services/audioflinger/BufferProviders.h

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef ANDROID_BUFFER_PROVIDERS_H
#define ANDROID_BUFFER_PROVIDERS_H

#include <stdint.h>
#include <sys/types.h>

#include <hardware/audio_effect.h>
#include <media/AudioBufferProvider.h>
#include <system/audio.h>

namespace android {

// ----------------------------------------------------------------------------

class PassthruBufferProvider : public AudioBufferProvider {
public:
    PassthruBufferProvider() : mTrackBufferProvider(NULL) { }

    virtual ~PassthruBufferProvider() { }

    // call this to release the buffer to the upstream provider.
    // treat it as an audio discontinuity for future samples.
    virtual void reset() { }

    // set the upstream buffer provider. Consider calling "reset" before this function.
    virtual void setBufferProvider(AudioBufferProvider *p) {
        mTrackBufferProvider = p;
    }

protected:
    AudioBufferProvider *mTrackBufferProvider;
};

// Base AudioBufferProvider class used for DownMixerBufferProvider, RemixBufferProvider,
// and ReformatBufferProvider.
// It handles a private buffer for use in converting format or channel masks from the
// input data to a form acceptable by the mixer.
// TODO: Make a ResamplerBufferProvider when integers are entirely removed from the
// processing pipeline.
class CopyBufferProvider : public PassthruBufferProvider {
public:
    // Use a private buffer of bufferFrameCount frames (each frame is outputFrameSize bytes).
    // If bufferFrameCount is 0, no private buffer is created and in-place modification of
    // the upstream buffer provider's buffers is performed by copyFrames().
    CopyBufferProvider(size_t inputFrameSize, size_t outputFrameSize,
            size_t bufferFrameCount);
    virtual ~CopyBufferProvider();

    // Overrides AudioBufferProvider methods
    virtual status_t getNextBuffer(Buffer *buffer, int64_t pts);
    virtual void releaseBuffer(Buffer *buffer);

    // Overrides PassthruBufferProvider
    virtual void reset();

    // this function should be supplied by the derived class.  It converts
    // #frames in the *src pointer to the *dst pointer.  It is public because
    // some providers will allow this to work on arbitrary buffers outside
    // of the internal buffers.
    virtual void copyFrames(void *dst, const void *src, size_t frames) = 0;

protected:
    const size_t         mInputFrameSize;
    const size_t         mOutputFrameSize;
private:
    AudioBufferProvider::Buffer mBuffer;
    const size_t         mLocalBufferFrameCount;
    void                *mLocalBufferData;
    size_t               mConsumed;
};

// DownmixerBufferProvider derives from CopyBufferProvider to provide
// position dependent downmixing by an Audio Effect.
class DownmixerBufferProvider : public CopyBufferProvider {
public:
    DownmixerBufferProvider(audio_channel_mask_t inputChannelMask,
            audio_channel_mask_t outputChannelMask, audio_format_t format,
            uint32_t sampleRate, int32_t sessionId, size_t bufferFrameCount);
    virtual ~DownmixerBufferProvider();
    //Overrides
    virtual void copyFrames(void *dst, const void *src, size_t frames);

    bool isValid() const { return mDownmixHandle != NULL; }
    static status_t init();
    static bool isMultichannelCapable() { return sIsMultichannelCapable; }

protected:
    effect_handle_t    mDownmixHandle;
    effect_config_t    mDownmixConfig;

    // effect descriptor for the downmixer used by the mixer
    static effect_descriptor_t sDwnmFxDesc;
    // indicates whether a downmix effect has been found and is usable by this mixer
    static bool                sIsMultichannelCapable;
    // FIXME: should we allow effects outside of the framework?
    // We need to here. A special ioId that must be <= -2 so it does not map to a session.
    static const int32_t SESSION_ID_INVALID_AND_IGNORED = -2;
};

// RemixBufferProvider derives from CopyBufferProvider to perform an
// upmix or downmix to the proper channel count and mask.
class RemixBufferProvider : public CopyBufferProvider {
public:
    RemixBufferProvider(audio_channel_mask_t inputChannelMask,
            audio_channel_mask_t outputChannelMask, audio_format_t format,
            size_t bufferFrameCount);
    //Overrides
    virtual void copyFrames(void *dst, const void *src, size_t frames);

protected:
    const audio_format_t mFormat;
    const size_t         mSampleSize;
    const size_t         mInputChannels;
    const size_t         mOutputChannels;
    int8_t               mIdxAry[sizeof(uint32_t) * 8]; // 32 bits => channel indices
};

// ReformatBufferProvider derives from CopyBufferProvider to convert the input data
// to an acceptable mixer input format type.
class ReformatBufferProvider : public CopyBufferProvider {
public:
    ReformatBufferProvider(int32_t channelCount,
            audio_format_t inputFormat, audio_format_t outputFormat,
            size_t bufferFrameCount);
    virtual void copyFrames(void *dst, const void *src, size_t frames);

protected:
    const uint32_t       mChannelCount;
    const audio_format_t mInputFormat;
    const audio_format_t mOutputFormat;
};

// ----------------------------------------------------------------------------
} // namespace android

#endif // ANDROID_BUFFER_PROVIDERS_H