1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef FRAMEWORKS_EX_VARIABLESPEED_JNI_RING_BUFFER_H_ 18 #define FRAMEWORKS_EX_VARIABLESPEED_JNI_RING_BUFFER_H_ 19 20 #include <vector> 21 22 #include "integral_types.h" 23 #include "macros.h" 24 25 // Circular buffer of multichannel audio, maintaining the position of the 26 // writing head and several reading head, and providing a method for 27 // accessing a contiguous block (through direct reference or the copy in a 28 // temporary read buffer in case the requested block crosses the buffer 29 // boundaries). 30 // 31 // This code is not thread-safe. 32 33 namespace video_editing { 34 35 class RingBuffer { 36 public: 37 RingBuffer(); 38 virtual ~RingBuffer(); 39 40 // Initializes a RingBuffer. 41 // @param size: size of the buffer in frames. 42 // @param num_channels: number of channels of the original audio. 43 // @param num_readers: number of reading heads. 44 void Init(int size, int num_channels, int num_readers); 45 46 // Gets the position of a reading head. 47 // @param reader reading head index. 48 // @returns position pointed to by the #reader reading head. 49 int64 Tell(int reader) const; 50 51 // Moves a reading head. 52 // @param reader reading head index. 53 // @param position target position. 54 void Seek(int reader, int64 position); 55 56 // Reads samples for a reading head. 57 // @param reader reading head index. 58 // @param num_frames number of frames to read. 59 // @param destination float buffer to which the samples will be written. 60 void Copy(int reader, float* destination, int num_frames) const; 61 62 // Writes samples. 63 // @param samples float buffer containing the samples. 64 // @param num_frames number of frames to write. 65 void Write(const float* samples, int num_frames); 66 67 // Flushes the content of the buffer and reset the position of the heads. 68 void Reset(); 69 70 // Returns the number of frames we can still write. 71 int overhead() const; 72 73 // Returns the number of frames we can read for a given reader. 74 // @param reader reading head index. 75 int available(int reader) const; 76 77 // Returns a pointer to num_frames x num_channels contiguous samples for 78 // a given reader. In most cases this directly returns a pointer to the 79 // data in the ring buffer. However, if the required block wraps around the 80 // boundaries of the ring buffer, the data is copied to a temporary buffer 81 // owned by the RingBuffer object. 82 // @param reader reading head index. 83 // @param num_frames number of frames to read. 84 // @returns pointer to a continuous buffer containing num_frames. 85 float* GetPointer(int reader, int num_frames); 86 87 // Merges updated data back into the ring buffer, if it was updated in 88 // the temporary buffer. This operation follows a GetPointer() that 89 // was used to obtain data to rewrite. The buffer address supplied 90 // here must match the one returned by GetPointer(). 91 // @param reader reading head index. 92 // @param source pointer to a continuous buffer containing num_frames. 93 // @param num_frames number of frames to copy back to the ring buffer. 94 void MergeBack(int reader, const float* source, int num_frames); 95 96 private: 97 // Returns the position of the laziest reader. 98 int64 GetTail() const; 99 100 bool initialized_; 101 float* samples_; 102 std::vector<int64> readers_; 103 int size_; 104 int num_channels_; 105 int num_readers_; 106 int64 head_logical_; 107 int head_; 108 109 float* temp_read_buffer_; 110 int temp_read_buffer_size_; 111 112 DISALLOW_COPY_AND_ASSIGN(RingBuffer); 113 }; 114 115 } // namespace video_editing 116 117 #endif // FRAMEWORKS_EX_VARIABLESPEED_JNI_RING_BUFFER_H_ 118
