VideoDecoder.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef META_OCEAN_MEDIA_ANDROID_VIDEO_DECODER_H
#define META_OCEAN_MEDIA_ANDROID_VIDEO_DECODER_H
 
#if defined(__ANDROID_API__) && __ANDROID_API__ >= 24
 
#ifndef OCEAN_MEDIA_ANDROID_VIDEODECODER_AVAILABLE
    #define OCEAN_MEDIA_ANDROID_VIDEODECODER_AVAILABLE
#endif
 
#include "ocean/media/android/Android.h"
#include "ocean/media/android/NativeMediaLibrary.h"
 
#include "ocean/base/Frame.h"
#include "ocean/base/Lock.h"
 
namespace Ocean
{
 
namespace Media
{
 
namespace Android
{
 
/**
 * This class implements a simple video decoder for Android using encoded media samples from memory as input.
 *
 * Usage:
 * @code
 * // a function which is e.g., running in a separate thread
 * void threadRun()
 * {
 *     VideoDecoder videoDecoder;
 *
 *     // initializing the decoder with the input format of the media samples
 *     if (!videoDecoder.initialize("video/avc", 1920u, 1080u))
 *     {
 *         // handle error
 *     }
 *
 *     if (!videoDecoder.start())
 *     {
 *         // handle error
 *     }
 *
 *     unsigned int frameIndex = 0u;
 *     double frameRate = 30.0;
 *
 *     while (true)
 *     {
 *         void* sampleData = nullptr;
 *         size_t sampleSize = 0;
 *
 *         // external function: function needs to provide the new media samples from an external source - e.g., from an external webcam, a video stream, etc.
 *         if (doesNewInputSampleExist(sampleData, &sampleSize))
 *         {
  *            // presentation time in microseconds
 *             uint64_t presentationTime = uint64_t(1.0e6 * double(frameIndex) / frameRate);
 *
 *             // we forward the media sample to the decoder, eventually it will be decoded and will be available through decodedFrame()
 *             if (!videoDecoder.pushSample(sampleData, sampleSize, presentationTime))
 *             {
 *                 // handle error
 *             }
 *
 *             ++frameIndex;
 *         }
 *
 *         // we simply check whether another frame has been decoded (there may be a delay between
 *         Frame newFrame = videoDecoder.popFrame();
 *
 *         if (newFrame.isValid())
 *         {
 *             // external function: receiving new frames and processes the frames
 *             sendFrameToReceiver(std::move(newFrame));
 *         }
 *     }
 * }
 * @endcode
 * @ingroup mediaandroid
 */
class VideoDecoder
{
    public:
 
        /**
         * Default constructor creating an un-initialized decoder.
         */
        VideoDecoder();
 
        /**
         * Move constructor.
         * @param videoDecoder The decoder to be moved
         */
        inline VideoDecoder(VideoDecoder&& videoDecoder) noexcept;
 
        /**
         * Destructs the video decoder and releases all associated resources.
         */
        ~VideoDecoder();
 
        /**
         * @param mime The MIME type (Multipurpose Internet Mail Extensions) of the video to be decoded, e.g., "video/avc", "video/hevc", ...
         * @param width The width of the video to be decoded, in pixel, with range [1, infinity)
         * @param height The height of the video to be decoded, in pixel, with range [1, infinity)
         * @return True, if succeeded
         * @see isInitialized().
         */
        bool initialize(const std::string& mime, const unsigned int width, const unsigned int height);
 
        /**
         * Starts the video decoder.
         * @return True, if succeeded
         * @see isStarted().
         */
        bool start();
 
        /**
         * Stops the video decoder.
         * @return True, if succeeded
         */
        bool stop();
 
        /**
         * Adds a new media sample which needs to be decoded to the video decoder.
         * The decoder needs to be initialized and started.<br>
         * The presentation time is mainly intended to allow associating the provided encoded media sample with the resulting decoded frame when calling popFrame().<br>
         * However, it's recommended to define a reasonable presentation time for each sample (e.g., let the first sample start at 0 and increment the time by 1^6/fps for each following sample.
         * @param data The data of the encoded media sample, must be valid
         * @param size The size of the encoded media sample, in bytes, with range [1, infinity)
         * @param presentationTime The presentation time of the sample, in microseconds, with range [0, infinity)
         * @return True, if succeeded
         * @see start(), isInitialized(), isStarted().
         */
        bool pushSample(const void* data, const size_t size, const uint64_t presentationTime);
 
        /**
         * Optional the frame's presentation time will be returned, this is the presentation time which was used when the corresponding sample was provided in decodedSample().
         * @param presentationTime Optional resulting presentation time in micro seconds, with range (-infinity, infinity)
         * @return The resulting frame, invalid if currently no decoded frame is available
         * @see pushSample().
         */
        Frame popFrame(int64_t* presentationTime = nullptr);
 
        /**
         * Returns whether this decode is initialized.
         * @return True, if so
         * @see initialize().
         */
        inline bool isInitialized() const;
 
        /**
         * Returns whether this decoder is currently running.
         * @return True, if so
         * @see start().
         */
        inline bool isStarted() const;
 
        /**
         * Explicitly releases this video encoder.
         * If the encoder is still running, the encoder will be stopped as well.
         */
        void release();
 
        /**
         * Move operator.
         * @param videoDecoder The video decoder to be moved
         * @return Reference to this object
         */
        inline VideoDecoder& operator=(VideoDecoder&& videoDecoder) noexcept;
 
        /**
         * Extracts the video frame from an output buffer of a video codec.
         * @param mediaCodec The media codec to which the output buffer belongs, must be valid
         * @param presentationTime Optional resulting presentation time in micro seconds, with range (-infinity, infinity)
         * @return The resulting extracted frame, invalid if the frame could not be extracted
         */
        static Frame extractVideoFrameFromCodecOutputBuffer(AMediaCodec* const mediaCodec, int64_t* presentationTime = nullptr);
 
    protected:
 
        /**
         * Disabled copy constructor.
         */
        VideoDecoder(const VideoDecoder&) = delete;
 
        /**
         * Disabled copy operator.
         * @return Reference to this object
         */
        VideoDecoder& operator=(const VideoDecoder&) = delete;
 
    protected:
 
        /// The subscription for the native media library.
        NativeMediaLibrary::ScopedSubscription nativeMediaLibrarySubscription_;
 
        /// The Android media decoder used to decode the video.
        NativeMediaLibrary::ScopedAMediaCodec decoder_;
 
        /// True, if the decoder is currently started.
        bool isStarted_ = false;
 
        /// The decoder's lock.
        mutable Lock lock_;
};
 
inline VideoDecoder::VideoDecoder(VideoDecoder&& videoDecoder) noexcept
{
    *this = std::move(videoDecoder);
}
 
inline bool VideoDecoder::isInitialized() const
{
    const ScopedLock scopedLock(lock_);
 
    return decoder_.isValid();
}
 
inline bool VideoDecoder::isStarted() const
{
    const ScopedLock scopedLock(lock_);
 
    ocean_assert(!isStarted_ || isInitialized());
 
    return isStarted_;
}
 
inline VideoDecoder& VideoDecoder::operator=(VideoDecoder&& videoDecoder) noexcept
{
    if (this != &videoDecoder)
    {
        release();
 
        decoder_ = std::move(videoDecoder.decoder_);
 
        isStarted_ = videoDecoder.isStarted_;
        videoDecoder.isStarted_ = false;
    }
 
    return *this;
}
 
}
 
}
 
}
 
#endif // defined(__ANDROID_API__) && __ANDROID_API__ >= 24
 
#endif // META_OCEAN_MEDIA_ANDROID_VIDEO_DECODER_H