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Commit e053bfaa authored by Kevin Rocard's avatar Kevin Rocard
Browse files

libaudioprocessing: clamp application provided float audio 



For security reason, float buffers provided by application must be
clamped to FLOAT_NOMINAL_RANGE_HEADROOM.
With the new all float pipeline, float are no longer clamped by their
conversion to fixed point.

This patch adds a float buffer provider that clamps float samples
as they are copied to audio pipeline.

Test: Play music, play video in chrome (opensles format float),
      play float pcm audio file specially crafter with >> 1 samples.
Bug: 68099072
Change-Id: I220b436d9982bc43a75715a030efd0e6a0c79fa3
Signed-off-by: default avatarKevin Rocard <krocard@google.com>
parent c3d554d4

media/libaudioprocessing/AudioMixer.cpp

+8 −0
Original line number Diff line number Diff line
@@ -314,6 +314,14 @@ status_t AudioMixer::Track::prepareForReformat() 
                targetFormat,

                kCopyBufferFrameCount));

        requiresReconfigure = true;

    } else if (mFormat == AUDIO_FORMAT_PCM_FLOAT) {

        // Input and output are floats, make sure application did not provide > 3db samples

        // that would break volume application (b/68099072)

        // TODO: add a trusted source flag to avoid the overhead

        mReformatBufferProvider.reset(new ClampFloatBufferProvider(

                audio_channel_count_from_out_mask(channelMask),

                kCopyBufferFrameCount));

        requiresReconfigure = true;

    }

    if (targetFormat != mMixerInFormat) {

        mPostDownmixReformatBufferProvider.reset(new ReformatBufferProvider(

media/libaudioprocessing/BufferProviders.cpp

+17 −0
Original line number Diff line number Diff line
@@ -376,6 +376,23 @@ void ReformatBufferProvider::copyFrames(void *dst, const void *src, size_t frame 
    memcpy_by_audio_format(dst, mOutputFormat, src, mInputFormat, frames * mChannelCount);

}



ClampFloatBufferProvider::ClampFloatBufferProvider(int32_t channelCount, size_t bufferFrameCount) :

        CopyBufferProvider(

                channelCount * audio_bytes_per_sample(AUDIO_FORMAT_PCM_FLOAT),

                channelCount * audio_bytes_per_sample(AUDIO_FORMAT_PCM_FLOAT),

                bufferFrameCount),

        mChannelCount(channelCount)

{

    ALOGV("ClampFloatBufferProvider(%p)(%u)", this, channelCount);

}



void ClampFloatBufferProvider::copyFrames(void *dst, const void *src, size_t frames)

{

    memcpy_to_float_from_float_with_clamping((float*)dst, (const float*)src,

                                             frames * mChannelCount,

                                             FLOAT_NOMINAL_RANGE_HEADROOM);

}



TimestretchBufferProvider::TimestretchBufferProvider(int32_t channelCount,

        audio_format_t format, uint32_t sampleRate, const AudioPlaybackRate &playbackRate) :

        mChannelCount(channelCount),

media/libmedia/include/media/BufferProviders.h

+11 −0
Original line number Diff line number Diff line
@@ -161,6 +161,17 @@ protected: 
    const audio_format_t mOutputFormat;

};



// ClampFloatBufferProvider derives from CopyBufferProvider to clamp floats inside -3db

class ClampFloatBufferProvider : public CopyBufferProvider {

public:

    ClampFloatBufferProvider(int32_t channelCount,

            size_t bufferFrameCount);

    virtual void copyFrames(void *dst, const void *src, size_t frames);



protected:

    const uint32_t       mChannelCount;

};



// TimestretchBufferProvider derives from PassthruBufferProvider for time stretching

class TimestretchBufferProvider : public PassthruBufferProvider {

public: