| // Copyright (c) 2015 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. |
| |
| // Modifications Copyright 2019 The Cobalt Authors. All Rights Reserved. |
| // |
| // 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 COBALT_MEDIA_BASE_INTERLEAVED_SINC_RESAMPLER_H_ |
| #define COBALT_MEDIA_BASE_INTERLEAVED_SINC_RESAMPLER_H_ |
| |
| #include <memory> |
| #include <queue> |
| |
| #include "base/memory/aligned_memory.h" |
| #include "base/memory/ref_counted.h" |
| #include "cobalt/export.h" |
| |
| namespace cobalt { |
| namespace media { |
| |
| // InterleavedSincResampler is a high-quality interleaved multi-channel sample |
| // -rate converter operating on samples in float. It uses the same algorithm as |
| // SincResampler. Unlike SincResampler, it works in push mode instead of pull |
| // mode. |
| class COBALT_EXPORT InterleavedSincResampler { |
| public: |
| // |io_sample_rate_ratio| is the ratio of input / output sample rates. |
| // |channel_count| is the number of channels in the interleaved audio stream. |
| InterleavedSincResampler(double io_sample_rate_ratio, int channel_count); |
| ~InterleavedSincResampler(); |
| |
| // Append a buffer to the queue. The samples in the buffer has to be floats. |
| void QueueBuffer(const float* data, int frames); |
| void QueueBuffer(std::unique_ptr<float[]> data, int frames); |
| |
| // Resample |frames| of data from enqueued buffers. Return false if no sample |
| // is read. Return true if all requested samples have been written into |
| // |destination|. It will never do a partial read. After the stream reaches |
| // the end, the function will fill the rest of buffer with 0. |
| void Resample(float* destination, int frames); |
| |
| // Flush all buffered data and reset internal indices. |
| void Flush(); |
| |
| // Return false if we shouldn't queue more buffers to the resampler. |
| bool CanQueueBuffer() const; |
| |
| // Returning true when we start to return zero filled data because of EOS. |
| bool ReachedEOS() const; |
| |
| // Return true if the enqueued buffers have enough data for us to resample the |
| // requested number of frames. |
| bool HasEnoughData(int frames_to_resample) const; |
| |
| private: |
| class Buffer; |
| |
| void InitializeKernel(); |
| void Read(float* destination, int frames); |
| |
| float Convolve(const float* input_ptr, const float* k1, const float* k2, |
| double kernel_interpolation_factor); |
| |
| // The ratio of input / output sample rates. |
| double io_sample_rate_ratio_; |
| |
| // An index on the source input buffer with sub-sample precision. It must be |
| // double precision to avoid drift. |
| double virtual_source_idx_; |
| |
| // The buffer is primed once at the very beginning of processing. |
| bool buffer_primed_; |
| |
| // Number of audio channels. |
| int channel_count_; |
| |
| // The size of bytes for an audio frame. |
| const int frame_size_in_bytes_; |
| |
| // Contains kKernelOffsetCount kernels back-to-back, each of size kKernelSize. |
| // The kernel offsets are sub-sample shifts of a windowed sinc shifted from |
| // 0.0 to 1.0 sample. |
| std::unique_ptr<float, base::AlignedFreeDeleter> kernel_storage_; |
| |
| // Data from the source is copied into this buffer for each processing pass. |
| std::unique_ptr<float, base::AlignedFreeDeleter> input_buffer_; |
| |
| // A queue of buffers to be resampled. |
| std::queue<scoped_refptr<Buffer>> pending_buffers_; |
| |
| // The current offset to read when reading from the first pending buffer. |
| int offset_in_frames_; |
| |
| // The following two variables are used to calculate EOS and in HasEnoughData. |
| int frames_resampled_; |
| int frames_queued_; |
| |
| // Pointers to the various regions inside |input_buffer_|. See the diagram at |
| // the top of the .cc file for more information. |
| float* const r0_; |
| float* const r1_; |
| float* const r2_; |
| float* const r3_; |
| float* const r4_; |
| float* const r5_; |
| |
| DISALLOW_COPY_AND_ASSIGN(InterleavedSincResampler); |
| }; |
| |
| } // namespace media |
| } // namespace cobalt |
| |
| #endif // COBALT_MEDIA_BASE_INTERLEAVED_SINC_RESAMPLER_H_ |