CallbackDataSource.h revision 69d3d8a9540b0da787ea0beccad2517f057dd54d 
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    virtual String8 toString() {
42        return mName;
43    }
44
45private:
46    sp<IDataSource> mIDataSource;
47    sp<IMemory> mMemory;
48    bool mIsClosed;
49    String8 mName;
50
51    DISALLOW_EVIL_CONSTRUCTORS(CallbackDataSource);
52};
53
54
55// A caching DataSource that wraps a CallbackDataSource. For reads smaller
56// than kCacheSize it will read up to kCacheSize ahead and cache it.
57// This reduces the number of binder round trips to the IDataSource and has a significant
58// impact on time taken for filetype sniffing and metadata extraction.
59class TinyCacheSource : public DataSource {
60public:
61    TinyCacheSource(const sp<DataSource>& source);
62
63    virtual status_t initCheck() const;
64    virtual ssize_t readAt(off64_t offset, void* data, size_t size);
65    virtual status_t getSize(off64_t* size);
66    virtual uint32_t flags();
67    virtual void close() { mSource->close(); }
68    virtual String8 toString() {
69        return mName;
70    }
71
72private:
73    // 2kb comes from experimenting with the time-to-first-frame from a MediaPlayer
74    // with an in-memory MediaDataSource source on a Nexus 5. Beyond 2kb there was
75    // no improvement.
76    enum {
77        kCacheSize = 2048,
78    };
79
80    sp<DataSource> mSource;
81    uint8_t mCache[kCacheSize];
82    off64_t mCachedOffset;
83    size_t mCachedSize;
84    String8 mName;
85
86    DISALLOW_EVIL_CONSTRUCTORS(TinyCacheSource);
87};
88
89}; // namespace android
90
91#endif // ANDROID_CALLBACKDATASOURCE_H
92