1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/AudioCompactor.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,121 @@
1.4 +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* vim: set ts=8 sts=2 et sw=2 tw=80: */
1.6 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.7 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.8 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.9 +#if !defined(AudioCompactor_h)
1.10 +#define AudioCompactor_h
1.11 +
1.12 +#include "MediaQueue.h"
1.13 +#include "MediaData.h"
1.14 +#include "VideoUtils.h"
1.15 +
1.16 +namespace mozilla {
1.17 +
1.18 +class AudioCompactor
1.19 +{
1.20 +public:
1.21 + AudioCompactor(MediaQueue<AudioData>& aQueue)
1.22 + : mQueue(aQueue)
1.23 + { }
1.24 +
1.25 + // Push audio data into the underlying queue with minimal heap allocation
1.26 + // slop. This method is responsible for allocating AudioDataValue[] buffers.
1.27 + // The caller must provide a functor to copy the data into the buffers. The
1.28 + // functor must provide the following signature:
1.29 + //
1.30 + // uint32_t operator()(AudioDataValue *aBuffer, uint32_t aSamples);
1.31 + //
1.32 + // The functor must copy as many complete frames as possible to the provided
1.33 + // buffer given its length (in AudioDataValue elements). The number of frames
1.34 + // copied must be returned. This copy functor must support being called
1.35 + // multiple times in order to copy the audio data fully. The copy functor
1.36 + // must copy full frames as partial frames will be ignored.
1.37 + template<typename CopyFunc>
1.38 + bool Push(int64_t aOffset, int64_t aTime, int32_t aSampleRate,
1.39 + uint32_t aFrames, uint32_t aChannels, CopyFunc aCopyFunc)
1.40 + {
1.41 + // If we are losing more than a reasonable amount to padding, try to chunk
1.42 + // the data.
1.43 + size_t maxSlop = AudioDataSize(aFrames, aChannels) / MAX_SLOP_DIVISOR;
1.44 +
1.45 + while (aFrames > 0) {
1.46 + uint32_t samples = GetChunkSamples(aFrames, aChannels, maxSlop);
1.47 + nsAutoArrayPtr<AudioDataValue> buffer(new AudioDataValue[samples]);
1.48 +
1.49 + // Copy audio data to buffer using caller-provided functor.
1.50 + uint32_t framesCopied = aCopyFunc(buffer, samples);
1.51 +
1.52 + NS_ASSERTION(framesCopied <= aFrames, "functor copied too many frames");
1.53 +
1.54 + CheckedInt64 duration = FramesToUsecs(framesCopied, aSampleRate);
1.55 + if (!duration.isValid()) {
1.56 + return false;
1.57 + }
1.58 +
1.59 + mQueue.Push(new AudioData(aOffset,
1.60 + aTime,
1.61 + duration.value(),
1.62 + framesCopied,
1.63 + buffer.forget(),
1.64 + aChannels));
1.65 +
1.66 + // Remove the frames we just pushed into the queue and loop if there is
1.67 + // more to be done.
1.68 + aTime += duration.value();
1.69 + aFrames -= framesCopied;
1.70 +
1.71 + // NOTE: No need to update aOffset as its only an approximation anyway.
1.72 + }
1.73 +
1.74 + return true;
1.75 + }
1.76 +
1.77 + // Copy functor suitable for copying audio samples already in the
1.78 + // AudioDataValue format/layout expected by AudioStream on this platform.
1.79 + class NativeCopy
1.80 + {
1.81 + public:
1.82 + NativeCopy(const uint8_t* aSource, size_t aSourceBytes,
1.83 + uint32_t aChannels)
1.84 + : mSource(aSource)
1.85 + , mSourceBytes(aSourceBytes)
1.86 + , mChannels(aChannels)
1.87 + , mNextByte(0)
1.88 + { }
1.89 +
1.90 + uint32_t operator()(AudioDataValue *aBuffer, uint32_t aSamples);
1.91 +
1.92 + private:
1.93 + const uint8_t* const mSource;
1.94 + const size_t mSourceBytes;
1.95 + const uint32_t mChannels;
1.96 + size_t mNextByte;
1.97 + };
1.98 +
1.99 + // Allow 12.5% slop before chunking kicks in. Public so that the gtest can
1.100 + // access it.
1.101 + static const size_t MAX_SLOP_DIVISOR = 8;
1.102 +
1.103 +private:
1.104 + // Compute the number of AudioDataValue samples that will be fit the most
1.105 + // frames while keeping heap allocation slop less than the given threshold.
1.106 + static uint32_t
1.107 + GetChunkSamples(uint32_t aFrames, uint32_t aChannels, size_t aMaxSlop);
1.108 +
1.109 + static size_t BytesPerFrame(uint32_t aChannels)
1.110 + {
1.111 + return sizeof(AudioDataValue) * aChannels;
1.112 + }
1.113 +
1.114 + static size_t AudioDataSize(uint32_t aFrames, uint32_t aChannels)
1.115 + {
1.116 + return aFrames * BytesPerFrame(aChannels);
1.117 + }
1.118 +
1.119 + MediaQueue<AudioData> &mQueue;
1.120 +};
1.121 +
1.122 +} // namespace mozilla
1.123 +
1.124 +#endif // AudioCompactor_h
