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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "media/base/multi_channel_resampler.h" | 5 #include "media/base/multi_channel_resampler.h" |
6 | 6 |
7 #include "base/bind.h" | 7 #include "base/bind.h" |
8 #include "base/bind_helpers.h" | 8 #include "base/bind_helpers.h" |
9 #include "base/logging.h" | 9 #include "base/logging.h" |
10 #include "media/base/audio_bus.h" | 10 #include "media/base/audio_bus.h" |
11 | 11 |
12 namespace media { | 12 namespace media { |
13 | 13 |
14 MultiChannelResampler::MultiChannelResampler(int channels, | 14 MultiChannelResampler::MultiChannelResampler(int channels, |
15 double io_sample_rate_ratio, | 15 double io_sample_rate_ratio, |
16 size_t request_size, | |
16 const ReadCB& read_cb) | 17 const ReadCB& read_cb) |
17 : last_frame_count_(0), | 18 : last_frame_count_(0), |
18 read_cb_(read_cb), | 19 read_cb_(read_cb), |
19 output_frames_ready_(0) { | 20 output_frames_ready_(0) { |
20 // Allocate each channel's resampler. | 21 // Allocate each channel's resampler. |
21 resamplers_.reserve(channels); | 22 resamplers_.reserve(channels); |
22 for (int i = 0; i < channels; ++i) { | 23 for (int i = 0; i < channels; ++i) { |
23 resamplers_.push_back(new SincResampler(io_sample_rate_ratio, base::Bind( | 24 resamplers_.push_back(new SincResampler( |
24 &MultiChannelResampler::ProvideInput, base::Unretained(this), i))); | 25 io_sample_rate_ratio, request_size, base::Bind( |
26 &MultiChannelResampler::ProvideInput, base::Unretained(this), i))); | |
25 } | 27 } |
26 } | 28 } |
27 | 29 |
28 MultiChannelResampler::~MultiChannelResampler() {} | 30 MultiChannelResampler::~MultiChannelResampler() {} |
29 | 31 |
30 void MultiChannelResampler::Resample(AudioBus* audio_bus, int frames) { | 32 void MultiChannelResampler::Resample(AudioBus* audio_bus, int frames) { |
31 DCHECK_EQ(static_cast<size_t>(audio_bus->channels()), resamplers_.size()); | 33 DCHECK_EQ(static_cast<size_t>(audio_bus->channels()), resamplers_.size()); |
32 | 34 |
35 // Optimize the single channel case to avoid chunking. | |
henrika (OOO until Aug 14)
2013/04/27 19:43:40
"chunking"? Is that a well known term?
DaleCurtis
2013/04/29 22:12:31
Refers to the code section below. I've updated th
| |
36 if (audio_bus->channels() == 1) { | |
37 resamplers_[0]->Resample(audio_bus->channel(0), frames); | |
38 return; | |
39 } | |
40 | |
33 // We need to ensure that SincResampler only calls ProvideInput once for each | 41 // We need to ensure that SincResampler only calls ProvideInput once for each |
34 // channel. To ensure this, we chunk the number of requested frames into | 42 // channel. To ensure this, we chunk the number of requested frames into |
35 // SincResampler::ChunkSize() sized chunks. SincResampler guarantees it will | 43 // SincResampler::ChunkSize() sized chunks. SincResampler guarantees it will |
36 // only call ProvideInput() once when we resample this way. | 44 // only call ProvideInput() once when we resample this way. |
37 output_frames_ready_ = 0; | 45 output_frames_ready_ = 0; |
38 int chunk_size = resamplers_[0]->ChunkSize(); | |
39 while (output_frames_ready_ < frames) { | 46 while (output_frames_ready_ < frames) { |
47 int chunk_size = resamplers_[0]->ChunkSize(); | |
40 int frames_this_time = std::min(frames - output_frames_ready_, chunk_size); | 48 int frames_this_time = std::min(frames - output_frames_ready_, chunk_size); |
41 | 49 |
42 // Resample each channel. | 50 // Resample each channel. |
43 for (size_t i = 0; i < resamplers_.size(); ++i) { | 51 for (size_t i = 0; i < resamplers_.size(); ++i) { |
44 DCHECK_EQ(chunk_size, resamplers_[i]->ChunkSize()); | 52 DCHECK_EQ(chunk_size, resamplers_[i]->ChunkSize()); |
45 | 53 |
46 // Depending on the sample-rate scale factor, and the internal buffering | 54 // Depending on the sample-rate scale factor, and the internal buffering |
47 // used in a SincResampler kernel, this call to Resample() will only | 55 // used in a SincResampler kernel, this call to Resample() will only |
48 // sometimes call ProvideInput(). However, if it calls ProvideInput() for | 56 // sometimes call ProvideInput(). However, if it calls ProvideInput() for |
49 // the first channel, then it will call it for the remaining channels, | 57 // the first channel, then it will call it for the remaining channels, |
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100 for (size_t i = 0; i < resamplers_.size(); ++i) | 108 for (size_t i = 0; i < resamplers_.size(); ++i) |
101 resamplers_[i]->Flush(); | 109 resamplers_[i]->Flush(); |
102 } | 110 } |
103 | 111 |
104 void MultiChannelResampler::SetRatio(double io_sample_rate_ratio) { | 112 void MultiChannelResampler::SetRatio(double io_sample_rate_ratio) { |
105 for (size_t i = 0; i < resamplers_.size(); ++i) | 113 for (size_t i = 0; i < resamplers_.size(); ++i) |
106 resamplers_[i]->SetRatio(io_sample_rate_ratio); | 114 resamplers_[i]->SetRatio(io_sample_rate_ratio); |
107 } | 115 } |
108 | 116 |
109 } // namespace media | 117 } // namespace media |
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