similar to: spare bits in the theora keyframe header

Derf's from-scratch alternate implementation of the theora codec is now publicly available from our subversion repository. http://svn.xiph.org/experimental/derf/theora-exp/ This exciting new codebase promises superiour performance, and the encoder is capable of higher quality output than the current represenation, taking advantage of the bitstream extension we've added to the

Here is a fix that prevents the encoder from spending too many bits on keyframes. The main problem is that the old code computes the target keyframe bitrate incorrectly. This causes the code that computes the Q for the frame to think that it has tons of bits to spend. It selects a high Q value for the keyframe. Since so many bits were spend on the keyframe the the inter-frames have to use a much

I've just committed an image flip for compatibility with VP3 lossless transcode. Thanks to mau and derf for verifying that this was needed. It's a little hacky on the decode side; suggestions for improvement are welcome. Since this is a bitstream change, and we're still a ways from having a complete spec (which is the gating item for beta 1 and the bitstream freeze) we're

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

I am using the directshow Theora encoder to compress a live video stream. A dump of the encoder settings is given below. The starred settings have been explicitly configured and the others are defaulted or derived values. These settings produce an even, dark (almost black) recorded result as does any recording with Keyframe Freq <= 32. Keyframe Freq >32 works perfectly. The incoming

Hi, When doing a live ogg+theora stream on our server we ran into the following problem: When a client connects we send out the theora header pages followed by the actual live stream pages. The problem is that the first ogg data page does not have the right page number (2), which causes libogg to not want to decode the first _packet_ of that page. Since that first packet happens to contain the

Hi, I havent posted to this list before, so "hi" I have been experimenting with Theora and noticed it still has the same crash bug that VP3 did. Basically, if you begin compression, and compress a blank black frame more than about twice in a row you get a Div by 0 error. I traced the fault to being in the "RegulateQ" function, and is because YUVAnalyseFrame() returns 0 for

Hi all, First of all a big thank you for your work. I would like to know what is (could be) the best (optimal in a psnr and/or subjectivity sense) maximum distance between keyframes or is theora using a good heuristic change scene detection mecanism? Does it really matter to theora as with mpeg4 part2/10? Thank you and keep up the good work -- Josh

attached patch adds support for the experimental theora branch to mplayer. you can get theora-exp from svn: svn co http://svn.xiph.org/experimental/derf/theora-exp/ The decoder here is feature-complete, up to and including all planned bitstream features for the initial Theora release. Some of these are not yet present even in the reference decoder. These include: - Support for non-VP3 style

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

Hello everybody ! I am working on a php class to enable, on the server-side, to extract useful data from Ogg theora videos. http://opensource.grisambre.net/ogg . I need to have it extract a thumbnail picture from a video (much like dailymotion or youtube). Right now, I am doing it using the ffmpeg-php extension (for picture extraction only), but the problem is that this module is available on

Hello, I'm just totally confused. In my theora streams encoded using ffmpeg2theora (but also when using my own encoder) I have packets with a granulepos of -1 so I can't identify the packet during a seeking operation correctly. I can also see those strange value when I just print the packet granulepos before sending it to the Theora decoder. I know why there are PAGES with granularpos of

Hi all, Attached is a trivial patch that speeds up encoding for key frame only streams. It skips the motion vector search which is not needed when there are never going to be any delta frames. It was made against thusnelda SVN revision 14589. Tested on Fedora 8 x64_64. -Phil -------------- next part -------------- A non-text attachment was scrubbed... Name:

Hi, So it took a little while to get here but VP3 through ffmpeg is finally starting to achieve viewable results. It partially works right now. Keyframes only. And monochrome. Oh, and the picture is upside down (something I did not realize about VP3 until I let it fly just now). Anyway, here is a picture of ffmpeg's VP3 decoder in action using xine:

Dan, In reviewing the code, derf came across the DCSearchPoints array in QuadCodeDisplayFragments(), encode.c:696. It looks like it specifies a search order for nearby coded fragments for prediction if there isn't a nearest neighbor. However, the upper search bound is defined as *0*, so the search loop (line 917) is never executed and it always falls back to the last coded fragment.

> From: Jay Sprenkle [mailto:cupycake_jay@yahoo.com] > I thought > you had to back up to the previous complete frame, > then apply the differences in the following frames > to generate a new complete frame where the splice > was to happen. Are you going to handle editing to > arbitrary frames? I believe you have to do something > analogous in theora/ogg. yup. > ---

I have almost finished integration of Theora into our videoconferencing program. Since a videoconferencing program is realtime, it is UDP-based and wraps the Theora stream in RTP (More on that later). The problem here is that most examples I could find, wraps the theora stream in ogg, and used over tcp or files. I send over UDP and clients need to be able to start in the middle of the stream.

Hello, i am member of red5 project. I am studying ways to integrate your codec into red5 and in a near future inside Flash Player. I want to figure some things about Theora codec. -> Is theora proper for live streams (i.e live transcondig webcam)? What is latency for encoding process? -> Is the format tolerant to lost frames? Thanks for the moment.

Here is a patch that fixes distortions that appear during scenes with no motion. Tbe problem was that UpdateFrame() was not being called when a MotionScore of 0 was computed. Since UpdateFrame() was not called the buffer returned by theora_encode_packetout() would be the same buffer that was output for the last frame that had a non-zero MotionScore. This is obviously incorrect behavior. I've

I'm new to the list so please excuse me if this has already been rehashed before. There seems to be something very odd about how the PP_INSTANCE::PrevFragments array is handled during keyframes. I'm not a video codec expert so I'm not entirely sure what the reason for keeping a history of blocks updated in the last few previous interframes and adding them to the blocks to be