CdSrc
Object Hierarchy:
Description:
[ GIR ( name = "AudioCdSrc" ) ]
public class CdSrc : PushSrc, URIHandler
Provides a base class for CD digital audio (CDDA) sources, which handles things like seeking, querying, discid calculation, tags, and buffer timestamping.
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typeof (unichar2) Using GstAudioCdSrc-based
elements in applications
GstAudioCdSrc registers two Formats of its own, namely the "track" format and the "sector" format. Applications will usually only find the "track" format interesting. You can retrieve that Format for use in seek events or queries with gst_format_get_by_nick("track").
In order to query the number of tracks, for example, an application would set the CDDA source element to READY or PAUSED state and then query the the number of tracks via query_duration using the track format acquired above. Applications can query the currently playing track in the same way.
Alternatively, applications may retrieve the currently playing track and the total number of tracks from the taglist that will posted on the bus whenever the CD is opened or the currently playing track changes. The taglist will contain GST_TAG_TRACK_NUMBER and GST_TAG_TRACK_COUNT tags.
Applications playing back CD audio using playbin and cdda://n URIs should issue a seek command in track format to change between tracks, rather than setting a new cdda://n+1 URI on playbin (as setting a new URI on playbin involves closing and re-opening the CD device, which is much much slower).
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typeof (unichar2) Tags and meta-information
CDDA sources will automatically emit a number of tags, details about which can be found in the libgsttag documentation. Those tags are: CDDB_DISCID, CDDB_DISCID_FULL, MUSICBRAINZ_DISCID, MUSICBRAINZ_DISCID_FULL, among others.
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typeof (unichar2) Tracks and Table of Contents
(TOC)
Applications will be informed of the available tracks via a TOC message on the pipeline's Bus. The Toc will contain a TocEntry for each track, with information about each track. The duration for each track can be retrieved via the DURATION tag from each entry's tag list, or calculated via get_start_stop_times. The track entries in the TOC will be sorted by track number.