similar to: Granule Pos of start of page...

After trying to find out what to do when no packets complete on a page... i reread the ogg spec and found this... "A special value of -1 (in two's complement) indicates that no packets finish on this page." So i searched through a few files and it appears that the muxer doesn't do this... has this been depracated ? In all cases i can find that this happens the page has the same

> 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

Dear all I'm aware that there have been several discussions about the seeking issue and I'm sorry to bring this up again. To solve the problem with Inter-Frame garbage, a seek to the previous keyframe has to be made. The keyframe number should be extracted from the granulepos of the frame where we want to seek to. I hope I understood the theory - unfortunately a few questions have

Folks have noticed that the documentation is semi-silent about how to properly encode the granule position and interleave synchronization of keyframe-based video. The primary reasons for this: a) we at Xiph hadn't had to do it yet b) there are several easy possibilities, and the longer we had to think about it before mandating One True Spec, the better that spec would likely be. The

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 all, I'm actually learning how to use ogg, theora and vorbis. My idea is to create a small program running, that is able to concatenate ogg video+audio files. However I have some small questions. Here I will start with the first one: I read the following for seeking in ogg for a theora key-frame: ---- snipp (http://www.xiph.org/ogg/doc/ogg-multiplex.html) ---- [...]The third point

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

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

Question: is it permissible to put more than one frame packet into a page? At 30 fps, Ogg page overhead is on the order of 8 - 10 kbits/sec. At low datarates, this is going to be unacceptable. If I shove a few frames into a page, how does this affect the granulepos stuff? ___ Dan Miller (++,) Founder, On2 Technologies <p>--- >8 ---- List archives: http://www.xiph.org/archives/

Hi, I've seen several implementations of Ogg demuxing that use a zero granulepos to detect headers. However, I do not recall seeing this in the Ogg docs - is this an abuse that happens to work because Vorbis is timed by end granule, or is it a proper way to check ? Thanks

> 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, 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

Hi, I am continuing to try to debug my ogg/theora decoder. The issue seems to be that not enough packets are being pulled from the bitstream, here is some sample output from my player with some debugging comments put in: (playback began at first frame, this is from the middle of the clip) get page at 1765027 got packet frame++, skip is 0 frame decoded page processed, kframe=414 : offs=442 get

One of the issues I've consistently run into with the cortado player app is seek behavior, so I was curious to see how cortado handles video encoded with the latest ffmpeg2theora (0.26) and the new -seek-index option, so I tried converting an h.264 video: ffmpeg2theora tronlegacy-tsr1_480p.mov --seek-index This output the following advisory messages: > Allocated 372 bytes for theora

Hi all, > One problem I see with your proposed implementation is that it does not > specify how audio and video would be synchronized, since there are no > absolute time stamps for the video frames. So it is difficult to account > for > audio latency on different systems, much like when you play an AVI file. > Ideally it would be wonderful to have timestamps that could be used

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

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.

Hi, I have modified fenice(streaming server) and mplayer(media client) code to support for ogg container(vorbis+theora). Now I have to implement forward and rewind of an ogg(vorbis+theora)file by time. So I would like to do file seek to start reading the file from that position. Eg:- mplayer will send +10 secs to forward request to fenice through RTSP and fenice should read and send packets from

Hi, I have modified fenice(streaming server) and mplayer(media client) code to support for ogg container(vorbis+theora). Now I have to implement forward and rewind of an ogg(vorbis+theora)file by time. So I would like to do file seek to start reading the file from that position. Eg:- mplayer will send +10 secs to forward request to fenice through RTSP and fenice should read and send packets from

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