Hi David, David, continuing the discussion from November, about chopping Ogg Dirac files:
2008/12/5 David Schleef <[email protected]>: > On Fri, Dec 05, 2008 at 06:34:41AM +0900, Conrad Parker wrote: >> So the last remaining tool to check is oggz-chop. I at first assumed it >> would not work with Dirac's granulepos, but it seems to do something >> vaguely useful: >> >> 00:00:06.923: serialno 1763535876, granulepos >> (pt:334,dt:332,dist:51,delay:2), packetno 2: 1.685 kB > > The first picture should have a dist of 0, indicating that it's a place > you can start decoding from. ok, I implemented this method in r3879: https://trac.annodex.net/changeset/3879 Please test :-) > If you chopped an open GOP, you might get a few pictures after that > which depend on earlier pictures, but they have presentation times > before the key frame. They will be ignored by the decoder. > ok, that's good; it seems this method should be correct, ie. it ensures to provide at least all data required to present frames from the chop start time. 2008/12/6 David Flynn <[email protected]>: > On 2008-12-04, Conrad Parker <[email protected]> wrote: >> - if not, how should the packets that a given packet depends on be >> determined, >> ie. how to determine reference frames? Is it possible to do so using only >> the >> granulepos encoding? > > If you find the picture at time (t), inspect the dist value in the > decoded granule_position. then something equivalent to searching > for a granule_position matching: > candidate_granpos >> 32 == (GP64 >> 32) - dist > > NB, dist / (field_coding+1) should be the number of packets to go > backwards by. > > NB, don't keep repeating until you find dist=0, just do it once. Is this suggesting a more efficient method (ie. will it include fewer unnecessary pages at the start of the stream, compared to including all pages from the most recent with dist=0?) Conrad. ------------------------------------------------------------------------------ Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are powering Web 2.0 with engaging, cross-platform capabilities. Quickly and easily build your RIAs with Flex Builder, the Eclipse(TM)based development software that enables intelligent coding and step-through debugging. Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com _______________________________________________ Schrodinger-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/schrodinger-devel
