CallbackDataSource.h revision fbe7fcfe818b6f68e352c7c450d4fe15a543b801
1/* 2 * Copyright 2015 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 ANDROID_CALLBACKDATASOURCE_H 18#define ANDROID_CALLBACKDATASOURCE_H 19 20#include <media/stagefright/DataSource.h> 21#include <media/stagefright/foundation/ADebug.h> 22 23namespace android { 24 25class IDataSource; 26class IMemory; 27 28// A stagefright DataSource that wraps a binder IDataSource. It's a "Callback" 29// DataSource because it calls back to the IDataSource for data. 30class CallbackDataSource : public DataSource { 31public: 32 CallbackDataSource(const sp<IDataSource>& iDataSource); 33 virtual ~CallbackDataSource(); 34 35 // DataSource implementation. 36 virtual status_t initCheck() const; 37 virtual ssize_t readAt(off64_t offset, void *data, size_t size); 38 virtual status_t getSize(off64_t *size); 39 virtual uint32_t flags(); 40 virtual void close(); 41 42private: 43 sp<IDataSource> mIDataSource; 44 sp<IMemory> mMemory; 45 bool mIsClosed; 46 47 DISALLOW_EVIL_CONSTRUCTORS(CallbackDataSource); 48}; 49 50 51// A caching DataSource that wraps a CallbackDataSource. For reads smaller 52// than kCacheSize it will read up to kCacheSize ahead and cache it. 53// This reduces the number of binder round trips to the IDataSource and has a significant 54// impact on time taken for filetype sniffing and metadata extraction. 55class TinyCacheSource : public DataSource { 56public: 57 TinyCacheSource(const sp<DataSource>& source); 58 59 virtual status_t initCheck() const; 60 virtual ssize_t readAt(off64_t offset, void* data, size_t size); 61 virtual status_t getSize(off64_t* size); 62 virtual uint32_t flags(); 63 virtual void close() { mSource->close(); } 64 65private: 66 // 2kb comes from experimenting with the time-to-first-frame from a MediaPlayer 67 // with an in-memory MediaDataSource source on a Nexus 5. Beyond 2kb there was 68 // no improvement. 69 enum { 70 kCacheSize = 2048, 71 }; 72 73 sp<DataSource> mSource; 74 uint8_t mCache[kCacheSize]; 75 off64_t mCachedOffset; 76 size_t mCachedSize; 77 78 DISALLOW_EVIL_CONSTRUCTORS(TinyCacheSource); 79}; 80 81}; // namespace android 82 83#endif // ANDROID_CALLBACKDATASOURCE_H 84