From 420b49905b3c60749067341ea9cae7df97145bd5 Mon Sep 17 00:00:00 2001 From: "Ronald S. Bultje" Date: Wed, 28 Jan 2004 15:13:10 +0000 Subject: [PATCH] docs/pwg/advanced_tagging.xml: Half-assed commit so Thomas can re-arrange document IDs here to be consistent, too. Original commit message from CVS: 2004-01-28 Ronald Bultje * docs/pwg/advanced_tagging.xml: Half-assed commit so Thomas can re-arrange document IDs here to be consistent, too. --- ChangeLog | 6 ++++++ docs/pwg/advanced-tagging.xml | 49 ++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 54 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index 23a765f..b8d7d1a 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2004-01-28 Ronald Bultje + + * docs/pwg/advanced_tagging.xml: + Half-assed commit so Thomas can re-arrange document IDs here to be + consistent, too. + 2004-01-28 Thomas Vander Stichele * docs/manual/autoplugging.xml: diff --git a/docs/pwg/advanced-tagging.xml b/docs/pwg/advanced-tagging.xml index 4b239f9..e096f5c 100644 --- a/docs/pwg/advanced-tagging.xml +++ b/docs/pwg/advanced-tagging.xml @@ -1,6 +1,53 @@ Tagging (Metadata and Streaminfo) - WRITEME + Tags are pieces of information stored in a stream that are not the content + itself, butthey rather describe the content. Most + media container formats support tagging in one way or another. Ogg uses + VorbisComment for this, MP3 uses ID3, AVI and WAV use RIFF's INFO list + chunk, etc. GStreamer provides a general way for elements to read tags from + the stream and expose this to the user. The tags (at least the metadata) + will be part of the stream inside the pipeline. The consequence of this is + that transcoding of files from one format to another will automatically + preserve tags, as long as the input and output format elements both support + tagging. + + Tags are separated in two categories in GStreamer, even though applications + won't notice anything of this. The first are called metadata, + the second are called streaminfo. Metadata are tags + that describe the non-technical parts of stream content. They can be + changed without needing to re-encode the stream completely. Examples are + author, title or album. The + container format might still need to be re-written for the tags to fit in, + though. Streaminfo, on the other hand, are tags that describe the stream + contents technically. To change them, the stream needs to be re-encoded. + Examples are codec or bitrate. Note that some + container formats (like ID3) store various streaminfo tags as metadata in + the file container, which means that they can be changed so that they don't + match the content in the file anymore. Still, they are called metadata + because technically, they can be changed without + re-encoding the whole stream, even though that makes them invalid. Files + with such metadata tags will have the same tag twice: once as metadata, + once as streaminfo. + + + A tag reading element is called TagGetter in + &GStreamer;. A tag writer is called TagSetter. An + element supporting both can be used in a tag editor for quick tag changing. + + + + Reading Tags from Streams + + WRITEME + + + + + Writing Tags to Streams + + WRITEME + + -- 2.7.4