search for: perceptual

I quote from "Principles of Digital Audio" by Ken C. Pohlmann: "Because perceptual coders tailor the coded signal to the ear's acuity, they similarly tailor the required response of the playback system itself. Live music does not pass through amplifiers and loudspeakers, it goes directly to the ear. But recorded music must pass through the playback signal chain. Much of t...

...ogg-file, any identic parts of compressed and uncompressed audio should be eliminated. Of course there's always a "rest" of sound because the encoder is not lossless. Could this "rest" be an indicator for the quality of the encoder ? I know that evaluating the quality of a perceptual encoder with any technical equipment is nearly impossible and it would be better to let the ear do this. But I'd like to know what you think about this idea . Greetings Stoffke <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg...

Hi Has anybody done THD or THD-N measurements with the CELT Codec (bext would be on various bit rates) If someone could share results for Mono at 64kBit and Stereo at 128 and 196kBit it would be great. thank you very much Jochen -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/opus/attachments/20100817/b1da17cc/attachment-0002.htm

Hi, Does anyone have an idea about the possibility to apply psychoacoustic models as the ones in mp3 or AAC to a CELP coder? Thanks! /Pontus <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'speex-dev-request@xiph.org' containing only the word 'unsubscribe' in the

...way. <p>Tom <p>Christian Buchner wrote: > > > Does anyone have an idea about the possibility to apply psychoacoustic > > models as the ones in mp3 or AAC to a CELP coder? Thanks! > > > /Pontus > > This is (sort of) done in the decoder with the optional perceptual > filtering. Speex tries to shape the noise so that it sounds more > pleasant, I believe. > > To really use perceptual coding, one would require fine granular > control over quantization noise in various spectral bands. Speex > is not a subband coder and has no such control. But...

Hi, I have a newbie question, and a not-so-newbie one. I've just found out about Ogg, and I haven't been able to find a clear answer in the many webpages this proyect has (btw, why not create just one site instead of vorbis.com, ogg-vorbis.com...). The question is, does Ogg use perceptual coding, like mp3 does? And if so, would it be possible to build an encoder in such a way as to take one input stream and make it produce 2 different files? One file encoded at 64kb, and the other file with the information dropped from the stream that would have made the resulting encoded stream...

...h > > --enable-fixed-point --enable-arm-asm. All narrowband modes work in > > real-time with complexity 1 (some work with higher complexity) and some > > wideband modes also work (up to ~20 kbps) at complexity 1. One thing > > that doesn't work in real-time yet though is perceptual enhancement, so > > you must turn it off for now. > > Is this an option I must specify in order for it to be off, or is it off > by default. speexenc --help doesn't make it obvious. These are options that must be passed to the configure script. Basically, what it does is defi...

...following two frequencies. 1596Hz at -31.3dB 3200Hz at -48dB These two frequencies are present in both Narrow Band and Wide Band modes. I've tried a number of different configurations and these two frequencies are always present (quality set to 10 or default, the complexity set to default, perceptual enhancement turned on or off). I have not determined how to correct this problem but wanted to provide additional information. Cheers! Jason

Dear R-list members, I need an help with the Multidimensional Scaling analysis (MDS). So far I used the cmdscale() command in R, but I did not get the perceptual map I would love to see, and I would like to know if it is possible to get it using R, and if yes how. I also had a look to the functions isoMDS() and sammoc() but with no luck. I summarize the experiment I performed, and I would ask you an help to show me how to analyze in R my results. I simula...

...lot of bits in the LF because of that". > It could also be just the MP3 encoder being silly, or other things. Was the original poster speaking about the SILK or the CELT derived mode? Because at least wrt SILK (and the rest of the LPC derived codecs) there is an additional explanation: perceptually matched synthesis. If you look at things like the GSM/UMTS series codecs, they can seem *really* bad in a naive noise floor comparison, while sounding better at low bitrates and when applied to speech-like signals. That's pretty much the reason LPC derivatives are used in the first place,...

...1 and noticed that the waveform the I got after encoding and decoding on the new versions (beta1,beta2) is much more different than the original than on version 1.0.5. I also ran a PESQ comparison test on 700 voice samples and got better results in the older version (I used quality 9, and disabled perceptual enhancement). Do you know what can cause these changes? My application requires the waveform after decoding to be as similar in shape to the original, so if the difference is the result of some new addition to the encoder i would like to know how to turn it off. Thanks, Aviv

[ I'm not in the list because I didn't find a digested version; please move the lists to sourceforge.net, and we would have the digested version. I read the replies from the archive. ] Hello. Would it be possible to allow Vorbis use the same codebook for multiple files? I could keep a 650 MB codebook on CD-R and use that for all my audiofiles. If that is possible, how much the

I was wondering if the developers were using anything to "objectively" test the quality of the speex vocoder. For instance PSQM or one of the many derivatives. Mean Opinion Scoring seems an expensive route. Is there some open source software to use for this? <p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To

...slightly out of tune, or out of phase. Good head phone definitely help, but even high end sony's like the MDR-7506's and the MDJ-700s are only just able to produce the subsonics effectively to hear it. [Ogg is not free from patents.] The entire concept of a phsychoacustical model or a perceptual model for endcoding the material (not just the encoding step itself) is covered under at least 50 different patents by companies world wide, and rightfully so ... Not only can you patent the process of encoding the file, but the principles of how you get there. Why? Because they are novel ideas...

...resent thousands or tens of thousands of points, but all I read from them are density and distribution --- the gene names cannot be shown. At what point, would a sunflowerplot-like display or a smooth gradient be better? When two data points drawn as 50% gray disks are small and tangent, are they perceptually equivalent to a single, 100% black disk? Or a 50% gray disk with twice the area? What problems are known about plotting with disks --- do viewers use the area or the diameter (or neither) to gauge weight? As you can tell, I'm a non-expert, mixing issues of data interpretation, visual perc...

...on ARM. In order to do that, compile with --enable-fixed-point --enable-arm-asm. All narrowband modes work in real-time with complexity 1 (some work with higher complexity) and some wideband modes also work (up to ~20 kbps) at complexity 1. One thing that doesn't work in real-time yet though is perceptual enhancement, so you must turn it off for now. As usual, please test it and see if it breaks. I'm especially interested in feedback about how it behaves when decoding files that were encoded with a floating point version or vice versa. Jean-Marc -- Jean-Marc Valin, M.Sc.A., ing. jr....

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...n't have that. I can use the stock frame sizes ( 120, 240, 480, 960, 1920, and 2880 sample/frame). My conclusion is that I could set up Opus for 48K (stereo), and in reality run it at 44.1K, as long as I use stock frame sizes, and it would be fine. The only issue I can think of is any of the perceptual stuff will be off by -8%, e.g. crossover/mask frequencies, etc. Or is that true? And with Opus_custom is all that stuff recalculated? If I do need to go to opus_custom, it seems that it's still best to use the stock frame sizes, true? Thanks! Marc

...either 'wide' or 'narrow'. vbr: variable bit rate - either 'on' 'off' or 'vad'. cng: comfort noise generation - either 'on' or 'off'. mode: speex encoding mode. Can be {1,2,3,4,5,any} defaults to 3. penh: use of perceptual enhancement. 1 indicates to the decoder that perceptual enhancement is recommended, 0 indicates that it is not. Defaults to no. Encoding considerations: This type is only defined for transfer via RTP as specified in a Work in Progress. Security Considerations:...

> Does anyone have an idea about the possibility to apply psychoacoustic > models as the ones in mp3 or AAC to a CELP coder? Thanks! > /Pontus This is (sort of) done in the decoder with the optional perceptual filtering. Speex tries to shape the noise so that it sounds more pleasant, I believe. To really use perceptual coding, one would require fine granular control over quantization noise in various spectral bands. Speex is not a subband coder and has no such control. But it already does a better job t...