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/*
* Copyright 2015 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
package org.appspot.apprtc;
import android.widget.SeekBar;
import android.widget.TextView;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import org.webrtc.CameraEnumerationAndroid.CaptureFormat;
/**
* Control capture format based on a seekbar listener.
*/
public class CaptureQualityController implements SeekBar.OnSeekBarChangeListener {
private final List<CaptureFormat> formats =
Arrays.asList(new CaptureFormat(1280, 720, 0, 30000), new CaptureFormat(960, 540, 0, 30000),
new CaptureFormat(640, 480, 0, 30000), new CaptureFormat(480, 360, 0, 30000),
new CaptureFormat(320, 240, 0, 30000), new CaptureFormat(256, 144, 0, 30000));
// Prioritize framerate below this threshold and resolution above the threshold.
private static final int FRAMERATE_THRESHOLD = 15;
private TextView captureFormatText;
private CallFragment.OnCallEvents callEvents;
private int width;
private int height;
private int framerate;
private double targetBandwidth;
public CaptureQualityController(
TextView captureFormatText, CallFragment.OnCallEvents callEvents) {
this.captureFormatText = captureFormatText;
this.callEvents = callEvents;
}
private final Comparator<CaptureFormat> compareFormats = new Comparator<CaptureFormat>() {
@Override
public int compare(CaptureFormat first, CaptureFormat second) {
int firstFps = calculateFramerate(targetBandwidth, first);
int secondFps = calculateFramerate(targetBandwidth, second);
if ((firstFps >= FRAMERATE_THRESHOLD && secondFps >= FRAMERATE_THRESHOLD)
|| firstFps == secondFps) {
// Compare resolution.
return first.width * first.height - second.width * second.height;
} else {
// Compare fps.
return firstFps - secondFps;
}
}
};
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
if (progress == 0) {
width = 0;
height = 0;
framerate = 0;
captureFormatText.setText(R.string.muted);
return;
}
// Extract max bandwidth (in millipixels / second).
long maxCaptureBandwidth = java.lang.Long.MIN_VALUE;
for (CaptureFormat format : formats) {
maxCaptureBandwidth =
Math.max(maxCaptureBandwidth, (long) format.width * format.height * format.framerate.max);
}
// Fraction between 0 and 1.
double bandwidthFraction = (double) progress / 100.0;
// Make a log-scale transformation, still between 0 and 1.
final double kExpConstant = 3.0;
bandwidthFraction =
(Math.exp(kExpConstant * bandwidthFraction) - 1) / (Math.exp(kExpConstant) - 1);
targetBandwidth = bandwidthFraction * maxCaptureBandwidth;
// Choose the best format given a target bandwidth.
final CaptureFormat bestFormat = Collections.max(formats, compareFormats);
width = bestFormat.width;
height = bestFormat.height;
framerate = calculateFramerate(targetBandwidth, bestFormat);
captureFormatText.setText(
String.format(captureFormatText.getContext().getString(R.string.format_description), width,
height, framerate));
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
callEvents.onCaptureFormatChange(width, height, framerate);
}
// Return the highest frame rate possible based on bandwidth and format.
private int calculateFramerate(double bandwidth, CaptureFormat format) {
return (int) Math.round(
Math.min(format.framerate.max, (int) Math.round(bandwidth / (format.width * format.height)))
/ 1000.0);
}
}