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Diffstat (limited to 'chromium/media/filters/wsola_internals.h')
-rw-r--r-- | chromium/media/filters/wsola_internals.h | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/chromium/media/filters/wsola_internals.h b/chromium/media/filters/wsola_internals.h new file mode 100644 index 00000000000..55fff04d30b --- /dev/null +++ b/chromium/media/filters/wsola_internals.h @@ -0,0 +1,93 @@ +// 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]|. +// +// Then compute the |extremum| point -b / (2*a) and |extremum_value| +// b^2 / (4*a) - b^2 / (2*a) + c. +// +// It is not expected that this function is called with +// y[0] == y[1] == y[2]. +MEDIA_EXPORT void CubicInterpolation(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 GetSymmetricHanningWindow(int window_length, float* window); + +} // namespace internal + +} // namespace media + +#endif // MEDIA_FILTERS_WSOLA_INTERNALS_H_ |