1/*
2 * libjingle
3 * Copyright 2004--2010, Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifndef TALK_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_
29#define TALK_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_
30
31#include "talk/base/constructormagic.h"
32#include "talk/base/sigslot.h"
33
34namespace cricket {
35
36// Interface for outputting a stream to a playback device.
37// Semantics and thread-safety of EnableBufferMonitoring()/
38// DisableBufferMonitoring() are the same as for talk_base::Worker.
39class SoundOutputStreamInterface {
40 public:
41  virtual ~SoundOutputStreamInterface() {}
42
43  // Enables monitoring the available buffer space on the current thread.
44  virtual bool EnableBufferMonitoring() = 0;
45  // Disables the monitoring.
46  virtual bool DisableBufferMonitoring() = 0;
47
48  // Write the given samples to the devices. If currently monitoring then this
49  // may only be called from the monitoring thread.
50  virtual bool WriteSamples(const void *sample_data,
51                            size_t size) = 0;
52
53  // Retrieves the current output volume for this stream. Nominal range is
54  // defined by SoundSystemInterface::k(Max|Min)Volume, but values exceeding the
55  // max may be possible in some implementations. This call retrieves the actual
56  // volume currently in use by the OS, not a cached value from a previous
57  // (Get|Set)Volume() call.
58  virtual bool GetVolume(int *volume) = 0;
59
60  // Changes the output volume for this stream. Nominal range is defined by
61  // SoundSystemInterface::k(Max|Min)Volume. The effect of exceeding kMaxVolume
62  // is implementation-defined.
63  virtual bool SetVolume(int volume) = 0;
64
65  // Closes this stream object. If currently monitoring then this may only be
66  // called from the monitoring thread.
67  virtual bool Close() = 0;
68
69  // Get the latency of the stream.
70  virtual int LatencyUsecs() = 0;
71
72  // Notifies the producer of the available buffer space for writes.
73  // It fires continuously as long as the space is greater than zero.
74  // The first parameter is the amount of buffer space available for data to
75  // be written (i.e., the maximum amount of data that can be written right now
76  // with WriteSamples() without blocking).
77  // The 2nd parameter is the stream that is issuing the callback.
78  sigslot::signal2<size_t, SoundOutputStreamInterface *> SignalBufferSpace;
79
80 protected:
81  SoundOutputStreamInterface() {}
82
83 private:
84  DISALLOW_COPY_AND_ASSIGN(SoundOutputStreamInterface);
85};
86
87}  // namespace cricket
88
89#endif  // TALK_SOUND_SOUNDOUTPUTSTREAMINTERFACE_H_
90