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An idea would be like for WMA 9 lower bitrates (32-42-48Kbps) to use a 'crystallizer'; which is basically a harmonics booster focussed at transposing sharp tones some octaves higher.<BR>
Eg:<BR>
A file has been recorded @ 20khz computer (or 10khz real life) to preserve space.<BR>
While playing back the file sounds a bit mushy, almost as if someone was speaking through a cardboard wall. The higher frequencies are missing, and you can easily perceive that the file is a low bitrate file.<BR>
<BR>
By harmonically transposing frequencies from 6 to 10Khz with one octave, and overlaying the original file with that stream, one can create the perception that an additional stream of 12-20Khz has been encoded. This effect is extremely usefull since altered (or artificial) frequencies below 100Hz and above 6Khz are enormously hard to hear!<BR>
Especially in speech!<BR>
In music this would translate to that the cymbals of all songs or drums sound about the same, and one can clearly pick the original recording from the compressed one.<BR>
But for voice this is hardly noticable since very few articulated tones actually go over 10Khz. <BR>
The letter 'S' and 'C' are two of them.<BR>
<BR>
By this a much higher quality is perceivable (on low bitrates), the software only needs to be included in the decoder, and technically could still work with older compressed Speex files.<BR>
<BR>
I just wanted to throw in this idea, since it works quite nice on WMA; and for now I'm encoding speech files with 48kbps (speech with background music) or 32kbps (speech as being preaching, bookreading or lectures).<BR>
I wish to see that number going down though. If Speex performs better, has smaller files, and can compete with 32kbps WMA9 encoded files, I might become interested in testing out the product, and perhaps switching over!<BR><br /><hr />Voeg vrienden toe van LinkedIn & Facebook aan je Windows Live netwerk. <a href='http://www.microsoft.com/belux/nl/windows/windowslive/products/social-network-connector.aspx' target='_new'>Zo heb je iedereen bij de hand. </a></body>
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