mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
synced 2024-09-13 09:24:08 -07:00
267 lines
8.4 KiB
C++
267 lines
8.4 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 "nsAlgorithm.h"
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#include "WebMBufferedParser.h"
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#include "mozilla/dom/TimeRanges.h"
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#include "nsThreadUtils.h"
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#include <algorithm>
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namespace mozilla {
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static uint32_t
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VIntLength(unsigned char aFirstByte, uint32_t* aMask)
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{
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uint32_t count = 1;
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uint32_t mask = 1 << 7;
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while (count < 8) {
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if ((aFirstByte & mask) != 0) {
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break;
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}
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mask >>= 1;
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count += 1;
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}
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if (aMask) {
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*aMask = mask;
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}
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NS_ASSERTION(count >= 1 && count <= 8, "Insane VInt length.");
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return count;
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}
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void WebMBufferedParser::Append(const unsigned char* aBuffer, uint32_t aLength,
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nsTArray<WebMTimeDataOffset>& aMapping,
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ReentrantMonitor& aReentrantMonitor)
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{
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static const unsigned char CLUSTER_ID[] = { 0x1f, 0x43, 0xb6, 0x75 };
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static const unsigned char TIMECODE_ID = 0xe7;
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static const unsigned char BLOCKGROUP_ID = 0xa0;
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static const unsigned char BLOCK_ID = 0xa1;
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static const unsigned char SIMPLEBLOCK_ID = 0xa3;
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const unsigned char* p = aBuffer;
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// Parse each byte in aBuffer one-by-one, producing timecodes and updating
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// aMapping as we go. Parser pauses at end of stream (which may be at any
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// point within the parse) and resumes parsing the next time Append is
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// called with new data.
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while (p < aBuffer + aLength) {
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switch (mState) {
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case CLUSTER_SYNC:
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if (*p++ == CLUSTER_ID[mClusterIDPos]) {
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mClusterIDPos += 1;
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} else {
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mClusterIDPos = 0;
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}
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// Cluster ID found, it's likely this is a valid sync point. If this
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// is a spurious match, the later parse steps will encounter an error
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// and return to CLUSTER_SYNC.
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if (mClusterIDPos == sizeof(CLUSTER_ID)) {
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mClusterIDPos = 0;
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mState = READ_VINT;
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mNextState = TIMECODE_SYNC;
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}
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break;
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case READ_VINT: {
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unsigned char c = *p++;
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uint32_t mask;
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mVIntLength = VIntLength(c, &mask);
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mVIntLeft = mVIntLength - 1;
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mVInt = c & ~mask;
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mState = READ_VINT_REST;
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break;
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}
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case READ_VINT_REST:
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if (mVIntLeft) {
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mVInt <<= 8;
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mVInt |= *p++;
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mVIntLeft -= 1;
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} else {
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mState = mNextState;
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}
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break;
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case TIMECODE_SYNC:
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if (*p++ != TIMECODE_ID) {
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p -= 1;
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mState = CLUSTER_SYNC;
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break;
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}
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mClusterTimecode = 0;
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mState = READ_VINT;
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mNextState = READ_CLUSTER_TIMECODE;
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break;
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case READ_CLUSTER_TIMECODE:
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if (mVInt) {
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mClusterTimecode <<= 8;
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mClusterTimecode |= *p++;
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mVInt -= 1;
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} else {
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mState = ANY_BLOCK_SYNC;
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}
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break;
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case ANY_BLOCK_SYNC: {
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unsigned char c = *p++;
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if (c == BLOCKGROUP_ID) {
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mState = READ_VINT;
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mNextState = ANY_BLOCK_SYNC;
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} else if (c == SIMPLEBLOCK_ID || c == BLOCK_ID) {
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mBlockOffset = mCurrentOffset + (p - aBuffer) - 1;
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mState = READ_VINT;
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mNextState = READ_BLOCK;
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} else {
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uint32_t length = VIntLength(c, nullptr);
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if (length == 4) {
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p -= 1;
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mState = CLUSTER_SYNC;
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} else {
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mState = READ_VINT;
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mNextState = SKIP_ELEMENT;
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}
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}
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break;
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}
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case READ_BLOCK:
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mBlockSize = mVInt;
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mBlockTimecode = 0;
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mBlockTimecodeLength = 2;
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mState = READ_VINT;
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mNextState = READ_BLOCK_TIMECODE;
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break;
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case READ_BLOCK_TIMECODE:
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if (mBlockTimecodeLength) {
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mBlockTimecode <<= 8;
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mBlockTimecode |= *p++;
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mBlockTimecodeLength -= 1;
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} else {
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// It's possible we've parsed this data before, so avoid inserting
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// duplicate WebMTimeDataOffset entries.
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{
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ReentrantMonitorAutoEnter mon(aReentrantMonitor);
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uint32_t idx = aMapping.IndexOfFirstElementGt(mBlockOffset);
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if (idx == 0 || !(aMapping[idx-1] == mBlockOffset)) {
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WebMTimeDataOffset entry(mBlockOffset, mClusterTimecode + mBlockTimecode);
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aMapping.InsertElementAt(idx, entry);
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}
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}
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// Skip rest of block header and the block's payload.
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mBlockSize -= mVIntLength;
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mBlockSize -= 2;
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mSkipBytes = uint32_t(mBlockSize);
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mState = SKIP_DATA;
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mNextState = ANY_BLOCK_SYNC;
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}
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break;
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case SKIP_DATA:
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if (mSkipBytes) {
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uint32_t left = aLength - (p - aBuffer);
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left = std::min(left, mSkipBytes);
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p += left;
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mSkipBytes -= left;
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} else {
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mState = mNextState;
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}
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break;
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case SKIP_ELEMENT:
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mSkipBytes = uint32_t(mVInt);
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mState = SKIP_DATA;
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mNextState = ANY_BLOCK_SYNC;
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break;
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}
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}
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NS_ASSERTION(p == aBuffer + aLength, "Must have parsed to end of data.");
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mCurrentOffset += aLength;
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}
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bool WebMBufferedState::CalculateBufferedForRange(int64_t aStartOffset, int64_t aEndOffset,
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uint64_t* aStartTime, uint64_t* aEndTime)
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{
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ReentrantMonitorAutoEnter mon(mReentrantMonitor);
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// Find the first WebMTimeDataOffset at or after aStartOffset.
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uint32_t start = mTimeMapping.IndexOfFirstElementGt(aStartOffset-1);
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if (start == mTimeMapping.Length()) {
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return false;
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}
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// Find the first WebMTimeDataOffset at or before aEndOffset.
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uint32_t end = mTimeMapping.IndexOfFirstElementGt(aEndOffset-1);
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if (end > 0) {
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end -= 1;
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}
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// Range is empty.
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if (end <= start) {
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return false;
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}
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NS_ASSERTION(mTimeMapping[start].mOffset >= aStartOffset &&
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mTimeMapping[end].mOffset <= aEndOffset,
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"Computed time range must lie within data range.");
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if (start > 0) {
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NS_ASSERTION(mTimeMapping[start - 1].mOffset <= aStartOffset,
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"Must have found least WebMTimeDataOffset for start");
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}
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if (end < mTimeMapping.Length() - 1) {
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NS_ASSERTION(mTimeMapping[end + 1].mOffset >= aEndOffset,
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"Must have found greatest WebMTimeDataOffset for end");
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}
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// The timestamp of the first media sample, in ns. We must subtract this
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// from the ranges' start and end timestamps, so that those timestamps are
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// normalized in the range [0,duration].
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*aStartTime = mTimeMapping[start].mTimecode;
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*aEndTime = mTimeMapping[end].mTimecode;
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return true;
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}
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void WebMBufferedState::NotifyDataArrived(const char* aBuffer, uint32_t aLength, int64_t aOffset)
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{
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NS_ASSERTION(NS_IsMainThread(), "Should be on main thread.");
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uint32_t idx = mRangeParsers.IndexOfFirstElementGt(aOffset - 1);
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if (idx == 0 || !(mRangeParsers[idx-1] == aOffset)) {
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// If the incoming data overlaps an already parsed range, adjust the
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// buffer so that we only reparse the new data. It's also possible to
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// have an overlap where the end of the incoming data is within an
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// already parsed range, but we don't bother handling that other than by
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// avoiding storing duplicate timecodes when the parser runs.
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if (idx != mRangeParsers.Length() && mRangeParsers[idx].mStartOffset <= aOffset) {
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// Complete overlap, skip parsing.
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if (aOffset + aLength <= mRangeParsers[idx].mCurrentOffset) {
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return;
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}
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// Partial overlap, adjust the buffer to parse only the new data.
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int64_t adjust = mRangeParsers[idx].mCurrentOffset - aOffset;
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NS_ASSERTION(adjust >= 0, "Overlap detection bug.");
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aBuffer += adjust;
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aLength -= uint32_t(adjust);
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} else {
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mRangeParsers.InsertElementAt(idx, WebMBufferedParser(aOffset));
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}
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}
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mRangeParsers[idx].Append(reinterpret_cast<const unsigned char*>(aBuffer),
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aLength,
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mTimeMapping,
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mReentrantMonitor);
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// Merge parsers with overlapping regions and clean up the remnants.
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uint32_t i = 0;
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while (i + 1 < mRangeParsers.Length()) {
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if (mRangeParsers[i].mCurrentOffset >= mRangeParsers[i + 1].mStartOffset) {
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mRangeParsers[i + 1].mStartOffset = mRangeParsers[i].mStartOffset;
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mRangeParsers.RemoveElementAt(i);
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} else {
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i += 1;
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}
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}
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}
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} // namespace mozilla
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