similar to: Keyframes

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

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

a couple points before I look at this too hard: "For VP3, since you can't do a constant quality encode" what? that should not be the case. Could be a QT-specific bug. Theora at any rate is certainly capable of doing constant-quality encode. This probably explains your standard deviation complaint -- VP3 is running a rate control alg, where the other codecs are just shooting for

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 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.

Hi all, I have to compare the theora codec with MPEG and H264. I was googling and I found that the PSNR is a common used parameter. How can I do this with Theora? Thanks -- Leonardo de Paula Rosa Piga Undergraduate Computer Engineering Student LSC - IC - UNICAMP http://www.students.ic.unicamp.br/~ra033956

Hi I was surprised with size of Theora files and thought of feedback. Following 1minute duration Theora and Xvid files were made from a y4m file. The resolution is 1280x720: 1. Xvid 17MB 2. Ogg/Theora Q7 31MB 3. Ogg/Theora Q8 38MB 4. Ogg/Theora Q9 49MB 5. Ogg/Theora Q10 61MB The Xvid file was made using mencoder by 2 passes with following options:

Hello, Does anyone know the answer to this question below? (Note... they're calling the Theora codec "Ogg" below. I know technically it's not correct... but that's what some are calling it.) ---------- Forwarded message ---------- From: Enric <enric.media@gmail.com> Date: Aug 19, 2007 10:13 AM Subject: [show-in-a-box] Re: Ogg To: show-in-a-box@googlegroups.com A

Monty, Derf and I were discussing some theora bitstream improvements. He was curious about the spare bits in the keyframe header. There's a keyframe type bit which is always DCT_KEY_FRAME aka '0' and two spare bits. You took out a lot of similar extra bits in the VP3 code. Do you remember anything about the motivation for leaving this one in? Given the constant, were there plans

Hi, After a quick read of the Theora spec, I became curious about the possibility of fast quality reduction of Theora videos. The idea is to decode through the Huffman and reverse prediction steps, and then to truncate the coefficients and reencode. My questions are: * Is this a reasonable way to reduce the quality and bitrate of a stream? Will it be comparable in quality to a complete

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

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.

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/

> 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 am trying to figure out how theora timestamps map to absolute time values. This information would be needed to seek by 1 sec, 5 secs etc. I understand the granulepos is interpreted as Absolute number of key frames so far | number of frames since last key frame. E.g. 1000|1, 1000|2, ... How does this map to absolute time in millisecs since the start, I can think of the following formula: Total

Hi I'm evaluating Theora for a video communication system and would like some info as to what the following struct members (from the theora_info structure) do and what values one should pass to them: If there is some documentation somewhere that I've missed, please direct me to it. ===== Extract from theora.h ===== int quality; int quick_p; /* quick encode/decode */

Here's the problem: > 2) Encoding with rate control as in single pass "Bitrate > control" will not > lead to better quality than fixed quant (with the right value > of the fixed > quant). Ratecontrol doens't know anything about "quality". It > will try to > reach more-or-less CBR. > > But somehow this is not a fair comparison, because

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

Is anyone working on liboggplay, and if so, is there any plan to support keyframe-based seeking? I found this, but seems to me that the feature ought to be part of liboggplay: http://pearce.org.nz/2009/05/video-seeking-improvements.html Is there a more appropriate list to post to regarding liboggplay? Shayne Wissler -------------- next part -------------- An HTML attachment was scrubbed...

On 06/10/2010 09:25 PM, Chris Pearce wrote: > I looked at Benjamin's proposal, it does indeed produce much better > compression. However I decided not to use it because I felt it was too > complex. For the record, the Skeleton 4.0, as implemented by OggIndex, currently requires a multi-round iteration to produce. The encoder produces the index, then shifts the file content