similar to: Zero granule pos

> No particular answers, but I can at least point out that the way > things were designed for CMML was to work with the existing Ogg > seeking algorithm. The idea is that a generic seeking routine can work > on any Ogg file, as long as it knows the granulepos->time mapping for > the logical bitstreams in the file. That's why all the > timestamp-related info is crammed into

Hi, I have a question about seeking. In fact, it's more or less a kind of rambling and thinking aloud, circling around a question. I've been wondering how to deal with seeking in a stream, and what to do when seeking in the middle of a set of active events (eg, when several bits of text are supposed to be shown, but you seek after the time when they are first shown, and before the time

David Flynn has proposed a new Ogg Dirac mapping. The draft is here: http://davidf.woaf.net/dirac-mapping-ogg.pdf This is a much bigger break from other codecs than my draft (at http://wiki.xiph.org/index.php/OggDirac). We talked a bit about it on IRC today. Below is my summary; hopefully David can correct anything I got wrong or misleading. Comments? There are two main differences

> The advantage of storing this in the granulepos field itself, like > theora and CMML do, is that the seek code may already understand how > to handle the back pointer. Right now everything assumes the mapping > is from 'initialized decoder' + 'granulepos from page header' => > timestamp, or in the case of theora and CMML => 'timestamp' + 'last

Hi, sorry, there is a bug in the CMML spec and wiki page ... I discussed this with Silvia earlier this week but haven't gotten around to correcting it yet. CMML granulepos is much like theora's; the previous granule is stored in the higher bits, and the delta since then is stored in the lower bits. The current timestamp is the sum of the two. This is the behavior of the implementations

Ups! Maybe it's time somebody corrected that statement then - the wiki seems the right place to put the correct algorithm, IMHO. Cheers, Silvia. On Feb 13, 2008 10:06 AM, Ralph Giles <ralph.giles@artifex.com> wrote: > > On 12-Feb-08, at 2:57 PM, Ralph Giles wrote: > > > http://wiki.xiph.org/index.php/GranulePosAndSeeking > > I'm not sure it's helpful to

Hi, do you still think you need all this, if you are allowed to have equal granulepos on subsequent pages? Conrad. On 18/02/2008, ogg.k.ogg.k@googlemail.com <ogg.k.ogg.k@googlemail.com> wrote: > Hi, > > I've now got another way of encoding granule (oh, not *again*, I hear > you cry). I believe it's an improvement over the existing "generic" > method, so

On 10 May 2010 23:20, Chris Pearce <chris at pearce.org.nz> wrote: > The granulepos radix was something that Conrad and Ralph were talking about > at FOMS2010. I don't know how it's supposed to be used, or why we need it. > It was supposed to be needed for Dirac? Maybe Ralph or Conrad can remember? > If not, we should remove it. There's no point in adding a poorly

2008/11/21 David Flynn <davidf+nntp at woaf.net>: > On 2008-11-21, Conrad Parker <conrad at metadecks.org> wrote: >> 2008/11/15 David Flynn <davidf+nntp at woaf.net>: >>> On 2008-11-14, Conrad Parker <conrad at metadecks.org> wrote: >>>> It seems oggz chop, merge and sort will need some attention to deal >>>> with the Dirac

On 15-Feb-08, at 6:44 AM, ogg.k.ogg.k@googlemail.com wrote: > Well, it doesn't quite work because the second part of the gpos is > an offset, > rather than absolute, and the precision we shed on one, we need to > recover > on the other one, to keep the ability to timestamp events at the > correct > granularity. It would have worked if the second part was absolute

> It is more complex, because the granulepos is available at the page > level. Ah. Good point, I always forget about the partial page problem :( I conveniently flush pages after each data packet in my case (due to unknown/arbitrary latency), so I tend to forget easily about those. > We've generally designed the seeking algorithm so it can be > implemented without looking inside

> There are a usually lot more data packets than header packets, so > having an internal length there hurts your bitrate a lot more. Of > course, it may not be significant for an uncompressed text codec. If muxed with a video, it's insignificant (well, for my test cases). > With codecs using the 'count of decodable samples' rule to calculate > their granulepos, the

OK... i've come across a problem trying to get the granule pos of the start of the page... it's not so crucial with single stream ogg files... but now that i have theora+vorbis in a file, i'm finding that when i seek to a position, i have no way to determine the relative offsets of the different streams at the new seek point and hence the av is out of sync. So given a page, is it

Since we've been debating the merits of start or end timestamping... i'm curious why the page doesn't have both stamps ? That would solve the problems for all parties wouldn't it ? It's not like the overhead is huge... less than 0.1%... so on the average audio file thats 5 megs.... it's a 5k increase, which pretty much insignificant. Even on a 1gig video file it's

I have a technical question about the vorbis granule position, but I would like to put the question into context. When a ogg vorbis stream is ripped using wget, fetch, or streamripper under Linux or FreeBSD, the resulting file has problems both with granule position and with a missing EOS. I think I can figure out how to add an EOS, but is there a way to determine the granule position in a stream

I'm hoping this is a new proposal, and not a rehash of something that's already been discussed and shot down. Without logs of the recent IRC discussion there's no way for me to know without asking. When I suggested it in #theora earlier derf_ or AndrewBachmann said that it had already been discussed, so I'm under the belief that this is a new idea. <p>Ok so we've

dear list, i am trying to write a small program which reads an ogg file and writes it to another ogg file (and changes serial number, granulepos etc on the fly). reading the ogg file is ok (ogg_sync_pageout, ogg_stream_pagein, ogg_stream_packetout). but writing the file doesn't work - the granulepos and page structures don't match with the original file. here's what i am doing.

After some more thought on this, I'm trying to work out whether the back link offset needs precision. Semantically, the only need we have for this is to be able to seek back to a point before the start of the earliest event still active at the time of the original seek. As far as I know, and please correct me if I'm wrong, nothing in Ogg mandates that this backlink actually resolves to a

On 12-Feb-08, at 2:54 PM, Silvia Pfeiffer wrote: > I've added Monty's email to the wiki at http://wiki.xiph.org/ > index.php/GranulePosAndSeeking , but I was unable to edit the wiki > entry page and add a "Granulepos and Seeking" link under the > "developer resources" section. Maybe somebody with more rights on > the wiki could add this. I'm

On Sat, 2006-07-15 at 14:35 -0700, Ralph Giles wrote: > On Sat, Jul 15, 2006 at 02:17:22PM -0500, Joe Wreschnig wrote: > > > I'm working on support for tagging Speex files for Mutagen[0] and part > > of the specification at [1] is confusing me. It says the first page > > should have granulepos 0 and packetno 0. Does this really mean page > > sequence number 0,