IsochronousClockModel.cpp revision 87c9f646a94259d7c321c3b3d5947fa1778f5ac2 
1/*
2 * Copyright (C) 2016 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#define LOG_TAG "AAudio"
18//#define LOG_NDEBUG 0
19#include <utils/Log.h>
20
21#include <stdint.h>
22
23#include "utility/AudioClock.h"
24#include "IsochronousClockModel.h"
25
26#define MIN_LATENESS_NANOS (10 * AAUDIO_NANOS_PER_MICROSECOND)
27
28using namespace android;
29using namespace aaudio;
30
31IsochronousClockModel::IsochronousClockModel()
32        : mMarkerFramePosition(0)
33        , mMarkerNanoTime(0)
34        , mSampleRate(48000)
35        , mFramesPerBurst(64)
36        , mMaxLatenessInNanos(0)
37        , mState(STATE_STOPPED)
38{
39}
40
41IsochronousClockModel::~IsochronousClockModel() {
42}
43
44void IsochronousClockModel::start(int64_t nanoTime) {
45    ALOGD("IsochronousClockModel::start(nanos = %lld)\n", (long long) nanoTime);
46    mMarkerNanoTime = nanoTime;
47    mState = STATE_STARTING;
48}
49
50void IsochronousClockModel::stop(int64_t nanoTime) {
51    ALOGD("IsochronousClockModel::stop(nanos = %lld)\n", (long long) nanoTime);
52    mMarkerNanoTime = nanoTime;
53    mMarkerFramePosition = convertTimeToPosition(nanoTime); // TODO should we do this?
54    mState = STATE_STOPPED;
55}
56
57void IsochronousClockModel::processTimestamp(int64_t framePosition, int64_t nanoTime) {
58    int64_t framesDelta = framePosition - mMarkerFramePosition;
59    int64_t nanosDelta = nanoTime - mMarkerNanoTime;
60    if (nanosDelta < 1000) {
61        return;
62    }
63
64//    ALOGD("processTimestamp() - mMarkerFramePosition = %lld at mMarkerNanoTime %llu",
65//         (long long)mMarkerFramePosition,
66//         (long long)mMarkerNanoTime);
67//    ALOGD("processTimestamp() - framePosition = %lld at nanoTime %llu",
68//         (long long)framePosition,
69//         (long long)nanoTime);
70
71    int64_t expectedNanosDelta = convertDeltaPositionToTime(framesDelta);
72//    ALOGD("processTimestamp() - expectedNanosDelta = %lld, nanosDelta = %llu",
73//         (long long)expectedNanosDelta,
74//         (long long)nanosDelta);
75
76//    ALOGD("processTimestamp() - mSampleRate = %d", mSampleRate);
77//    ALOGD("processTimestamp() - mState = %d", mState);
78    switch (mState) {
79    case STATE_STOPPED:
80        break;
81    case STATE_STARTING:
82        mMarkerFramePosition = framePosition;
83        mMarkerNanoTime = nanoTime;
84        mState = STATE_SYNCING;
85        break;
86    case STATE_SYNCING:
87        // This will handle a burst of rapid transfer at the beginning.
88        if (nanosDelta < expectedNanosDelta) {
89            mMarkerFramePosition = framePosition;
90            mMarkerNanoTime = nanoTime;
91        } else {
92//            ALOGD("processTimestamp() - advance to STATE_RUNNING");
93            mState = STATE_RUNNING;
94        }
95        break;
96    case STATE_RUNNING:
97        if (nanosDelta < expectedNanosDelta) {
98            // Earlier than expected timestamp.
99            // This data is probably more accurate so use it.
100            // or we may be drifting due to a slow HW clock.
101            mMarkerFramePosition = framePosition;
102            mMarkerNanoTime = nanoTime;
103//            ALOGD("processTimestamp() - STATE_RUNNING - %d < %d micros - EARLY",
104//                 (int) (nanosDelta / 1000), (int)(expectedNanosDelta / 1000));
105        } else if (nanosDelta > (expectedNanosDelta + mMaxLatenessInNanos)) {
106            // Later than expected timestamp.
107            mMarkerFramePosition = framePosition;
108            mMarkerNanoTime = nanoTime - mMaxLatenessInNanos;
109//            ALOGD("processTimestamp() - STATE_RUNNING - %d > %d + %d micros - LATE",
110//                 (int) (nanosDelta / 1000), (int)(expectedNanosDelta / 1000),
111//                 (int) (mMaxLatenessInNanos / 1000));
112        }
113        break;
114    default:
115        break;
116    }
117}
118
119void IsochronousClockModel::setSampleRate(int32_t sampleRate) {
120    mSampleRate = sampleRate;
121    update();
122}
123
124void IsochronousClockModel::setFramesPerBurst(int32_t framesPerBurst) {
125    mFramesPerBurst = framesPerBurst;
126    update();
127}
128
129void IsochronousClockModel::update() {
130    int64_t nanosLate = convertDeltaPositionToTime(mFramesPerBurst); // uses mSampleRate
131    mMaxLatenessInNanos = (nanosLate > MIN_LATENESS_NANOS) ? nanosLate : MIN_LATENESS_NANOS;
132}
133
134int64_t IsochronousClockModel::convertDeltaPositionToTime(
135        int64_t framesDelta) const {
136    return (AAUDIO_NANOS_PER_SECOND * framesDelta) / mSampleRate;
137}
138
139int64_t IsochronousClockModel::convertDeltaTimeToPosition(int64_t nanosDelta) const {
140    return (mSampleRate * nanosDelta) / AAUDIO_NANOS_PER_SECOND;
141}
142
143int64_t IsochronousClockModel::convertPositionToTime(int64_t framePosition) const {
144    if (mState == STATE_STOPPED) {
145        return mMarkerNanoTime;
146    }
147    int64_t nextBurstIndex = (framePosition + mFramesPerBurst - 1) / mFramesPerBurst;
148    int64_t nextBurstPosition = mFramesPerBurst * nextBurstIndex;
149    int64_t framesDelta = nextBurstPosition - mMarkerFramePosition;
150    int64_t nanosDelta = convertDeltaPositionToTime(framesDelta);
151    int64_t time = (int64_t) (mMarkerNanoTime + nanosDelta);
152//    ALOGD("IsochronousClockModel::convertPositionToTime: pos = %llu --> time = %llu",
153//         (unsigned long long)framePosition,
154//         (unsigned long long)time);
155    return time;
156}
157
158int64_t IsochronousClockModel::convertTimeToPosition(int64_t nanoTime) const {
159    if (mState == STATE_STOPPED) {
160        return mMarkerFramePosition;
161    }
162    int64_t nanosDelta = nanoTime - mMarkerNanoTime;
163    int64_t framesDelta = convertDeltaTimeToPosition(nanosDelta);
164    int64_t nextBurstPosition = mMarkerFramePosition + framesDelta;
165    int64_t nextBurstIndex = nextBurstPosition / mFramesPerBurst;
166    int64_t position = nextBurstIndex * mFramesPerBurst;
167//    ALOGD("IsochronousClockModel::convertTimeToPosition: time = %llu --> pos = %llu",
168//         (unsigned long long)nanoTime,
169//         (unsigned long long)position);
170//    ALOGD("IsochronousClockModel::convertTimeToPosition: framesDelta = %llu, mFramesPerBurst = %d",
171//         (long long) framesDelta, mFramesPerBurst);
172    return position;
173}
174