我有播放HLS视频的ExoPlayer，我需要让用户能够改变视频质量（自动/ 1080/720/480）。
我发现使用AdaptiveTrackSelection.Factory可以确定质量，但它会一直存在，直到对象被杀死。
我也尝试使用MappingTrackSelector，我知道我的视频有4首曲目，但我没有得到如何手动选择任何曲目。这个选择会使它有效吗？
感谢任何想法。
MappingTrackSelector.MappedTrackInfo trackInfo = mDefaultTrackSelector.getCurrentMappedTrackInfo();
mDefaultTrackSelector.selectTracks(
//应该去哪里？
, trackInfo.getTrackGroups(4));
答案 0 :(得分：2)
关于这个帖子：https://github.com/google/ExoPlayer/issues/2250，我设法在播放前一个播放器时改变了外部播放器的视频质量，因此它不会立即进入缓冲状态。
所以我有下一堂课：
public enum HLSQuality {
Auto, Quality1080, Quality720, Quality480, NoValue
}
class HLSUtil {
private HLSUtil() {
}
@NonNull
static HLSQuality getQuality(@NonNull Format format) {
switch (format.height) {
case 1080: {
return HLSQuality.Quality1080;
}
case 720: {
return HLSQuality.Quality720;
}
case 480:
case 486: {
return HLSQuality.Quality480;
}
default: {
return HLSQuality.NoValue;
}
}
}
static boolean isQualityPlayable(@NonNull Format format) {
return format.height <= 1080;
}
}
public class ClassAdaptiveTrackSelection extends BaseTrackSelection {
public static final class Factory implements TrackSelection.Factory {
private final BandwidthMeter bandwidthMeter;
private final int maxInitialBitrate = 2000000;
private final int minDurationForQualityIncreaseMs = 10000;
private final int maxDurationForQualityDecreaseMs = 25000;
private final int minDurationToRetainAfterDiscardMs = 25000;
private final float bandwidthFraction = 0.75f;
private final float bufferedFractionToLiveEdgeForQualityIncrease = 0.75f;
public Factory(BandwidthMeter bandwidthMeter) {
this.bandwidthMeter = bandwidthMeter;
}
@Override
public ClassAdaptiveTrackSelection createTrackSelection(TrackGroup group, int... tracks) {
Log.d(ClassAdaptiveTrackSelection.class.getSimpleName(), " Video player quality reset to Auto");
sHLSQuality = HLSQuality.Auto;
return new ClassAdaptiveTrackSelection(
group,
tracks,
bandwidthMeter,
maxInitialBitrate,
minDurationForQualityIncreaseMs,
maxDurationForQualityDecreaseMs,
minDurationToRetainAfterDiscardMs,
bandwidthFraction,
bufferedFractionToLiveEdgeForQualityIncrease
);
}
}
private static HLSQuality sHLSQuality = HLSQuality.Auto;
private final BandwidthMeter bandwidthMeter;
private final int maxInitialBitrate;
private final long minDurationForQualityIncreaseUs;
private final long maxDurationForQualityDecreaseUs;
private final long minDurationToRetainAfterDiscardUs;
private final float bandwidthFraction;
private final float bufferedFractionToLiveEdgeForQualityIncrease;
private int selectedIndex;
private int reason;
private ClassAdaptiveTrackSelection(TrackGroup group,
int[] tracks,
BandwidthMeter bandwidthMeter,
int maxInitialBitrate,
long minDurationForQualityIncreaseMs,
long maxDurationForQualityDecreaseMs,
long minDurationToRetainAfterDiscardMs,
float bandwidthFraction,
float bufferedFractionToLiveEdgeForQualityIncrease) {
super(group, tracks);
this.bandwidthMeter = bandwidthMeter;
this.maxInitialBitrate = maxInitialBitrate;
this.minDurationForQualityIncreaseUs = minDurationForQualityIncreaseMs * 1000L;
this.maxDurationForQualityDecreaseUs = maxDurationForQualityDecreaseMs * 1000L;
this.minDurationToRetainAfterDiscardUs = minDurationToRetainAfterDiscardMs * 1000L;
this.bandwidthFraction = bandwidthFraction;
this.bufferedFractionToLiveEdgeForQualityIncrease = bufferedFractionToLiveEdgeForQualityIncrease;
selectedIndex = determineIdealSelectedIndex(Long.MIN_VALUE);
reason = C.SELECTION_REASON_INITIAL;
}
@Override
public void updateSelectedTrack(long playbackPositionUs, long bufferedDurationUs, long availableDurationUs) {
long nowMs = SystemClock.elapsedRealtime();
// Stash the current selection, then make a new one.
int currentSelectedIndex = selectedIndex;
selectedIndex = determineIdealSelectedIndex(nowMs);
if (selectedIndex == currentSelectedIndex) {
return;
}
if (!isBlacklisted(currentSelectedIndex, nowMs)) {
// Revert back to the current selection if conditions are not suitable for switching.
Format currentFormat = getFormat(currentSelectedIndex);
Format selectedFormat = getFormat(selectedIndex);
if (selectedFormat.bitrate > currentFormat.bitrate
&& bufferedDurationUs < minDurationForQualityIncreaseUs(availableDurationUs)) {
// The selected track is a higher quality, but we have insufficient buffer to safely switch
// up. Defer switching up for now.
selectedIndex = currentSelectedIndex;
} else if (selectedFormat.bitrate < currentFormat.bitrate
&& bufferedDurationUs >= maxDurationForQualityDecreaseUs) {
// The selected track is a lower quality, but we have sufficient buffer to defer switching
// down for now.
selectedIndex = currentSelectedIndex;
}
}
// If we adapted, update the trigger.
if (selectedIndex != currentSelectedIndex) {
reason = C.SELECTION_REASON_ADAPTIVE;
}
}
@Override
public int getSelectedIndex() {
return selectedIndex;
}
@Override
public int getSelectionReason() {
return reason;
}
@Override
public Object getSelectionData() {
return null;
}
@Override
public int evaluateQueueSize(long playbackPositionUs, List<? extends MediaChunk> queue) {
if (queue.isEmpty()) {
return 0;
}
int queueSize = queue.size();
long bufferedDurationUs = queue.get(queueSize - 1).endTimeUs - playbackPositionUs;
if (bufferedDurationUs < minDurationToRetainAfterDiscardUs) {
return queueSize;
}
int idealSelectedIndex = determineIdealSelectedIndex(SystemClock.elapsedRealtime());
Format idealFormat = getFormat(idealSelectedIndex);
// If the chunks contain video, discard from the first SD chunk beyond
// minDurationToRetainAfterDiscardUs whose resolution and bitrate are both lower than the ideal
// track.
for (int i = 0; i < queueSize; i++) {
MediaChunk chunk = queue.get(i);
Format format = chunk.trackFormat;
long durationBeforeThisChunkUs = chunk.startTimeUs - playbackPositionUs;
if (durationBeforeThisChunkUs >= minDurationToRetainAfterDiscardUs
&& format.bitrate < idealFormat.bitrate
&& format.height != Format.NO_VALUE && format.height < 720
&& format.width != Format.NO_VALUE && format.width < 1280
&& format.height < idealFormat.height) {
return i;
}
}
return queueSize;
}
private int determineIdealSelectedIndex(long nowMs) {
if (sHLSQuality != HLSQuality.Auto) {
Log.d(ClassAdaptiveTrackSelection.class.getSimpleName(), " Video player quality seeking for " + String.valueOf(sHLSQuality));
for (int i = 0; i < length; i++) {
Format format = getFormat(i);
if (HLSUtil.getQuality(format) == sHLSQuality) {
Log.d(ClassAdaptiveTrackSelection.class.getSimpleName(), " Video player quality set to " + String.valueOf(sHLSQuality));
return i;
}
}
}
Log.d(ClassAdaptiveTrackSelection.class.getSimpleName(), " Video player quality seeking for auto quality " + String.valueOf(sHLSQuality));
long bitrateEstimate = bandwidthMeter.getBitrateEstimate();
long effectiveBitrate = bitrateEstimate == BandwidthMeter.NO_ESTIMATE
? maxInitialBitrate : (long) (bitrateEstimate * bandwidthFraction);
int lowestBitrateNonBlacklistedIndex = 0;
for (int i = 0; i < length; i++) {
if (nowMs == Long.MIN_VALUE || !isBlacklisted(i, nowMs)) {
Format format = getFormat(i);
if (format.bitrate <= effectiveBitrate && HLSUtil.isQualityPlayable(format)) {
Log.d(ClassAdaptiveTrackSelection.class.getSimpleName(), " Video player quality auto quality found " + String.valueOf(sHLSQuality));
return i;
} else {
lowestBitrateNonBlacklistedIndex = i;
}
}
}
return lowestBitrateNonBlacklistedIndex;
}
private long minDurationForQualityIncreaseUs(long availableDurationUs) {
boolean isAvailableDurationTooShort = availableDurationUs != C.TIME_UNSET
&& availableDurationUs <= minDurationForQualityIncreaseUs;
return isAvailableDurationTooShort
? (long) (availableDurationUs * bufferedFractionToLiveEdgeForQualityIncrease)
: minDurationForQualityIncreaseUs;
}
static void setHLSQuality(HLSQuality HLSQuality) {
sHLSQuality = HLSQuality;
}
}
希望它有所帮助。