1 /*
2  * Copyright (C) 2007 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_AUDIO_BUFFER_PROVIDER_H
18 #define ANDROID_AUDIO_BUFFER_PROVIDER_H
19 
20 #include <utils/Errors.h>
21 
22 namespace android {
23 // ----------------------------------------------------------------------------
24 
25 class AudioBufferProvider
26 {
27 public:
28 
29     // FIXME merge with AudioTrackShared::Buffer, AudioTrack::Buffer, and AudioRecord::Buffer
30     //       and rename getNextBuffer() to obtainBuffer()
31     struct Buffer {
BufferBuffer32         Buffer() : raw(NULL), frameCount(0) { }
33         union {
34             void*       raw;
35             short*      i16;
36             int8_t*     i8;
37         };
38         size_t frameCount;
39     };
40 
~AudioBufferProvider()41     virtual ~AudioBufferProvider() {}
42 
43     // value representing an invalid presentation timestamp
44     static const int64_t kInvalidPTS = 0x7FFFFFFFFFFFFFFFLL;    // <stdint.h> is too painful
45 
46     // pts is the local time when the next sample yielded by getNextBuffer
47     // will be rendered.
48     // Pass kInvalidPTS if the PTS is unknown or not applicable.
49     // On entry:
50     //  buffer              != NULL
51     //  buffer->raw         unused
52     //  buffer->frameCount  maximum number of desired frames
53     // On successful return:
54     //  status              NO_ERROR
55     //  buffer->raw         non-NULL pointer to buffer->frameCount contiguous available frames
56     //  buffer->frameCount  number of contiguous available frames at buffer->raw,
57     //                      0 < buffer->frameCount <= entry value
58     // On error return:
59     //  status              != NO_ERROR
60     //  buffer->raw         NULL
61     //  buffer->frameCount  0
62     virtual status_t getNextBuffer(Buffer* buffer, int64_t pts = kInvalidPTS) = 0;
63 
64     // Release (a portion of) the buffer previously obtained by getNextBuffer().
65     // It is permissible to call releaseBuffer() multiple times per getNextBuffer().
66     // On entry:
67     //  buffer->frameCount  number of frames to release, must be <= number of frames
68     //                      obtained but not yet released
69     //  buffer->raw         unused
70     // On return:
71     //  buffer->frameCount  0; implementation MUST set to zero
72     //  buffer->raw         undefined; implementation is PERMITTED to set to any value,
73     //                      so if caller needs to continue using this buffer it must
74     //                      keep track of the pointer itself
75     virtual void releaseBuffer(Buffer* buffer) = 0;
76 };
77 
78 // ----------------------------------------------------------------------------
79 }; // namespace android
80 
81 #endif // ANDROID_AUDIO_BUFFER_PROVIDER_H
82