Add POST_LIVE_STREAM and POST_LIVE_AUDIO_STREAM stream types

This allows the extractor to determine if a content is an ended audio or video livestream.

extractor/src/main/java/org/schabi/newpipe/extractor/stream/StreamType.java

@@ -1,10 +1,115 @@
 package org.schabi.newpipe.extractor.stream;
 
+/**
+ * An enum representing the stream types of stream contents returned by the extractor.
+ */
 public enum StreamType {
-    NONE,   // placeholder to check if stream type was checked or not
+
+    /**
+     * Placeholder to check if the stream type of stream content was checked or not.
+     *
+     * <p>
+     * It doesn't make sense to use this enum constant outside of the extractor as it will never be
+     * returned by an {@link org.schabi.newpipe.extractor.Extractor extractor} and is only used
+     * internally.
+     * </p>
+     */
+    NONE,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is a video.
+     *
+     * <p>
+     * Note that contents <strong>can contain audio streams</strong> even if they also contain
+     * video streams (video-only or video with audio, depending of the stream/the content/the
+     * service).
+     * </p>
+     */
     VIDEO_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is an audio.
+     *
+     * <p>
+     * Note that contents returned as audio streams should not return video streams.
+     * </p>
+     *
+     * <p>
+     * So, in order to prevent unexpected behaviors, stream extractors which are returning this
+     * stream type for a content should ensure that no video stream is returned for this content.
+     * </p>
+     */
     AUDIO_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is a video.
+     *
+     * <p>
+     * Note that contents <strong>can contain audio live streams</strong> even if they also contain
+     * live video streams (video-only or video with audio, depending of the stream/the content/the
+     * service).
+     * </p>
+     */
     LIVE_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is a live audio content.
+     *
+     * <p>
+     * Note that contents returned as live audio streams should not return live video streams.
+     * </p>
+     *
+     * <p>
+     * So, in order to prevent unexpected behaviors, stream extractors which are returning this
+     * stream type for a content should ensure that no live video stream is returned for this
+     * content.
+     * </p>
+     */
     AUDIO_LIVE_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is a video content of an
+     * ended live video stream.
+     *
+     * <p>
+     * Note that most of ended live video (or audio) contents may be extracted as
+     * {@link #VIDEO_STREAM regular video contents} (or
+     * {@link #AUDIO_STREAM regular audio contents}) later, because the service may encode them
+     * again later as normal video/audio streams. That's the case for example on YouTube.
+     * </p>
+     *
+     * <p>
+     * Note that contents <strong>can contain post-live audio streams</strong> even if they also
+     * contain post-live video streams (video-only or video with audio, depending of the stream/the
+     * content/the service).
+     * </p>
+     */
+    POST_LIVE_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is an audio content of an
+     * ended live audio stream.
+     *
+     * <p>
+     * Note that most of ended live audio streams extracted with this value are processed as
+     * {@link #AUDIO_STREAM regular audio streams} later, because the service may encode them
+     * again later.
+     * </p>
+     *
+     * <p>
+     * Contents returned as post-live audio streams should not return post-live video streams.
+     * </p>
+     *
+     * <p>
+     * So, in order to prevent unexpected behaviors, stream extractors which are returning this
+     * stream type for a content should ensure that no post-live video stream is returned for this
+     * content.
+     * </p>
+     */
+    POST_LIVE_AUDIO_STREAM,
+
+    /**
+     * Enum constant to indicate that the stream type of stream content is a file.
+     */
     FILE
 }