root/trunk/libffado/src/libutil/TimestampedBuffer.h

Revision 1001, 7.8 kB (checked in by ppalmers, 14 years ago)

Improve streaming startup for better initial timestamps and locking.

Line 
1 /*
2  * Copyright (C) 2005-2008 by Pieter Palmers
3  *
4  * This file is part of FFADO
5  * FFADO = Free Firewire (pro-)audio drivers for linux
6  *
7  * FFADO is based upon FreeBoB.
8  *
9  * This program is free software: you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation, either version 2 of the License, or
12  * (at your option) version 3 of the License.
13  *
14  * This program is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17  * GNU General Public License for more details.
18  *
19  * You should have received a copy of the GNU General Public License
20  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
21  *
22  */
23
24 #ifndef __FFADO_TIMESTAMPEDBUFFER__
25 #define __FFADO_TIMESTAMPEDBUFFER__
26
27 #include "../debugmodule/debugmodule.h"
28 #include "libutil/ringbuffer.h"
29 #include <pthread.h>
30
31 //typedef float ffado_timestamp_t;
32 //#define TIMESTAMP_FORMAT_SPEC "%14.3f"
33 typedef double ffado_timestamp_t;
34 #define TIMESTAMP_FORMAT_SPEC "%14.3f"
35 // typedef int64_t ffado_timestamp_t;
36 // #define TIMESTAMP_FORMAT_SPEC "%012lld"
37
38 namespace Util
39 {
40
41 class TimestampedBufferClient;
42
43 /**
44     * \brief Class implementing a frame buffer that is time-aware
45     *
46     * This class implements a buffer that is time-aware. Whenever new frames
47     * are written to the buffer, the timestamp corresponding to the last frame
48     * in the buffer is updated. This allows to calculate the timestamp of any
49     * other frame in the buffer.
50     *
51     * The buffer is a frame buffer, having the following parameters defining
52     * it's behaviour:
53     * - buff_size: buffer size in frames (setBufferSize())
54     * - events_per_frame: the number of events per frame (setEventsPerFrame())
55     * - event_size: the storage size of the events (in bytes) (setEventSize())
56     *
57     * The total size of the buffer (in bytes) is at least
58     * buff_size*events_per_frame*event_size.
59     *
60     * Timestamp tracking is done by requiring that a timestamp is specified every
61     * time frames are added to the buffer. In combination with the buffer fill and
62     * the frame rate (calculated internally), this allows to calculate the timestamp
63     * of any frame in the buffer. In order to initialize the internal data structures,
64     * the setNominalRate() and setUpdatePeriod() functions are provided.
65     *
66     * \note Currently the class only supports fixed size writes of size update_period.
67     *       This can change in the future, implementation ideas are already in place.
68     *
69     * The TimestampedBuffer class is time unit agnostic. It can handle any time unit
70     * as long as it fits in a 64 bit unsigned integer. The buffer supports wrapped
71     * timestamps using (...).
72     *
73     * There are two methods of reading and writing to the buffer.
74     *
75     * The first method uses conventional readFrames() and writeFrames() functions.
76     *
77     * The second method makes use of the TimestampedBufferClient interface. When a
78     * TimestampedBuffer is created, it is required that a TimestampedBufferClient is
79     * registered. This client implements the processReadBlock and processWriteBlock
80     * functions. These are block processing 'callbacks' that allow zero-copy processing
81     * of the buffer contents. In order to initiate block processing, the
82     * blockProcessWriteFrames and blockProcessReadFrames functions are provided by
83     * TimestampedBuffer.
84     *
85     */
86 class TimestampedBuffer
87 {
88     public:
89         TimestampedBuffer ( TimestampedBufferClient * );
90         virtual ~TimestampedBuffer();
91
92         bool writeDummyFrame();
93         bool dropFrames ( unsigned int nbframes );
94
95         bool writeFrames ( unsigned int nbframes, char *data, ffado_timestamp_t ts );
96         bool readFrames ( unsigned int nbframes, char *data );
97
98         bool preloadFrames ( unsigned int nbframes, char *data, bool keep_head_ts );
99
100         bool blockProcessWriteFrames ( unsigned int nbframes, ffado_timestamp_t ts );
101         bool blockProcessReadFrames ( unsigned int nbframes );
102
103         bool prepare();
104         bool clearBuffer();
105
106         bool isEnabled() {return m_enabled;};
107         void enable() {m_enabled=true;};
108         void disable() {m_enabled=false;};
109
110         bool isTransparent() {return m_transparent;};
111         void setTransparent ( bool v ) {m_transparent=v;};
112
113         bool setEventSize ( unsigned int s );
114         bool setEventsPerFrame ( unsigned int s );
115         bool setBufferSize ( unsigned int s );
116         unsigned int getBufferSize() {return m_buffer_size;};
117
118         unsigned int getBytesPerFrame() {return m_bytes_per_frame;};
119
120         bool setWrapValue ( ffado_timestamp_t w );
121
122         unsigned int getBufferFill();
123         unsigned int getBufferSpace();
124
125         // timestamp stuff
126         int getFrameCounter() {return m_framecounter;};
127
128         void getBufferHeadTimestamp ( ffado_timestamp_t *ts, signed int *fc );
129         void getBufferTailTimestamp ( ffado_timestamp_t *ts, signed int *fc );
130
131         void setBufferTailTimestamp ( ffado_timestamp_t new_timestamp );
132         void setBufferHeadTimestamp ( ffado_timestamp_t new_timestamp );
133
134         ffado_timestamp_t getTimestampFromTail ( int nframes );
135         ffado_timestamp_t getTimestampFromHead ( int nframes );
136
137         // dll stuff
138         bool setNominalRate ( float r );
139         float getNominalRate() {return m_nominal_rate;};
140         float getRate();
141         void setRate(float rate);
142
143         bool setUpdatePeriod ( unsigned int t );
144         unsigned int getUpdatePeriod();
145
146         // misc stuff
147         void dumpInfo();
148         void setVerboseLevel ( int l ) {setDebugLevel ( l );};
149
150     private:
151         void decrementFrameCounter(unsigned int nbframes);
152         void incrementFrameCounter(unsigned int nbframes, ffado_timestamp_t new_timestamp);
153         void resetFrameCounter();
154
155     protected:
156
157         ffado_ringbuffer_t * m_event_buffer;
158         char* m_process_buffer;
159         unsigned int m_cluster_size;
160         unsigned int m_process_block_size;
161
162         unsigned int m_event_size; // the size of one event
163         unsigned int m_events_per_frame; // the number of events in a frame
164         unsigned int m_buffer_size; // the number of frames in the buffer
165         unsigned int m_bytes_per_frame;
166         unsigned int m_bytes_per_buffer;
167         bool m_enabled; // you can get frames FIXME: rename!!
168         bool m_transparent; // the buffer should hold the frames put in it. if true, discards all frames
169
170         ffado_timestamp_t m_wrap_at; // value to wrap at
171
172         TimestampedBufferClient *m_Client;
173
174         DECLARE_DEBUG_MODULE;
175
176     private:
177         // the framecounter gives the number of frames in the buffer
178         signed int m_framecounter;
179
180         // the buffer tail timestamp gives the timestamp of the last frame
181         // that was put into the buffer
182         ffado_timestamp_t   m_buffer_tail_timestamp;
183         ffado_timestamp_t   m_buffer_next_tail_timestamp;
184
185         // this mutex protects the access to the framecounter
186         // and the buffer head timestamp.
187         pthread_mutex_t m_framecounter_lock;
188
189         // tracking DLL variables
190 // JMW: try double for this too
191 //    float m_dll_e2;
192         double m_dll_e2;
193         float m_dll_b;
194         float m_dll_c;
195
196         float m_nominal_rate;
197         float calculateRate();
198         float m_current_rate;
199         unsigned int m_update_period;
200 };
201
202 /**
203     * \brief Interface to be implemented by TimestampedBuffer clients
204     */
205 class TimestampedBufferClient
206 {
207     public:
208         TimestampedBufferClient() {};
209         virtual ~TimestampedBufferClient() {};
210
211         virtual bool processReadBlock ( char *data, unsigned int nevents, unsigned int offset ) =0;
212         virtual bool processWriteBlock ( char *data, unsigned int nevents, unsigned int offset ) =0;
213
214 };
215
216 } // end of namespace Util
217
218 #endif /* __FFADO_TIMESTAMPEDBUFFER__ */
219
220
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