- From: Raphaël Troncy <Raphael.Troncy@cwi.nl>
- Date: Tue, 14 Oct 2008 14:07:25 +0200
- To: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
- CC: Yves Lafon <ylafon@w3.org>, Jack Jansen <Jack.Jansen@cwi.nl>, Yannick Prié <yannick.prie@liris.cnrs.fr>, Media Fragment <public-media-fragment@w3.org>
Dear Silvia, [...] > The biggest problem here being that > time is inherently inaccurate (for being essentially a floating point > number) while bytes are accurate (for being an integer). So, if you > are asking for times 1:23-1:45.32 and then 1:45.33-1:56 in two > fragment requests, it is somewhat impossible for the Web proxy to know > whether that is enough data to compose 1:23-1:56 or whether it has > accidentally missed or duplicated a few dozen bytes because they fell > into the gap between the two segments because the time resolution > cannot be made completely accurate for media resources. I (and others) did propose a while ago an internal representation of time using the least common multiple between the usual sound sample rate (96000 and sub-multiple or 44100 and sub-multiple) and video frame rate (30, 25, 24), that is 14112000. This integer defines then an universal common sample rate (i.e. 14112000 corresponds to 1 second) and any temporal point in an audio-visual content will be represented as an integer on this temporal basis. You can see the details in the paper: Raphaël Troncy, Jean Carrive, Steffen Lalande and Jean-Philippe Poli. "A Motivating Scenario for Designing an Extensible Audio-Visual Description Language". In International Workshop on Multidisciplinary Image, Video, and Audio Retrieval and Mining (CoRIMedia), Sherbrooke, Canada, October 25-26, 2004. http://www.cwi.nl/~troncy/Publications/Troncy-corimedia04.pdf Does that help to solve the problem? Cheers. Raphaël -- Raphaël Troncy CWI (Centre for Mathematics and Computer Science), Kruislaan 413, 1098 SJ Amsterdam, The Netherlands e-mail: raphael.troncy@cwi.nl & raphael.troncy@gmail.com Tel: +31 (0)20 - 592 4093 Fax: +31 (0)20 - 592 4312 Web: http://www.cwi.nl/~troncy/
Received on Tuesday, 14 October 2008 12:08:15 UTC