/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/ /* 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/. */ #include "EbmlComposer.h" #include "mozilla/UniquePtr.h" #include "mozilla/EndianUtils.h" #include "libmkv/EbmlIDs.h" #include "libmkv/EbmlWriter.h" #include "libmkv/WebMElement.h" #include "prtime.h" #include "limits.h" namespace mozilla { // Timecode scale in nanoseconds static const unsigned long TIME_CODE_SCALE = 1000000; // The WebM header size without audio CodecPrivateData static const int32_t DEFAULT_HEADER_SIZE = 1024; void EbmlComposer::GenerateHeader() { // Write the EBML header. EbmlGlobal ebml; // The WEbM header default size usually smaller than 1k. auto buffer = MakeUnique<uint8_t[]>(DEFAULT_HEADER_SIZE + mCodecPrivateData.Length()); ebml.buf = buffer.get(); ebml.offset = 0; writeHeader(&ebml); { EbmlLoc segEbmlLoc, ebmlLocseg, ebmlLoc; Ebml_StartSubElement(&ebml, &segEbmlLoc, Segment); { Ebml_StartSubElement(&ebml, &ebmlLocseg, SeekHead); // Todo: We don't know the exact sizes of encoded data and // ignore this section. Ebml_EndSubElement(&ebml, &ebmlLocseg); writeSegmentInformation(&ebml, &ebmlLoc, TIME_CODE_SCALE, 0); { EbmlLoc trackLoc; Ebml_StartSubElement(&ebml, &trackLoc, Tracks); { // Video if (mWidth > 0 && mHeight > 0) { writeVideoTrack(&ebml, 0x1, 0, "V_VP8", mWidth, mHeight, mDisplayWidth, mDisplayHeight, mFrameRate); } // Audio if (mCodecPrivateData.Length() > 0) { // Extract the pre-skip from mCodecPrivateData // then convert it to nanoseconds. // Details in OpusTrackEncoder.cpp. mCodecDelay = (uint64_t)LittleEndian::readUint16(mCodecPrivateData.Elements() + 10) * PR_NSEC_PER_SEC / 48000; // Fixed 80ms, convert into nanoseconds. uint64_t seekPreRoll = 80 * PR_NSEC_PER_MSEC; writeAudioTrack(&ebml, 0x2, 0x0, "A_OPUS", mSampleFreq, mChannels, mCodecDelay, seekPreRoll, mCodecPrivateData.Elements(), mCodecPrivateData.Length()); } } Ebml_EndSubElement(&ebml, &trackLoc); } } // The Recording length is unknown and // ignore write the whole Segment element size } MOZ_ASSERT(ebml.offset <= DEFAULT_HEADER_SIZE + mCodecPrivateData.Length(), "write more data > EBML_BUFFER_SIZE"); auto block = mClusterBuffs.AppendElement(); block->SetLength(ebml.offset); memcpy(block->Elements(), ebml.buf, ebml.offset); mFlushState |= FLUSH_METADATA; } void EbmlComposer::FinishMetadata() { if (mFlushState & FLUSH_METADATA) { // We don't remove the first element of mClusterBuffs because the // |mClusterHeaderIndex| may have value. mClusterCanFlushBuffs.AppendElement()->SwapElements(mClusterBuffs[0]); mFlushState &= ~FLUSH_METADATA; } } void EbmlComposer::FinishCluster() { FinishMetadata(); if (!(mFlushState & FLUSH_CLUSTER)) { // No completed cluster available. return; } MOZ_ASSERT(mClusterLengthLoc > 0); EbmlGlobal ebml; EbmlLoc ebmlLoc; ebmlLoc.offset = mClusterLengthLoc; ebml.offset = 0; for (uint32_t i = mClusterHeaderIndex; i < mClusterBuffs.Length(); i++) { ebml.offset += mClusterBuffs[i].Length(); } ebml.buf = mClusterBuffs[mClusterHeaderIndex].Elements(); Ebml_EndSubElement(&ebml, &ebmlLoc); // Move the mClusterBuffs data from mClusterHeaderIndex that we can skip // the metadata and the rest P-frames after ContainerWriter::FLUSH_NEEDED. for (uint32_t i = mClusterHeaderIndex; i < mClusterBuffs.Length(); i++) { mClusterCanFlushBuffs.AppendElement()->SwapElements(mClusterBuffs[i]); } mClusterHeaderIndex = 0; mClusterLengthLoc = 0; mClusterBuffs.Clear(); mFlushState &= ~FLUSH_CLUSTER; } void EbmlComposer::WriteSimpleBlock(EncodedFrame* aFrame) { EbmlGlobal ebml; ebml.offset = 0; auto frameType = aFrame->GetFrameType(); bool flush = false; bool isVP8IFrame = (frameType == EncodedFrame::FrameType::VP8_I_FRAME); if (isVP8IFrame) { FinishCluster(); flush = true; } else { // Force it to calculate timecode using signed math via cast int64_t timeCode = (aFrame->GetTimeStamp() / ((int) PR_USEC_PER_MSEC) - mClusterTimecode) + (mCodecDelay / PR_NSEC_PER_MSEC); if (timeCode < SHRT_MIN || timeCode > SHRT_MAX ) { // We're probably going to overflow (or underflow) the timeCode value later! FinishCluster(); flush = true; } } auto block = mClusterBuffs.AppendElement(); block->SetLength(aFrame->GetFrameData().Length() + DEFAULT_HEADER_SIZE); ebml.buf = block->Elements(); if (flush) { EbmlLoc ebmlLoc; Ebml_StartSubElement(&ebml, &ebmlLoc, Cluster); MOZ_ASSERT(mClusterBuffs.Length() > 0); // current cluster header array index mClusterHeaderIndex = mClusterBuffs.Length() - 1; mClusterLengthLoc = ebmlLoc.offset; // if timeCode didn't under/overflow before, it shouldn't after this mClusterTimecode = aFrame->GetTimeStamp() / PR_USEC_PER_MSEC; Ebml_SerializeUnsigned(&ebml, Timecode, mClusterTimecode); mFlushState |= FLUSH_CLUSTER; } bool isOpus = (frameType == EncodedFrame::FrameType::OPUS_AUDIO_FRAME); // Can't underflow/overflow now int64_t timeCode = aFrame->GetTimeStamp() / ((int) PR_USEC_PER_MSEC) - mClusterTimecode; if (isOpus) { timeCode += mCodecDelay / PR_NSEC_PER_MSEC; } MOZ_ASSERT(timeCode >= SHRT_MIN && timeCode <= SHRT_MAX); writeSimpleBlock(&ebml, isOpus ? 0x2 : 0x1, static_cast<short>(timeCode), isVP8IFrame, 0, 0, (unsigned char*)aFrame->GetFrameData().Elements(), aFrame->GetFrameData().Length()); MOZ_ASSERT(ebml.offset <= DEFAULT_HEADER_SIZE + aFrame->GetFrameData().Length(), "write more data > EBML_BUFFER_SIZE"); block->SetLength(ebml.offset); } void EbmlComposer::SetVideoConfig(uint32_t aWidth, uint32_t aHeight, uint32_t aDisplayWidth, uint32_t aDisplayHeight, float aFrameRate) { MOZ_ASSERT(aWidth > 0, "Width should > 0"); MOZ_ASSERT(aHeight > 0, "Height should > 0"); MOZ_ASSERT(aDisplayWidth > 0, "DisplayWidth should > 0"); MOZ_ASSERT(aDisplayHeight > 0, "DisplayHeight should > 0"); MOZ_ASSERT(aFrameRate > 0, "FrameRate should > 0"); mWidth = aWidth; mHeight = aHeight; mDisplayWidth = aDisplayWidth; mDisplayHeight = aDisplayHeight; mFrameRate = aFrameRate; } void EbmlComposer::SetAudioConfig(uint32_t aSampleFreq, uint32_t aChannels) { MOZ_ASSERT(aSampleFreq > 0, "SampleFreq should > 0"); MOZ_ASSERT(aChannels > 0, "Channels should > 0"); mSampleFreq = aSampleFreq; mChannels = aChannels; } void EbmlComposer::ExtractBuffer(nsTArray<nsTArray<uint8_t> >* aDestBufs, uint32_t aFlag) { if ((aFlag & ContainerWriter::FLUSH_NEEDED) || (aFlag & ContainerWriter::GET_HEADER)) { FinishMetadata(); } if (aFlag & ContainerWriter::FLUSH_NEEDED) { FinishCluster(); } // aDestBufs may have some element for (uint32_t i = 0; i < mClusterCanFlushBuffs.Length(); i++) { aDestBufs->AppendElement()->SwapElements(mClusterCanFlushBuffs[i]); } mClusterCanFlushBuffs.Clear(); } EbmlComposer::EbmlComposer() : mFlushState(FLUSH_NONE) , mClusterHeaderIndex(0) , mClusterLengthLoc(0) , mCodecDelay(0) , mClusterTimecode(0) , mWidth(0) , mHeight(0) , mFrameRate(0) , mSampleFreq(0) , mChannels(0) {} } // namespace mozilla