=2 sw=2 sts=2 et cindent: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <algorithm>
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#include "nsMemory.h"
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#include "MP3FrameParser.h"
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#include "VideoUtils.h"
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#define FROM_BIG_ENDIAN(X) ((uint32_t)((uint8_t)(X)[0] << 24 | (uint8_t)(X)[1] << 16 | \
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(uint8_t)(X)[2] << 8 | (uint8_t)(X)[3]))
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namespace mozilla {
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/*
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* Following code taken from http://www.hydrogenaudio.org/forums/index.php?showtopic=85125
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* with permission from the author, Nick Wallette <sirnickity@gmail.com>.
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*/
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/* BEGIN shameless copy and paste */
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// Bitrates - use [version][layer][bitrate]
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const uint16_t mpeg_bitrates[4][4][16] = {
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{ // Version 2.5
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 3
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 2
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 } // Layer 1
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},
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{ // Reserved
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Invalid
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 } // Invalid
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},
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{ // Version 2
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 3
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{ 0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, 0 }, // Layer 2
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, 0 } // Layer 1
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},
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{ // Version 1
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{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, // Reserved
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{ 0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 0 }, // Layer 3
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{ 0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 0 }, // Layer 2
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{ 0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, 0 }, // Layer 1
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}
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};
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// Sample rates - use [version][srate]
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const uint16_t mpeg_srates[4][4] = {
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{ 11025, 12000, 8000, 0 }, // MPEG 2.5
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{ 0, 0, 0, 0 }, // Reserved
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{ 22050, 24000, 16000, 0 }, // MPEG 2
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{ 44100, 48000, 32000, 0 } // MPEG 1
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};
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// Samples per frame - use [version][layer]
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const uint16_t mpeg_frame_samples[4][4] = {
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// Rsvd 3 2 1 < Layer v Version
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{ 0, 576, 1152, 384 }, // 2.5
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{ 0, 0, 0, 0 }, // Reserved
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{ 0, 576, 1152, 384 }, // 2
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{ 0, 1152, 1152, 384 } // 1
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};
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// Slot size (MPEG unit of measurement) - use [layer]
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const uint8_t mpeg_slot_size[4] = { 0, 1, 1, 4 }; // Rsvd, 3, 2, 1
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uint16_t
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MP3Frame::CalculateLength()
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{
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// Lookup real values of these fields
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uint32_t bitrate = mpeg_bitrates[mVersion][mLayer][mBitrate] * 1000;
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uint32_t samprate = mpeg_srates[mVersion][mSampleRate];
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uint16_t samples = mpeg_frame_samples[mVersion][mLayer];
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uint8_t slot_size = mpeg_slot_size[mLayer];
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// In-between calculations
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float bps = (float)samples / 8.0;
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float fsize = ( (bps * (float)bitrate) / (float)samprate )
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+ ( (mPad) ? slot_size : 0 );
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// Frame sizes are truncated integers
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return (uint16_t)fsize;
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}
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/* END shameless copy and paste */
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/** MP3Parser methods **/
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MP3Parser::MP3Parser()
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: mCurrentChar(0)
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{ }
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void
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MP3Parser::Reset()
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{
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mCurrentChar = 0;
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}
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uint16_t
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MP3Parser::ParseFrameLength(uint8_t ch)
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{
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mData.mRaw[mCurrentChar] = ch;
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MP3Frame &frame = mData.mFrame;
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// Validate MP3 header as we read. We can't mistake the start of an MP3 frame
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// for the middle of another frame due to the sync byte at the beginning
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// of the frame.
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// The only valid position for an all-high byte is the sync byte at the
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// beginning of the frame.
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if (ch == 0xff) {
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mCurrentChar = 0;
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}
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// Make sure the current byte is valid in context. If not, reset the parser.
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if (mCurrentChar == 2) {
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if (frame.mBitrate == 0x0f) {
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goto fail;
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}
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} else if (mCurrentChar == 1) {
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if (frame.mSync2 != 0x07
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|| frame.mVersion == 0x01
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|| frame.mLayer == 0x00) {
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goto fail;
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}
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}
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// The only valid character at the beginning of the header is 0xff. Fail if
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// it's different.
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if (mCurrentChar == 0 && frame.mSync1 != 0xff) {
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// Couldn't find the sync byte. Fail.
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return 0;
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}
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mCurrentChar++;
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MOZ_ASSERT(mCurrentChar <= sizeof(MP3Frame));
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// Don't have a full header yet.
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if (mCurrentChar < sizeof(MP3Frame)) {
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return 0;
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}
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// Woo, valid header. Return the length.
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mCurrentChar = 0;
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return frame.CalculateLength();
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fail:
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Reset();
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return 0;
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}
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uint32_t
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MP3Parser::GetSampleRate()
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{
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MP3Frame &frame = mData.mFrame;
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return mpeg_srates[frame.mVersion][frame.mSampleRate];
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}
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uint32_t
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MP3Parser::GetSamplesPerFrame()
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{
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MP3Frame &frame = mData.mFrame;
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return mpeg_frame_samples[frame.mVersion][frame.mLayer];
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}
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/** ID3Parser methods **/
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const char sID3Head[3] = { 'I', 'D', '3' };
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const uint32_t ID3_HEADER_LENGTH = 10;
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ID3Parser::ID3Parser()
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: mCurrentChar(0)
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, mHeaderLength(0)
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{ }
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void
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ID3Parser::Reset()
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{
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mCurrentChar = mHeaderLength = 0;
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}
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bool
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ID3Parser::ParseChar(char ch)
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{
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// First three bytes of an ID3v2 header must match the string "ID3".
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if (mCurrentChar < sizeof(sID3Head) / sizeof(*sID3Head)
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&& ch != sID3Head[mCurrentChar]) {
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goto fail;
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}
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// The last four bytes of the header is a 28-bit unsigned integer with the
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// high bit of each byte unset.
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if (mCurrentChar >= 6 && mCurrentChar < ID3_HEADER_LENGTH) {
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if (ch & 0x80) {
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goto fail;
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} else {
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mHeaderLength <<= 7;
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mHeaderLength |= ch;
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}
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}
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mCurrentChar++;
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return IsParsed();
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fail:
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Reset();
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return false;
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}
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bool
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ID3Parser::IsParsed() const
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{
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return mCurrentChar >= ID3_HEADER_LENGTH;
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}
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uint32_t
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ID3Parser::GetHeaderLength() const
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{
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MOZ_ASSERT(IsParsed(),
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"Queried length of ID3 header before parsing finished.");
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return mHeaderLength;
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}
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/** VBR header helper stuff **/
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// Helper function to find a VBR header in an MP3 frame.
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// Based on information from
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// http://www.codeproject.com/Articles/8295/MPEG-Audio-Frame-Header
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const uint32_t VBRI_TAG = FROM_BIG_ENDIAN("VBRI");
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const uint32_t VBRI_OFFSET = 32 - sizeof(MP3Frame);
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const uint32_t VBRI_FRAME_COUNT_OFFSET = VBRI_OFFSET + 14;
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const uint32_t VBRI_MIN_FRAME_SIZE = VBRI_OFFSET + 26;
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const uint32_t XING_TAG = FROM_BIG_ENDIAN("Xing");
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enum XingFlags {
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XING_HAS_NUM_FRAMES = 0x01,
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XING_HAS_NUM_BYTES = 0x02,
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XING_HAS_TOC = 0x04,
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XING_HAS_VBR_SCALE = 0x08
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};
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static int64_t
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ParseXing(const char *aBuffer)
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{
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uint32_t flags = FROM_BIG_ENDIAN(aBuffer + 4);
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if (!(flags & XING_HAS_NUM_FRAMES)) {
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NS_WARNING("VBR file without frame count. Duration estimation likely to "
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"be totally wrong.");
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return -1;
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}
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int64_t numFrames = -1;
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if (flags & XING_HAS_NUM_FRAMES) {
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numFrames = FROM_BIG_ENDIAN(aBuffer + 8);
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}
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return numFrames;
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}
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static int64_t
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FindNumVBRFrames(const nsAutoCString& aFrame)
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{
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const char *buffer = aFrame.get();
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const char *bufferEnd = aFrame.get() + aFrame.Length();
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// VBRI header is nice and well-defined; let's try to find that first.
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if (aFrame.Length() > VBRI_MIN_FRAME_SIZE &&
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FROM_BIG_ENDIAN(buffer + VBRI_OFFSET) == VBRI_TAG) {
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return FROM_BIG_ENDIAN(buffer + VBRI_FRAME_COUNT_OFFSET);
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}
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// We have to search for the Xing header as its position can change.
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for (; buffer + sizeof(XING_TAG) < bufferEnd; buffer++) {
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if (FROM_BIG_ENDIAN(buffer) == XING_TAG) {
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return ParseXing(buffer);
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}
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}
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return -1;
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}
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/** MP3FrameParser methods **/
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// Some MP3's have large ID3v2 tags, up to 150KB, so we allow lots of
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// skipped bytes to be read, just in case, before we give up and assume
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// we're not parsing an MP3 stream.
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static const uint32_t MAX_SKIPPED_BYTES = 200 * 1024;
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// The number of audio samples per MP3 frame. This is constant over all MP3
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// streams. With this constant, the stream's sample rate, and an estimated
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// number of frames in the stream, we can estimate the stream's duration
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// fairly accurately.
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static const uint32_t SAMPLES_PER_FRAME = 1152;
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enum {
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MP3_HEADER_LENGTH = 4,
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};
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MP3FrameParser::MP3FrameParser(int64_t aLength)
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: mLock("MP3FrameParser.mLock"),
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mTotalID3Size(0),
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mTotalFrameSize(0),
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mFrameCount(0),
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mOffset(0),
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mLength(aLength),
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mMP3Offset(-1),
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mSamplesPerSecond(0),
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mFirstFrameEnd(-1),
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mIsMP3(MAYBE_MP3)
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{ }
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nsresult MP3FrameParser::ParseBuffer(const uint8_t* aBuffer,
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uint32_t aLength,
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int64_t aStreamOffset,
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uint32_t* aOutBytesRead)
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{
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// Iterate forwards over the buffer, looking for ID3 tag, or MP3
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// Frame headers.
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const uint8_t *buffer = aBuffer;
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const uint8_t *bufferEnd = aBuffer + aLength;
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// If we haven't found any MP3 frame data yet, there might be ID3 headers
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// we can skip over.
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if (mMP3Offset < 0) {
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for (const uint8_t *ch = buffer; ch < bufferEnd; ch++) {
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if (mID3Parser.ParseChar(*ch)) {
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// Found an ID3 header. We don't care about the body of the header, so
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// just skip past.
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buffer = ch + mID3Parser.GetHeaderLength() - (ID3_HEADER_LENGTH - 1);
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ch = buffer;
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mTotalID3Size += mID3Parser.GetHeaderLength();
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// Yes, this is an MP3!
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mIsMP3 = DEFINITELY_MP3;
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mID3Parser.Reset();
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}
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}
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}
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// The first MP3 frame in a variable bitrate stream can contain metadata
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// for duration estimation and seeking, so we buffer that first frame here.
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if (aStreamOffset < mFirstFrameEnd) {
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uint64_t copyLen = std::min((int64_t)aLength, mFirstFrameEnd - aStreamOffset);
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mFirstFrame.Append((const char *)buffer, copyLen);
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buffer += copyLen;
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}
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while (buffer < bufferEnd) {
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uint16_t frameLen = mMP3Parser.ParseFrameLength(*buffer);
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if (frameLen) {
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// We've found an MP3 frame!
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// This is the first frame (and the only one we'll bother parsing), so:
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// * Mark this stream as MP3;
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// * Store the offset at which the MP3 data started; and
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// * Start buffering the frame, as it might contain handy metadata.
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// We're now sure this is an MP3 stream.
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mIsMP3 = DEFINITELY_MP3;
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// We need to know these to convert the number of frames in the stream
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// to the length of the stream in seconds.
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mSamplesPerSecond = mMP3Parser.GetSampleRate();
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mSamplesPerFrame = mMP3Parser.GetSamplesPerFrame();
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// If the stream has a constant bitrate, we should only need the length
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// of the first frame and the length (in bytes) of the stream to
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// estimate the length (in seconds).
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mTotalFrameSize += frameLen;
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mFrameCount++;
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// If |mMP3Offset| isn't set then this is the first MP3 frame we have
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// seen in the stream, which is useful for duration estimation.
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if (mMP3Offset > -1) {
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uint16_t skip = frameLen - sizeof(MP3Frame);
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buffer += skip ? skip : 1;
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continue;
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}
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// Remember the offset of the MP3 stream.
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// We're at the last byte of an MP3Frame, so MP3 data started
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// sizeof(MP3Frame) - 1 bytes ago.
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mMP3Offset = aStreamOffset
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+ (buffer - aBuffer)
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- (sizeof(MP3Frame) - 1);
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buffer++;
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// If the stream has a variable bitrate, the first frame has metadata
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// we need for duration estimation and seeking. Start buffering it so we
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// can parse it later.
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mFirstFrameEnd = mMP3Offset + frameLen;
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uint64_t currOffset = buffer - aBuffer + aStreamOffset;
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uint64_t copyLen = std::min(mFirstFrameEnd - currOffset,
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(uint64_t)(bufferEnd - buffer));
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mFirstFrame.Append((const char *)buffer, copyLen);
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buffer += copyLen;
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} else {
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// Nothing to see here. Move along.
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buffer++;
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}
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}
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*aOutBytesRead = buffer - aBuffer;
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if (mFirstFrameEnd > -1 && mFirstFrameEnd <= aStreamOffset + buffer - aBuffer) {
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// We have our whole first frame. Try to find a VBR header.
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mNumFrames = FindNumVBRFrames(mFirstFrame);
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mFirstFrameEnd = -1;
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}
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return NS_OK;
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}
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void MP3FrameParser::Parse(const char* aBuffer, uint32_t aLength, uint64_t aOffset)
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{
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MutexAutoLock mon(mLock);
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if (HasExactDuration()) {
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// We know the duration; nothing to do here.
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return;
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}
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const uint8_t* buffer = reinterpret_cast<const uint8_t*>(aBuffer);
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int32_t length = aLength;
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uint64_t offset = aOffset;
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// Got some data we have seen already. Skip forward to what we need.
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if (aOffset < mOffset) {
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buffer += mOffset - aOffset;
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length -= mOffset - aOffset;
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offset = mOffset;
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if (length <= 0) {
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return;
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}
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}
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// If there is a discontinuity in the input stream, reset the state of the
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// parsers so we don't get any partial headers.
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if (mOffset < aOffset) {
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if (!mID3Parser.IsParsed()) {
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// Only reset this if it hasn't finished yet.
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mID3Parser.Reset();
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}
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if (mFirstFrameEnd > -1) {
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NS_WARNING("Discontinuity in input while buffering first frame.");
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mFirstFrameEnd = -1;
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}
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mMP3Parser.Reset();
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}
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uint32_t bytesRead = 0;
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if (NS_FAILED(ParseBuffer(buffer,
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length,
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offset,
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&bytesRead))) {
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return;
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}
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MOZ_ASSERT(length <= (int)bytesRead, "All bytes should have been consumed");
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// Update next data offset
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mOffset = offset + bytesRead;
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// If we've parsed lots of data and we still have nothing, just give up.
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// We don't count ID3 headers towards that count, as MP3 files can have
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// massive ID3 sections.
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if (!mID3Parser.IsParsed() && mMP3Offset < 0 &&
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mOffset - mTotalID3Size > MAX_SKIPPED_BYTES) {
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mIsMP3 = NOT_MP3;
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}
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}
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int64_t MP3FrameParser::GetDuration()
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{
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MutexAutoLock mon(mLock);
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|
if (mMP3Offset < 0) {
|
|
return -1; // Not a single frame decoded yet
|
|
}
|
|
|
|
double frames;
|
|
if (mNumFrames < 0) {
|
|
// Estimate the number of frames in the stream based on the average frame
|
|
// size and the length of the MP3 file.
|
|
double frameSize = (double)mTotalFrameSize / mFrameCount;
|
|
frames = (double)(mLength - mMP3Offset) / frameSize;
|
|
} else {
|
|
// We know the exact number of frames from the VBR header.
|
|
frames = mNumFrames;
|
|
}
|
|
|
|
// The duration of each frame is constant over a given stream.
|
|
double usPerFrame = USECS_PER_S * mSamplesPerFrame / mSamplesPerSecond;
|
|
|
|
return frames * usPerFrame;
|
|
}
|
|
|
|
int64_t MP3FrameParser::GetMP3Offset()
|
|
{
|
|
MutexAutoLock mon(mLock);
|
|
return mMP3Offset;
|
|
}
|
|
|
|
bool MP3FrameParser::ParsedHeaders()
|
|
{
|
|
// We have seen both the beginning and the end of the first MP3 frame in the
|
|
// stream.
|
|
return mMP3Offset > -1 && mFirstFrameEnd < 0;
|
|
}
|
|
|
|
bool MP3FrameParser::HasExactDuration()
|
|
{
|
|
return ParsedHeaders() && mNumFrames > -1;
|
|
}
|
|
|
|
bool MP3FrameParser::NeedsData()
|
|
{
|
|
// If we don't know the duration exactly then either:
|
|
// - we're still waiting for a VBR header; or
|
|
// - we look at all frames to constantly update our duration estimate.
|
|
return IsMP3() && !HasExactDuration();
|
|
}
|
|
|
|
}
|