207 lines
6.5 KiB
C++
207 lines
6.5 KiB
C++
/*
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* Copyright (C) 2020 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include "SFrameUtils.h"
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#if ENABLE(WEB_RTC)
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#include <wtf/Function.h>
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namespace WebCore {
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static inline bool isSliceNALU(uint8_t data)
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{
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return (data & 0x1F) == 1;
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}
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static inline bool isSPSNALU(uint8_t data)
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{
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return (data & 0x1F) == 7;
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}
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static inline bool isPPSNALU(uint8_t data)
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{
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return (data & 0x1F) == 8;
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}
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static inline bool isIDRNALU(uint8_t data)
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{
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return (data & 0x1F) == 5;
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}
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static inline void findNalus(const uint8_t* frameData, size_t frameSize, size_t offset, const Function<bool(size_t)>& callback)
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{
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for (size_t i = 4 + offset; i < frameSize; ++i) {
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if (frameData[i - 4] == 0 && frameData[i - 3] == 0 && frameData[i - 2] == 0 && frameData[i - 1] == 1) {
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if (callback(i))
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return;
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}
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}
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}
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size_t computeH264PrefixOffset(const uint8_t* frameData, size_t frameSize)
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{
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size_t offset = 0;
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findNalus(frameData, frameSize, 0, [&offset, &frameData](auto position) {
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if (isIDRNALU(frameData[position]) || isSliceNALU(frameData[position])) {
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// Skip 00 00 00 01, nalu type byte and the next byte.
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offset = position + 2;
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return true;
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}
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return false;
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});
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return offset;
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}
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bool needsRbspUnescaping(const uint8_t* frameData, size_t frameSize)
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{
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for (size_t i = 0; i < frameSize - 3; ++i) {
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if (frameData[i] == 0 && frameData[i + 1] == 0 && frameData[i + 2] == 3)
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return true;
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}
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return false;
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}
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Vector<uint8_t> fromRbsp(const uint8_t* frameData, size_t frameSize)
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{
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Vector<uint8_t> buffer;
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buffer.reserveInitialCapacity(frameSize);
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size_t i;
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for (i = 0; i < frameSize - 3; ++i) {
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if (frameData[i] == 0 && frameData[i + 1] == 0 && frameData[i + 2] == 3) {
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buffer.uncheckedAppend(frameData[i]);
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buffer.uncheckedAppend(frameData[i + 1]);
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// Skip next byte which is delimiter.
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i += 2;
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} else
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buffer.uncheckedAppend(frameData[i]);
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}
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for (; i < frameSize; ++i)
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buffer.uncheckedAppend(frameData[i]);
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return buffer;
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}
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SFrameCompatibilityPrefixBuffer computeH264PrefixBuffer(const uint8_t* frameData, size_t frameSize)
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{
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// Delta and key prefixes assume SPS/PPS with IDs equal to 0 have been transmitted.
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static const uint8_t prefixDeltaFrame[6] = { 0x00, 0x00, 0x00, 0x01, 0x21, 0xe0 };
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if (frameSize < 5)
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return { };
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// We assume a key frame starts with SPS, then PPS. Otherwise we wrap it as a delta frame.
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if (!isSPSNALU(frameData[4]))
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return SFrameCompatibilityPrefixBuffer { prefixDeltaFrame, sizeof(prefixDeltaFrame), { } };
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// Search for PPS
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size_t spsPpsLength = 0;
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findNalus(frameData, frameSize, 5, [frameData, &spsPpsLength](auto position) {
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if (isPPSNALU(frameData[position]))
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spsPpsLength = position;
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return true;
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});
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if (!spsPpsLength)
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return SFrameCompatibilityPrefixBuffer { prefixDeltaFrame, sizeof(prefixDeltaFrame), { } };
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// Search for next NALU to compute the real spsPpsLength, including the next 00 00 00 01.
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findNalus(frameData, frameSize, spsPpsLength + 1, [&spsPpsLength](auto position) {
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spsPpsLength = position;
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return true;
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});
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Vector<uint8_t> buffer;
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buffer.resize(spsPpsLength + 2);
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std::memcpy(buffer.data(), frameData, spsPpsLength);
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buffer[spsPpsLength] = 0x25;
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buffer[spsPpsLength + 1] = 0xb8;
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return { buffer.data(), buffer.size(), WTFMove(buffer) };
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}
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static inline void findEscapeRbspPatterns(const Vector<uint8_t>& frame, size_t offset, const Function<void(size_t, bool)>& callback)
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{
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size_t numConsecutiveZeros = 0;
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auto* data = frame.data();
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for (size_t i = offset; i < frame.size(); ++i) {
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bool shouldEscape = data[i] <= 3 && numConsecutiveZeros >= 2;
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if (shouldEscape)
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numConsecutiveZeros = 0;
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if (data[i] == 0)
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++numConsecutiveZeros;
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else
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numConsecutiveZeros = 0;
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callback(i, shouldEscape);
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}
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}
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void toRbsp(Vector<uint8_t>& frame, size_t offset)
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{
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size_t count = 0;
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findEscapeRbspPatterns(frame, offset, [&count](size_t, bool shoudlBeEscaped) {
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if (shoudlBeEscaped)
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count++;
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});
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if (!count)
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return;
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Vector<uint8_t> newFrame;
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newFrame.reserveInitialCapacity(frame.size() + count);
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newFrame.append(frame.data(), offset);
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findEscapeRbspPatterns(frame, offset, [data = frame.data(), &newFrame](size_t position, bool shoudlBeEscaped) {
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if (shoudlBeEscaped)
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newFrame.uncheckedAppend(3);
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newFrame.uncheckedAppend(data[position]);
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});
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frame = WTFMove(newFrame);
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}
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static inline bool isVP8KeyFrame(const uint8_t* frame, size_t size)
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{
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ASSERT_UNUSED(size, size);
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return !(*frame & 0x01);
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}
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size_t computeVP8PrefixOffset(const uint8_t* frame, size_t size)
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{
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return isVP8KeyFrame(frame, size) ? 10 : 3;
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}
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SFrameCompatibilityPrefixBuffer computeVP8PrefixBuffer(const uint8_t* frame, size_t size)
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{
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Vector<uint8_t> prefix;
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prefix.append(frame, isVP8KeyFrame(frame, size) ? 10 : 3);
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return { prefix.data(), prefix.size(), WTFMove(prefix) };
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}
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} // namespace WebCore
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#endif // ENABLE(WEB_RTC)
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