Atamido
9th January 2003, 09:16
Okay, I needed to post this, but it was off topic where I was typing it. Feel free to comment.
USF (http://www.corecodec.com/modules.php?op=modload&name=phpBB2&file=viewforum&f=12) was first developed by a member of "The Core Media Player" team to be used as a flexible subtitling format. It used XML as the core, so it offered quite a bit of flexibility in a standardized format. Once it was seen what was possible to do with this format, a cry went out to make it general purpose, and not just to be used with TCMP. Because the TCMP and MCF/Matroska teams work closely together, it didn't take long to decide that this subtitle format would probably be better than what had already been planned. This was happenning around the same time that it was being decided to make MCF (http://mcf.sourceforge.net) more extendable (ala Matroska (http://www.matroska.org)) by using a binary XML type of format. Because storing the text in a media file isn't very space efficient, it was decided to use the same type of binary XML as Matroska for storing USF in media containers. No version of binary XML was well suited for this task, so EBML (http://sourceforge.net/projects/ebml/) was founded to define a spec for a version of binary XML.
The idea is that subtitles/karaoke/whatever is stored in the XML format. When the person wants it in the video, they mux it in with a muxer that translates it to EBML. And, because it is a timecode based stream, it is possible at this point to edit portions out of the movie, or add portions in, and the subtitles don't loose synch.
The acronym USF stands for Universal Subtitle Format, so it is designed to be able to be used in different types of containers, including OGG and Matroska.
Extraneous information:
Matroska (http://www.matroska.org) MCF (http://mcf.sourceforge.net) OGG (http://www.ogg.org/) EBML (http://sourceforge.net/projects/ebml/) are all opensource projects and can be contributed and used by anyone.
Because Matroska and USF will both use EBML, the same EBML parser code can be used on both of these.
Xiph.org should be defining how video, audio, and subtitles are stored in OGG soon because of the acuisition of OGM.
USF will not be required to be converted to EBML, it is just better because of video editing and convenience.
USF (http://www.corecodec.com/modules.php?op=modload&name=phpBB2&file=viewforum&f=12) was first developed by a member of "The Core Media Player" team to be used as a flexible subtitling format. It used XML as the core, so it offered quite a bit of flexibility in a standardized format. Once it was seen what was possible to do with this format, a cry went out to make it general purpose, and not just to be used with TCMP. Because the TCMP and MCF/Matroska teams work closely together, it didn't take long to decide that this subtitle format would probably be better than what had already been planned. This was happenning around the same time that it was being decided to make MCF (http://mcf.sourceforge.net) more extendable (ala Matroska (http://www.matroska.org)) by using a binary XML type of format. Because storing the text in a media file isn't very space efficient, it was decided to use the same type of binary XML as Matroska for storing USF in media containers. No version of binary XML was well suited for this task, so EBML (http://sourceforge.net/projects/ebml/) was founded to define a spec for a version of binary XML.
The idea is that subtitles/karaoke/whatever is stored in the XML format. When the person wants it in the video, they mux it in with a muxer that translates it to EBML. And, because it is a timecode based stream, it is possible at this point to edit portions out of the movie, or add portions in, and the subtitles don't loose synch.
The acronym USF stands for Universal Subtitle Format, so it is designed to be able to be used in different types of containers, including OGG and Matroska.
Extraneous information:
Matroska (http://www.matroska.org) MCF (http://mcf.sourceforge.net) OGG (http://www.ogg.org/) EBML (http://sourceforge.net/projects/ebml/) are all opensource projects and can be contributed and used by anyone.
Because Matroska and USF will both use EBML, the same EBML parser code can be used on both of these.
Xiph.org should be defining how video, audio, and subtitles are stored in OGG soon because of the acuisition of OGM.
USF will not be required to be converted to EBML, it is just better because of video editing and convenience.