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ece6a51e5b
Add voice transcoding during phone call with two basic transforms: - sample rate downscaling by a factor of 2 with a decimator - sample rate upscaling by a factor of 2 with an interpolator (no low-pass filter) Signed-off-by: Marcin Smoczyński <smoczynski.marcin@gmail.com>
87 lines
2.8 KiB
C++
87 lines
2.8 KiB
C++
// Copyright (c) 2017-2021, Mudita Sp. z.o.o. All rights reserved.
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// For licensing, see https://github.com/mudita/MuditaOS/LICENSE.md
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#pragma once
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#include <Audio/AudioFormat.hpp>
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#include <Audio/AbstractStream.hpp>
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namespace audio::transcode
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{
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/**
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* @brief Data transform which can be applied on a data range.
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*/
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class Transform
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{
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public:
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using Span = audio::AbstractStream::Span;
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virtual ~Transform() = default;
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/**
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* @brief Transforms data within range
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*
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* @param inputSpan - input data to transform
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* @param outputSpan - space for transformation output
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* @return Output data
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*/
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virtual auto transform(const Span &inputSpan, const Span &outputSpan) const -> Span = 0;
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/**
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* @brief Checks if audio format is suitable for transformation.
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*
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* @param inputFormat - format to be checked
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* @return true if inputFormat is suitable for transformation, false otherwise
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*/
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virtual auto validateInputFormat(const audio::AudioFormat &inputFormat) const noexcept -> bool = 0;
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/**
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* @brief Calculates the audio format on transform output based on the
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* input format.
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*
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* @param inputFormat - format of the data on input
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* @return format of the data on output.
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*/
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virtual auto transformFormat(const audio::AudioFormat &inputFormat) const noexcept -> audio::AudioFormat = 0;
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/**
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* @brief Calculates the size of an output data after the transform.
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*
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* @param blockSize - size of an input block
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* @return size of an output block
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*/
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virtual auto transformBlockSize(std::size_t blockSize) const noexcept -> std::size_t = 0;
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/**
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* @brief Calculates required size of an input data to get transformed data of size equal
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* outputBlockSize
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*
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* @param outputBlockSize - size of an output block
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* @return std::size_t
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*/
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virtual auto transformBlockSizeInverted(std::size_t outputBlockSize) const noexcept -> std::size_t = 0;
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/**
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* @brief A convenience transform operator.
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*/
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inline auto operator()(const Span &span, const Span &transformSpace)
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{
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return transform(span, transformSpace);
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}
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/**
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* @brief A convenience wrapper for transforms which has transcoding size
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* same as output size and a transcoding operation is performed in-place.
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*
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* @param span to transform
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* @return transformed span
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*/
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inline auto transform(const Span &span)
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{
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return transform(span, span);
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}
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};
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}; // namespace audio::transcode
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