Interface TagSetter

All Superinterfaces:
Proxy
All Known Implementing Classes:
TagSetter.TagSetter$Impl
@Generated("org.javagi.JavaGI") public interface TagSetter extends Proxy

Element interface that allows setting of media metadata.

Elements that support changing a stream's metadata will implement this interface. Examples of such elements are 'vorbisenc', 'theoraenc' and 'id3v2mux'.

If you just want to retrieve metadata in your application then all you need to do is watch for tag messages on your pipeline's bus. This interface is only for setting metadata, not for extracting it. To set tags from the application, find tagsetter elements and set tags using e.g. gst_tag_setter_merge_tags() or gst_tag_setter_add_tags(). Also consider setting the GstTagMergeMode that is used for tag events that arrive at the tagsetter element (default mode is to keep existing tags). The application should do that before the element goes to State.PAUSED.

Elements implementing the GstTagSetter interface often have to merge any tags received from upstream and the tags set by the application via the interface. This can be done like this:

GstTagMergeMode merge_mode;
const GstTagList *application_tags;
const GstTagList *event_tags;
GstTagSetter *tagsetter;
GstTagList *result;

tagsetter = GST_TAG_SETTER (element);

merge_mode = gst_tag_setter_get_tag_merge_mode (tagsetter);
application_tags = gst_tag_setter_get_tag_list (tagsetter);
event_tags = (const GstTagList *) element->event_tags;

GST_LOG_OBJECT (tagsetter, "merging tags, merge mode = %d", merge_mode);
GST_LOG_OBJECT (tagsetter, "event tags: %" GST_PTR_FORMAT, event_tags);
GST_LOG_OBJECT (tagsetter, "set   tags: %" GST_PTR_FORMAT, application_tags);

result = gst_tag_list_merge (application_tags, event_tags, merge_mode);

GST_LOG_OBJECT (tagsetter, "final tags: %" GST_PTR_FORMAT, result);

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static class 
    TagSetter.TagSetter$Impl
    The TagSetter$Impl type represents a native instance of the TagSetter interface.
    static class 
    TagSetter.TagSetterInterface
    GstTagSetterInterface interface.

  • Method Summary

    Modifier and Type
    Method
    Description
    default void
    addTags(TagMergeMode mode, String tag, Object... varargs)
    Adds the given tag / value pairs on the setter using the given merge mode.
    default void
    addTagValue(TagMergeMode mode, String tag, Value value)
    Adds the given tag / GValue pair on the setter using the given merge mode.
    default void
    addTagValues(TagMergeMode mode, String tag, Object... varargs)
    Adds the given tag / GValue pairs on the setter using the given merge mode.
    default @Nullable TagList
    getTagList()
    Returns the current list of tags the setter uses.
    default TagMergeMode
    getTagMergeMode()
    Queries the mode by which tags inside the setter are overwritten by tags from events
    static @Nullable Type
    getType()
    Get the GType of the TagSetter class.
    default void
    mergeTags(TagList list, TagMergeMode mode)
    Merges the given list into the setter's list using the given mode.
    default void
    resetTags()
    Reset the internal taglist.
    default void
    setTagMergeMode(TagMergeMode mode)
    Sets the given merge mode that is used for adding tags from events to tags specified by this interface.

    Methods inherited from interface Proxy

    handle

  • Method Details

    • getType

      static @Nullable Type getType()
      Get the GType of the TagSetter class.
      Returns:
      the GType

    • addTagValue

      default void addTagValue(TagMergeMode mode, String tag, Value value)
      Adds the given tag / GValue pair on the setter using the given merge mode.
      Parameters:
      mode - the mode to use
      tag - tag to set
      value - GValue to set for the tag

    • addTagValues

      default void addTagValues(TagMergeMode mode, String tag, Object... varargs)
      Adds the given tag / GValue pairs on the setter using the given merge mode. The list must be terminated with null.
      Parameters:
      mode - the mode to use
      tag - tag to set
      varargs - more tag / GValue pairs to set

    • addTags

      default void addTags(TagMergeMode mode, String tag, Object... varargs)
      Adds the given tag / value pairs on the setter using the given merge mode. The list must be terminated with null.
      Parameters:
      mode - the mode to use
      tag - tag to set
      varargs - more tag / value pairs to set

    • getTagList

      default @Nullable TagList getTagList()

      Returns the current list of tags the setter uses. The list should not be modified or freed.

      This function is not thread-safe.

      Returns:
      a current snapshot of the taglist used in the setter or null if none is used.

    • getTagMergeMode

      default TagMergeMode getTagMergeMode()
      Queries the mode by which tags inside the setter are overwritten by tags from events
      Returns:
      the merge mode used inside the element.

    • mergeTags

      default void mergeTags(TagList list, TagMergeMode mode)
      Merges the given list into the setter's list using the given mode.
      Parameters:
      list - a tag list to merge from
      mode - the mode to merge with

    • resetTags

      default void resetTags()
      Reset the internal taglist. Elements should call this from within the state-change handler.

    • setTagMergeMode

      default void setTagMergeMode(TagMergeMode mode)
      Sets the given merge mode that is used for adding tags from events to tags specified by this interface. The default is GST_TAG_MERGE_KEEP, which keeps the tags set with this interface and discards tags from events.
      Parameters:
      mode - The mode with which tags are added