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Diffstat (limited to '')
| -rw-r--r-- | dom/media/encoder/OpusTrackEncoder.cpp | 454 |
1 files changed, 454 insertions, 0 deletions
diff --git a/dom/media/encoder/OpusTrackEncoder.cpp b/dom/media/encoder/OpusTrackEncoder.cpp new file mode 100644 index 0000000000..16b71d378e --- /dev/null +++ b/dom/media/encoder/OpusTrackEncoder.cpp @@ -0,0 +1,454 @@ +/* -*- 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 "OpusTrackEncoder.h" +#include "nsString.h" +#include "mozilla/CheckedInt.h" +#include "mozilla/ProfilerLabels.h" +#include "VideoUtils.h" + +#include <opus/opus.h> + +#define LOG(args, ...) + +namespace mozilla { + +// The Opus format supports up to 8 channels, and supports multitrack audio up +// to 255 channels, but the current implementation supports only mono and +// stereo, and downmixes any more than that. +constexpr int MAX_SUPPORTED_AUDIO_CHANNELS = 8; + +// http://www.opus-codec.org/docs/html_api-1.0.2/group__opus__encoder.html +// In section "opus_encoder_init", channels must be 1 or 2 of input signal. +constexpr int MAX_CHANNELS = 2; + +// A maximum data bytes for Opus to encode. +constexpr int MAX_DATA_BYTES = 4096; + +// http://tools.ietf.org/html/draft-ietf-codec-oggopus-00#section-4 +// Second paragraph, " The granule position of an audio data page is in units +// of PCM audio samples at a fixed rate of 48 kHz." +constexpr int kOpusSamplingRate = 48000; + +// The duration of an Opus frame, and it must be 2.5, 5, 10, 20, 40 or 60 ms. +constexpr int kFrameDurationMs = 20; + +// The supported sampling rate of input signal (Hz), +// must be one of the following. Will resampled to 48kHz otherwise. +constexpr int kOpusSupportedInputSamplingRates[] = {8000, 12000, 16000, 24000, + 48000}; + +namespace { + +// An endian-neutral serialization of integers. Serializing T in little endian +// format to aOutput, where T is a 16 bits or 32 bits integer. +template <typename T> +static void SerializeToBuffer(T aValue, nsTArray<uint8_t>* aOutput) { + for (uint32_t i = 0; i < sizeof(T); i++) { + aOutput->AppendElement((uint8_t)(0x000000ff & (aValue >> (i * 8)))); + } +} + +static inline void SerializeToBuffer(const nsCString& aComment, + nsTArray<uint8_t>* aOutput) { + // Format of serializing a string to buffer is, the length of string (32 bits, + // little endian), and the string. + SerializeToBuffer((uint32_t)(aComment.Length()), aOutput); + aOutput->AppendElements(aComment.get(), aComment.Length()); +} + +static void SerializeOpusIdHeader(uint8_t aChannelCount, uint16_t aPreskip, + uint32_t aInputSampleRate, + nsTArray<uint8_t>* aOutput) { + // The magic signature, null terminator has to be stripped off from strings. + constexpr uint8_t magic[] = "OpusHead"; + aOutput->AppendElements(magic, sizeof(magic) - 1); + + // The version must always be 1 (8 bits, unsigned). + aOutput->AppendElement(1); + + // Number of output channels (8 bits, unsigned). + aOutput->AppendElement(aChannelCount); + + // Number of samples (at 48 kHz) to discard from the decoder output when + // starting playback (16 bits, unsigned, little endian). + SerializeToBuffer(aPreskip, aOutput); + + // The sampling rate of input source (32 bits, unsigned, little endian). + SerializeToBuffer(aInputSampleRate, aOutput); + + // Output gain, an encoder should set this field to zero (16 bits, signed, + // little endian). + SerializeToBuffer((int16_t)0, aOutput); + + // Channel mapping family. Family 0 allows only 1 or 2 channels (8 bits, + // unsigned). + aOutput->AppendElement(0); +} + +static void SerializeOpusCommentHeader(const nsCString& aVendor, + const nsTArray<nsCString>& aComments, + nsTArray<uint8_t>* aOutput) { + // The magic signature, null terminator has to be stripped off. + constexpr uint8_t magic[] = "OpusTags"; + aOutput->AppendElements(magic, sizeof(magic) - 1); + + // The vendor; Should append in the following order: + // vendor string length (32 bits, unsigned, little endian) + // vendor string. + SerializeToBuffer(aVendor, aOutput); + + // Add comments; Should append in the following order: + // comment list length (32 bits, unsigned, little endian) + // comment #0 string length (32 bits, unsigned, little endian) + // comment #0 string + // comment #1 string length (32 bits, unsigned, little endian) + // comment #1 string ... + SerializeToBuffer((uint32_t)aComments.Length(), aOutput); + for (uint32_t i = 0; i < aComments.Length(); ++i) { + SerializeToBuffer(aComments[i], aOutput); + } +} + +bool IsSampleRateSupported(TrackRate aSampleRate) { + // According to www.opus-codec.org, creating an opus encoder requires the + // sampling rate of source signal be one of 8000, 12000, 16000, 24000, or + // 48000. If this constraint is not satisfied, we resample the input to 48kHz. + AutoTArray<int, 5> supportedSamplingRates; + supportedSamplingRates.AppendElements( + kOpusSupportedInputSamplingRates, + ArrayLength(kOpusSupportedInputSamplingRates)); + return supportedSamplingRates.Contains(aSampleRate); +} + +} // Anonymous namespace. + +OpusTrackEncoder::OpusTrackEncoder(TrackRate aTrackRate, + MediaQueue<EncodedFrame>& aEncodedDataQueue) + : AudioTrackEncoder(aTrackRate, aEncodedDataQueue), + mOutputSampleRate(IsSampleRateSupported(aTrackRate) ? aTrackRate + : kOpusSamplingRate), + mEncoder(nullptr), + mLookahead(0), + mLookaheadWritten(0), + mResampler(nullptr), + mNumOutputFrames(0) {} + +OpusTrackEncoder::~OpusTrackEncoder() { + if (mEncoder) { + opus_encoder_destroy(mEncoder); + } + if (mResampler) { + speex_resampler_destroy(mResampler); + mResampler = nullptr; + } +} + +nsresult OpusTrackEncoder::Init(int aChannels) { + NS_ENSURE_TRUE((aChannels <= MAX_SUPPORTED_AUDIO_CHANNELS) && (aChannels > 0), + NS_ERROR_FAILURE); + + // This version of encoder API only support 1 or 2 channels, + // So set the mChannels less or equal 2 and + // let InterleaveTrackData downmix pcm data. + mChannels = aChannels > MAX_CHANNELS ? MAX_CHANNELS : aChannels; + + // Reject non-audio sample rates. + NS_ENSURE_TRUE(mTrackRate >= 8000, NS_ERROR_INVALID_ARG); + NS_ENSURE_TRUE(mTrackRate <= 192000, NS_ERROR_INVALID_ARG); + + if (NeedsResampler()) { + int error; + mResampler = speex_resampler_init(mChannels, mTrackRate, kOpusSamplingRate, + SPEEX_RESAMPLER_QUALITY_DEFAULT, &error); + + if (error != RESAMPLER_ERR_SUCCESS) { + return NS_ERROR_FAILURE; + } + } + + int error = 0; + mEncoder = opus_encoder_create(mOutputSampleRate, mChannels, + OPUS_APPLICATION_AUDIO, &error); + + if (error != OPUS_OK) { + return NS_ERROR_FAILURE; + } + + if (mAudioBitrate) { + int bps = static_cast<int>( + std::min<uint32_t>(mAudioBitrate, std::numeric_limits<int>::max())); + error = opus_encoder_ctl(mEncoder, OPUS_SET_BITRATE(bps)); + if (error != OPUS_OK) { + return NS_ERROR_FAILURE; + } + } + + // In the case of Opus we need to calculate the codec delay based on the + // pre-skip. For more information see: + // https://tools.ietf.org/html/rfc7845#section-4.2 + error = opus_encoder_ctl(mEncoder, OPUS_GET_LOOKAHEAD(&mLookahead)); + if (error != OPUS_OK) { + mLookahead = 0; + return NS_ERROR_FAILURE; + } + + SetInitialized(); + + return NS_OK; +} + +int OpusTrackEncoder::GetLookahead() const { + return mLookahead * kOpusSamplingRate / mOutputSampleRate; +} + +int OpusTrackEncoder::NumInputFramesPerPacket() const { + return mTrackRate * kFrameDurationMs / 1000; +} + +int OpusTrackEncoder::NumOutputFramesPerPacket() const { + return mOutputSampleRate * kFrameDurationMs / 1000; +} + +bool OpusTrackEncoder::NeedsResampler() const { + // A resampler is needed when mTrackRate is not supported by the opus encoder. + // This is equivalent to !IsSampleRateSupported(mTrackRate) but less cycles. + return mTrackRate != mOutputSampleRate && + mOutputSampleRate == kOpusSamplingRate; +} + +already_AddRefed<TrackMetadataBase> OpusTrackEncoder::GetMetadata() { + AUTO_PROFILER_LABEL("OpusTrackEncoder::GetMetadata", OTHER); + + MOZ_ASSERT(mInitialized); + + if (!mInitialized) { + return nullptr; + } + + RefPtr<OpusMetadata> meta = new OpusMetadata(); + meta->mChannels = mChannels; + meta->mSamplingFrequency = mTrackRate; + + // Ogg and Webm timestamps are always sampled at 48k for Opus. + SerializeOpusIdHeader(mChannels, + mLookahead * (kOpusSamplingRate / mOutputSampleRate), + mTrackRate, &meta->mIdHeader); + + nsCString vendor; + vendor.AppendASCII(opus_get_version_string()); + + nsTArray<nsCString> comments; + comments.AppendElement( + nsLiteralCString("ENCODER=Mozilla" MOZ_APP_UA_VERSION)); + + SerializeOpusCommentHeader(vendor, comments, &meta->mCommentHeader); + + return meta.forget(); +} + +nsresult OpusTrackEncoder::Encode(AudioSegment* aSegment) { + AUTO_PROFILER_LABEL("OpusTrackEncoder::Encode", OTHER); + + MOZ_ASSERT(aSegment); + MOZ_ASSERT(mInitialized || mCanceled); + + if (mCanceled || IsEncodingComplete()) { + return NS_ERROR_FAILURE; + } + + if (!mInitialized) { + // calculation below depends on the truth that mInitialized is true. + return NS_ERROR_FAILURE; + } + + int result = 0; + // Loop until we run out of packets of input data + while (result >= 0 && !IsEncodingComplete()) { + // re-sampled frames left last time which didn't fit into an Opus packet + // duration. + const int framesLeft = mResampledLeftover.Length() / mChannels; + MOZ_ASSERT(NumOutputFramesPerPacket() >= framesLeft); + // Fetch input frames such that there will be n frames where (n + + // framesLeft) >= NumOutputFramesPerPacket() after re-sampling. + const int framesToFetch = NumInputFramesPerPacket() - + (framesLeft * mTrackRate / kOpusSamplingRate) + + (NeedsResampler() ? 1 : 0); + + if (!mEndOfStream && aSegment->GetDuration() < framesToFetch) { + // Not enough raw data + return NS_OK; + } + + // Start encoding data. + AutoTArray<AudioDataValue, 9600> pcm; + pcm.SetLength(NumOutputFramesPerPacket() * mChannels); + + int frameCopied = 0; + + for (AudioSegment::ChunkIterator iter(*aSegment); + !iter.IsEnded() && frameCopied < framesToFetch; iter.Next()) { + AudioChunk chunk = *iter; + + // Chunk to the required frame size. + TrackTime frameToCopy = + std::min(chunk.GetDuration(), + static_cast<TrackTime>(framesToFetch - frameCopied)); + + // Possible greatest value of framesToFetch = 3844: see + // https://bugzilla.mozilla.org/show_bug.cgi?id=1349421#c8. frameToCopy + // should not be able to exceed this value. + MOZ_ASSERT(frameToCopy <= 3844, "frameToCopy exceeded expected range"); + + if (!chunk.IsNull()) { + // Append the interleaved data to the end of pcm buffer. + AudioTrackEncoder::InterleaveTrackData( + chunk, frameToCopy, mChannels, + pcm.Elements() + frameCopied * mChannels); + } else { + CheckedInt<int> memsetLength = + CheckedInt<int>(frameToCopy) * mChannels * sizeof(AudioDataValue); + if (!memsetLength.isValid()) { + // This should never happen, but we use a defensive check because + // we really don't want a bad memset + MOZ_ASSERT_UNREACHABLE("memsetLength invalid!"); + return NS_ERROR_FAILURE; + } + memset(pcm.Elements() + frameCopied * mChannels, 0, + memsetLength.value()); + } + + frameCopied += frameToCopy; + } + + // Possible greatest value of framesToFetch = 3844: see + // https://bugzilla.mozilla.org/show_bug.cgi?id=1349421#c8. frameCopied + // should not be able to exceed this value. + MOZ_ASSERT(frameCopied <= 3844, "frameCopied exceeded expected range"); + + int framesInPCM = frameCopied; + if (mResampler) { + AutoTArray<AudioDataValue, 9600> resamplingDest; + uint32_t inframes = frameCopied; + uint32_t outframes = inframes * kOpusSamplingRate / mTrackRate + 1; + + // We want to consume all the input data, so we slightly oversize the + // resampled data buffer so we can fit the output data in. We cannot + // really predict the output frame count at each call. + resamplingDest.SetLength(outframes * mChannels); + +#if MOZ_SAMPLE_TYPE_S16 + short* in = reinterpret_cast<short*>(pcm.Elements()); + short* out = reinterpret_cast<short*>(resamplingDest.Elements()); + speex_resampler_process_interleaved_int(mResampler, in, &inframes, out, + &outframes); +#else + float* in = reinterpret_cast<float*>(pcm.Elements()); + float* out = reinterpret_cast<float*>(resamplingDest.Elements()); + speex_resampler_process_interleaved_float(mResampler, in, &inframes, out, + &outframes); +#endif + + MOZ_ASSERT(pcm.Length() >= mResampledLeftover.Length()); + PodCopy(pcm.Elements(), mResampledLeftover.Elements(), + mResampledLeftover.Length()); + + uint32_t outframesToCopy = std::min( + outframes, + static_cast<uint32_t>(NumOutputFramesPerPacket() - framesLeft)); + + MOZ_ASSERT(pcm.Length() - mResampledLeftover.Length() >= + outframesToCopy * mChannels); + PodCopy(pcm.Elements() + mResampledLeftover.Length(), + resamplingDest.Elements(), outframesToCopy * mChannels); + int frameLeftover = outframes - outframesToCopy; + mResampledLeftover.SetLength(frameLeftover * mChannels); + PodCopy(mResampledLeftover.Elements(), + resamplingDest.Elements() + outframesToCopy * mChannels, + mResampledLeftover.Length()); + // This is always at 48000Hz. + framesInPCM = framesLeft + outframesToCopy; + } + + // Remove the raw data which has been pulled to pcm buffer. + // The value of frameCopied should be equal to (or smaller than, if eos) + // NumOutputFramesPerPacket(). + aSegment->RemoveLeading(frameCopied); + + // Has reached the end of input stream and all queued data has pulled for + // encoding. + bool isFinalPacket = false; + if (aSegment->GetDuration() == 0 && mEndOfStream && + framesInPCM < NumOutputFramesPerPacket()) { + // Pad |mLookahead| samples to the end of the track to prevent loss of + // original data. + const int toWrite = std::min(mLookahead - mLookaheadWritten, + NumOutputFramesPerPacket() - framesInPCM); + PodZero(pcm.Elements() + framesInPCM * mChannels, toWrite * mChannels); + mLookaheadWritten += toWrite; + framesInPCM += toWrite; + if (mLookaheadWritten == mLookahead) { + isFinalPacket = true; + } + } + + MOZ_ASSERT_IF(!isFinalPacket, framesInPCM == NumOutputFramesPerPacket()); + + // Append null data to pcm buffer if the leftover data is not enough for + // opus encoder. + if (framesInPCM < NumOutputFramesPerPacket() && isFinalPacket) { + PodZero(pcm.Elements() + framesInPCM * mChannels, + (NumOutputFramesPerPacket() - framesInPCM) * mChannels); + } + auto frameData = MakeRefPtr<EncodedFrame::FrameData>(); + // Encode the data with Opus Encoder. + frameData->SetLength(MAX_DATA_BYTES); + // result is returned as opus error code if it is negative. + result = 0; +#ifdef MOZ_SAMPLE_TYPE_S16 + const opus_int16* pcmBuf = static_cast<opus_int16*>(pcm.Elements()); + result = opus_encode(mEncoder, pcmBuf, NumOutputFramesPerPacket(), + frameData->Elements(), MAX_DATA_BYTES); +#else + const float* pcmBuf = static_cast<float*>(pcm.Elements()); + result = opus_encode_float(mEncoder, pcmBuf, NumOutputFramesPerPacket(), + frameData->Elements(), MAX_DATA_BYTES); +#endif + frameData->SetLength(result >= 0 ? result : 0); + + if (result < 0) { + LOG("[Opus] Fail to encode data! Result: %s.", opus_strerror(result)); + } + if (isFinalPacket) { + if (mResampler) { + speex_resampler_destroy(mResampler); + mResampler = nullptr; + } + mResampledLeftover.SetLength(0); + } + + // timestamp should be the time of the first sample + mEncodedDataQueue.Push(MakeAndAddRef<EncodedFrame>( + media::TimeUnit(mNumOutputFrames + mLookahead, mOutputSampleRate), + static_cast<uint64_t>(framesInPCM) * kOpusSamplingRate / + mOutputSampleRate, + kOpusSamplingRate, EncodedFrame::OPUS_AUDIO_FRAME, + std::move(frameData))); + + mNumOutputFrames += NumOutputFramesPerPacket(); + LOG("[Opus] mOutputTimeStamp %.3f.", + media::TimeUnit(mNumOutputFrames, mOutputSampleRate).ToSeconds()); + + if (isFinalPacket) { + LOG("[Opus] Done encoding."); + mEncodedDataQueue.Finish(); + } + } + + return result >= 0 ? NS_OK : NS_ERROR_FAILURE; +} + +} // namespace mozilla + +#undef LOG |