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- // Copyright 2013 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- // A set of utility functions to perform WSOLA.
- #ifndef MEDIA_FILTERS_WSOLA_INTERNALS_H_
- #define MEDIA_FILTERS_WSOLA_INTERNALS_H_
- #include <utility>
- #include "media/base/media_export.h"
- namespace media {
- class AudioBus;
- namespace internal {
- typedef std::pair<int, int> Interval;
- // Dot-product of channels of two AudioBus. For each AudioBus an offset is
- // given. |dot_product[k]| is the dot-product of channel |k|. The caller should
- // allocate sufficient space for |dot_product|.
- MEDIA_EXPORT void MultiChannelDotProduct(const AudioBus* a,
- int frame_offset_a,
- const AudioBus* b,
- int frame_offset_b,
- int num_frames,
- float* dot_product);
- // Energies of sliding windows of channels are interleaved.
- // The number windows is |input->frames()| - (|frames_per_window| - 1), hence,
- // the method assumes |energy| must be, at least, of size
- // (|input->frames()| - (|frames_per_window| - 1)) * |input->channels()|.
- MEDIA_EXPORT void MultiChannelMovingBlockEnergies(const AudioBus* input,
- int frames_per_window,
- float* energy);
- // Fit the curve f(x) = a * x^2 + b * x + c such that
- // f(-1) = y[0]
- // f(0) = y[1]
- // f(1) = y[2]
- // and return the maximum, assuming that y[0] <= y[1] >= y[2].
- MEDIA_EXPORT void QuadraticInterpolation(const float* y_values,
- float* extremum,
- float* extremum_value);
- // Search a subset of all candid blocks. The search is performed every
- // |decimation| frames. This reduces complexity by a factor of about
- // 1 / |decimation|. A cubic interpolation is used to have a better estimate of
- // the best match.
- MEDIA_EXPORT int DecimatedSearch(int decimation,
- Interval exclude_interval,
- const AudioBus* target_block,
- const AudioBus* search_segment,
- const float* energy_target_block,
- const float* energy_candid_blocks);
- // Search [|low_limit|, |high_limit|] of |search_segment| to find a block that
- // is most similar to |target_block|. |energy_target_block| is the energy of the
- // |target_block|. |energy_candidate_blocks| is the energy of all blocks within
- // |search_block|.
- MEDIA_EXPORT int FullSearch(int low_limit,
- int hight_limimit,
- Interval exclude_interval,
- const AudioBus* target_block,
- const AudioBus* search_block,
- const float* energy_target_block,
- const float* energy_candidate_blocks);
- // Find the index of the block, within |search_block|, that is most similar
- // to |target_block|. Obviously, the returned index is w.r.t. |search_block|.
- // |exclude_interval| is an interval that is excluded from the search.
- MEDIA_EXPORT int OptimalIndex(const AudioBus* search_block,
- const AudioBus* target_block,
- Interval exclude_interval);
- // Return a "periodic" Hann window. This is the first L samples of an L+1
- // Hann window. It is perfect reconstruction for overlap-and-add.
- MEDIA_EXPORT void GetPeriodicHanningWindow(int window_length, float* window);
- } // namespace internal
- } // namespace media
- #endif // MEDIA_FILTERS_WSOLA_INTERNALS_H_
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