similar to: Fast quality reduction transcoding

Hi. I have been working on a tool whose goal is to reduce the bit rate of theora video by decoding to DCT coefficients, reducing the entropy of the coefficients, and re-tokenizing the stream. I have successfully used the decoder source to extract the DCT coefficients for each block, and I am able to capture any and all relevant information about where the block of coefficients falls in the

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 all, Yes, it's true. A new version of rehuff, the tool that losslessly compresses Vorbis files: one that is easy to compile, and that works with newer-than-two-years-ago streams, too! On 1.0 streams, you get about 3% size reduction, and the headers get _much_ smaller (which helps for fast-start network streams). Building it should be easy (you might have to add some -I and -L for

Hi all, Yes, it's true. A new version of rehuff, the tool that losslessly compresses Vorbis files: one that is easy to compile, and that works with newer-than-two-years-ago streams, too! On 1.0 streams, you get about 3% size reduction, and the headers get _much_ smaller (which helps for fast-start network streams). Building it should be easy (you might have to add some -I and -L for

Hiya, Here is the sources to my "rehuff" program. ./rehuff in.ogg out.ogg does a lossless recoding of a vorbis stream. (It generates optimal huffman codes for the particular stream). This code is meant for developers only, until someone is kind enough to provide good build and configure support for it. I won't. And no installation help questions please. There is a little patch

Hi, is there a good concept to lower the quality of a Theora stream without completely reencoding it? For example to make a lower bitrate stream out of a higher bitrate stream on the fly on some sort of proxy server. I am thinking about something like requantization. If you think requantization is also the best (or the only) option for Theora please let me know. Kind regards, Franz

Hello ! A question to all 'Wheel-reinventers': I can build the huffmantrees by hand (on paper) but how to code it? Are there any good URLs out there? Or does the spec supply sufficient information? I tried figure out how oggdec (debugging) does this, but I couldn't get the clou. Thank you Dominik --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project

No offense, Segher, but the output quality of this thing is awful. =) I'll disregard the fact that, at least with *my* compiler, the source tarball I downloaded reduces every packet to zero bytes, which isn't terribly interesting. I decided to set the byte reduction to something constant: I started by dividing each packet's size by 2 just to see what would happen. The resulting ogg

Hello all, I've been working a little inside the Theora decoder when I found that it seems that many videos had the very same huffman tables encoded into their bitstreams (at least the ones that I could take my time to dissecate). I found that the tables are listed as TH_VP31_HUFF_CODES in the file huffenc.c. I tried to investigate a little bit more to see who was setting the bitstream

Hello, I am a computer engineering student and compression hobbyst and have recently developed a new entropy coding algorithm. It can be used to achieve compression proper of arithmetic coders at very high speeds -almost like Huffman codecs-. Since it could be of interest to you, I send it as an attachment -code and technical report-. Please, drop me a line in case you have any doubt or

I took 5 albums (Classical music) and converted them to Ogg Vorbis at "Full Bitrate" (-q10) and all 5 directories take up about 775 Megs which won't fit on a CD. So I ripped them again in WAV first (And give my friend back his CDs) but now I wanna know what quality setting should I use to fit them on 1 CD (The highest possible with total space used just under 700 Megs)

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

Hi there. I have a short .ogg with Vorbis stream @56kbps from a 44.1 16bits stereo sample, which weights exactly 135'781 bytes. Packed to ZIP, it goes down to 109'485 bytes, that's a 80% ratio ! Even worse with latest RAR3 archive, with which the file size goes to 104'349 (76%). <sceptical> I admit this sample is a bit repetitive, but I guess the probability of having the

Fredag, 11 oktober 2002, skrev du: >Rubbish. Been there, done that (multiple times). Look at rehuff, for >example; written without looking at libvorbis (nor at the spec). And you wrote that without any knowledge about the file format? Tor <p><p>=================================================================== EASY and FREE access to your email anywhere:

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

Hello, I have finally added 2 lower quality settings for the NHW codec: -l1 (-5Ko) and -l2 (-10Ko).I use a quantization of 0.935 and 0.88 (kind of quantization), and I decrease residual coding on the first order wavelet image. I have updated the demo page: http://nhwcodec.blogspot.com/ . These 2 lower quality settings are still experimental.If you could find time, would be interested in any

thanks very much for " ffmpeg2theora --two-pass -V 1234 inputfile.avi " what is --optimizer , awould be possible to add --grain like you get in MPEG2 video

We've implemented a vorbis decoder based on Tremor and as part of the documentation we're also writing about psycho acoustic models and encoding. We're quite up to date with the decoding process and psycho acoustics in general but unfortunately not on the psycho acoustic encoding used in Vorbis. We have a few questions that would we would be very thankful to have answer to: Which

Hi all, [For the uninitiated: a "peeler" is a program that transforms a Vorbis stream into a smaller, (somewhat) lower quality Vorbis stream, and does so quickly, by just throwing out some data.] After having prototyped several peelers that aim to peel to a certain filesize, or to a certain quality, with mixed success, I've now taken a different route: a peeler that aims for the

Hi all, [For the uninitiated: a "peeler" is a program that transforms a Vorbis stream into a smaller, (somewhat) lower quality Vorbis stream, and does so quickly, by just throwing out some data.] After having prototyped several peelers that aim to peel to a certain filesize, or to a certain quality, with mixed success, I've now taken a different route: a peeler that aims for the