Stream metadata

A StreamExtractor returns far more than playable formats. Almost all of it is optional with a safe default, so a service fills in what it can and the app shows what it has.

The surface

Beyond getAudioStreams / getVideoStreams / getVideoOnlyStreams, a StreamExtractor exposes (return types abbreviated):

Description getDescription();
long getLength();  long getTimeStamp();          // duration, and a t= deep-link offset
long getViewCount();  long getLikeCount();  long getDislikeCount();
String getUploaderName() / Url() / AvatarUrl();  long getUploaderSubscriberCount();  boolean isUploaderVerified();
String getSubChannelName() / Url();              // e.g. a topic / sub-channel
String getTextualUploadDate();  DateWrapper getUploadDate();
List<Image> getThumbnails();
List<SubtitlesStream> getSubtitlesDefault();  List<SubtitlesStream> getSubtitles(MediaFormat);
List<StreamSegment> getStreamSegments();         // chapters
List<MetaInfo> getMetaInfo();                    // info boxes
List<Frameset> getFrames();                      // storyboard preview thumbnails
StreamInfoItemsCollector getRelatedStreams();
StreamType getStreamType();  Privacy getPrivacy();   // PUBLIC, UNLISTED, PRIVATE, INTERNAL, OTHER
String getCategory();  String getLicence();  List<String> getTags();  String getHost();

StreamInfo.getInfo runs these inside extractStreams / extractOptionalData, each wrapped so a missing one becomes a collected error rather than a failure (see Extraction flow).

Description: typed text

A Description is content plus a type, so the app knows how to render it:

class Description { String getContent();  int getType(); }   // HTML = 1, MARKDOWN = 2, PLAIN_TEXT = 3
Description.EMPTY_DESCRIPTION   // the default

Chapters: StreamSegment

A StreamSegment is one chapter on the timeline:

String getTitle();  int getStartTimeSeconds();
String getChannelName();   // optional, when a chapter credits a creator
String getUrl();           // optional deep link
String getPreviewUrl();

Subtitles

SubtitlesStream extends Stream (so it carries a DeliveryMethod and content/URL) and adds:

String getLanguageTag();  Locale getLocale();  String getDisplayLanguageName();
boolean isAutoGenerated();  String getExtension();   // from the MediaFormat: VTT, TTML, SRT, ...

Preview frames: Frameset

A Frameset is a storyboard sprite sheet for scrubbing previews:

List<String> getUrls();  int getFrameWidth();  int getFrameHeight();
int getTotalCount();  int getDurationPerFrame();
int[] getFrameBoundsAt(long positionMs);   // -> [urlIndex, left, top, right, bottom]

getFrameBoundsAt maps a playback position to the exact crop rectangle inside the right sprite image, which is what the seek-preview thumbnail draws.

MetaInfo: info boxes

MetaInfo is the contextual box services attach to some videos (a Wikipedia, health, or election notice, for example):

String getTitle();  Description getContent();  List<URL> getUrls();  List<String> getUrlTexts();