search for: psnr

...material will be helpful to some of you. <p>Regards, <p> ---- Gabriel Bouvigne www.mp3-tech.org personal page: http://gabriel.mp3-tech.org <strong>attached mail follows:</strong><hr noshade> Hello I just looked at your vp3/mp4 comparison. In this test you used psnr to compute differences between original and coded samples. You mentionned some drawbacks of psnr. I totally agree with the fact that a few differences (lets say a small lumi difference) might give a very bad psnr. That is why a few years ago, I made a small tool to bypass those problems. The to...

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

...e" 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 consistent PSNR. Apples to bears. "VP3 preferred rgb" very suspicious, as YUV 12 (ie planar YUV with U and V each subsampled at 1/2 resolution in both directions) is the native colorspace. These sorts of conversions are a huge source of innacuracies on PSNR tests. To be frank, it's great that yo...

Hi Gabriel, I m trying to author a test suite for video codecs. Can you guide me how to go about it? I need some ideas to get started with. Thanks Jina -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/theora/attachments/20050906/3c71295d/attachment.htm

Hi Gabriel, I m trying to author a test suite for video codecs. Can you guide me how to go about it? I need some ideas to get started with. Thanks Ramu Can u reply for this mail. --------------------------------- Yahoo! India Matrimony: Find your partner now. -------------- next part -------------- An HTML attachment was scrubbed... URL:

...vely (ie knowing that a simple scene is coming up, they can increase quality on the cut so you don't see an ugly transitional period of a few frames). True CBR is basically this strategy rigorously enforced against a given transport speed and playback buffer model. This sort of relates to the PSNR discussion in the following way: internally, when making various encoding choices (block type, quantizers), most video codecs simply use some variation of MSE (mean squared error, which is what PSNR is derived from), or more typically SAD (Sum of Absolute Differences), which is a very similar metri...

Hi List, Just batting a few ideas around here, but would it be possible to include in to the codec, estimation for common video artifacts that occur in the analogue world? For example, anything that's gone through a composite stage will likely have dot-crawl and false colour - if we can recognise this effect in the encoder, we can treat it as a special case. Other artifacts that come to

...decoding [theora @ 0x3ef4a0]vp3: first frame not a keyframe Error while decoding stream #0.0 5. quality is visually very poor.. both in my player, and others like mplayer. Likely due to (3) and (4). If I use ffmpeg to encode the video, quality is fine. By decoding with ffmpeg to a file, I run a psnr tool on it and it says PSNR is 26.318160. This is using J's latest http://v2v.cc/~j/ffmpeg2theora/download.html (thanks!) Here's an overall script you can criticize :: *************************:: ogg container test matrix:: ************************* oggenc2 -o sync2.ogg sync2.wav :: ****...

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

One thing I have noticed when encoding VCDs is that often videos with complex backgrounds don't compress nearly as well as those with simple ones. Part of the problem is that TV cameras seam to have the focus so that the entire image is clear rather than focusing on the foreground (and blurring the backgrounds). The result is that a good number of bits are wasted trying to perfectly

Hi, I guess this is a good time to start putting together a wish list for a video codec. I see that for audio the compression is around 10X for reasonable quality. I am sure this will start its own thread of conversation. For video you can do 40X fairly easily and the big task is to go to 80X or 100X with reasonable picture quality, say, a peak luma SNR of more than 30 dB. Uncompressed

...resting range coder (division-free) that can be skipped to code raw bits or with huffman, rice-golomb... Wavelet transforms, SPIHT, context modeling have improved since 2008, so why no new updated wavelet codec, as it was the case of HEVC for H.264 (Rududu is similar in performance with x264 intra, PSNR- and SSIM- wise)? -Do wavelets have so much bad reputation?- Ok that's right the NHW codec is a wavelet codec, but it's a totally new approach, with an emphasis on speed (extremely fast with a good visual quality, neatness/sharpness preserving) mainly designed to fit with portable devices....

Hello, I am still working on very high compression for the NHW Project, but I find the current version good, it has a good neatness of image, which I find visually more pleasant than other codecs that are optimizing for PSNR, SSIM,... Furthermore the NHW Project is still very fast and royalty-free. I dedicated this past year to the NHW Project and I could make very good improvements (like quality improvements, adding of high and very high compression, Linux version, NHW neatness metrics, image study and comparison wit...

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

Hello, Definitely not any (constructive) comments on the NHW Image codec? According to my tests, it can compare good with reference codecs like x264 intra and WebP. Yes, the codec is still experimental and is optimized for visual (subjective) evaluation, not PSNR.Its main feature is again that it would have a little more neatness/sharpness and a little less precision (residual coding is applied on "sub" wavelet images or orders and I take advantage then of the neatness the wavelet 5/3 filterbank can have).The entropy coding schemes for each parts:...

...that if I say that the NHW codec would have more neatness/sharpness, this must be also accompanied with objective measure.But the neatness/sharpness measure is quite complex to define, and implement. But at classical visual review step, I would find that the NHW codec would be less blurred (maybe PSNR would like blur?...) with more neatness/sharpness, with the normal settings (-l2->-h3 settings).Do someone agree with this? And also, is visual review a good or sufficient method for "pointing" the advantage of a codec? Would be really interested in the opinion of the experts on these...

...r strong denoising, details washing-out inside the contours.The resulting image can appear then a little "cartoonish" but visually it's the result I neatly prefer compared to x264, WebP, Rududu results and artifacts at these same very high compression ratios.(This is also confirmed by PSNR and SSIM...) So for -l8 very high compression setting and above, I will need to find a new approach of compression and perceptual quality, and new processings.Again if you have skills in image and signal processing, compression, machine learning, and other, and you think you can help us, do not he...

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

Hello! I'm trying to use ffmpeg2theora to encode raw (.yuv) files in I420 format (just frames, no headers at all), but failed to find corresponding input format. Is there any documentation of supported formats for ffmpeg2theora? Or maybe there is another command-line tool for Windows to encode raw video using Theora algorithm? Thank you for help! Alexander.

"... we need a baseline to work from - one standard format that (if all else fails) everything can fall back to. This doesn?t need to be the most complex format, or the most advertised format, or even the format with the most companies involved in its creation. All it needs to do is to be available, everywhere. The codec in the frame for this is Ogg Theora..." :)