Hello, <br><br>I just signed up to this mailing-list (note: my first mailing list at all), because I'm having some problems related to speex.<br>Let me just introduce you to what I'm doing.<br><br>I am writing a short (really short) paper about VoIP techniques, especially audio codecs for speech. <br>
I pointed out basic technologies behind audio codecs; vector quantization, lpc, long-term prediction and some more.<br><br>I planned to compare G711(.1 eventually) and speex with reference to filesize<br>(which is a bit weird, since the encoded g711-files are 6 times larger than the original wave files - but this is another matter), MoS value, <br>
and a subjective opinion, wether I can still understand the file, or not.<br>The MoS value is (or rather <i>should be</i>) calculated by PESQ (ITU P.862<span style lang="EN-US">: <a href="http://www.itu.int/rec/T-REC-P.862/en">http://www.itu.int/rec/T-REC-P.862/en</a>).<br>
(I know the pesq scale ranges from -0,5 - 4,5, where MoS is usually from 0 - 5)<br><br><b>Pesq Settings:</b><br>R2a: Sampling Rate: 8kHz, Overall bit rate: 80kbit/s<br>R3: Sampling Rate: 16kHz, Overall bit rate: 96kbit/s<br>
<br><b>Pesq Results:</b> <br>R2a (mode 2) of G711 returned Mos-Values from <u>0.656</u> to <u>3.33</u> (parameter +8000 in pesq)<br>R3 (mode 4) of G711 returned Mos-Values from <u>3.981</u> to <u>4.269</u> (parameter +16000 in pesq)<br>
<br><b>Speex Settings:</b><br>To get comparable results I decided to use settings that conform with the G711 ones. Command-Line Parameters:<br>"mode 2": "-n --comp 10 --quality 10 --bitrate 80000"<br>"mode 4": "-w --comp 10 --quality 10 --bitrate 96000"<br>
</span><br><span style lang="EN-US"><b>Speex Results (this is where it starts to be weird):</b><br>mode 2: Mos Values from <u>2.541</u> to <u>3.211</u> (parameter +8000 in pesq)<br>mode 4: Mos Values from <u>2.045</u> to <u>3.355</u> (parameter +16000 in pesq)<br>
<br>I tried to get better values, at least in mode4, for like 2 hours, but I did not get something that corresponds to this: <br><a href="http://speex.org/comparison/nb_codecs_small.png">http://speex.org/comparison/nb_codecs_small.png</a> (Speex.org Website).<br>
The fact, that a bitrate of like 25kbit/s results in a score of nearly 4,5 is confusing me like hell. (compared to my results)<br><br>First thing I tried was just "speexenc origfile.wav destfile.spx", but the result did not satisfy me.<br>
<br>The used wavefiles are created in Cubase5.1, 16bit and 16kHz. <br>Im using </span>1.2rc1, compiled with cygwin, running on Windows 8.<br>The 1.2beta3 kept crashing on Win8 and Win7 using the same audiofiles.<br>I also tried using 1.0.5, but the (MoS)results were not satisfying.<br>
<br>I have no clue why the score is at such a low level (compared to the graphic below).<br><br>Let me already thank you for your help.<br><br>Greetings<br>Olli<br><br><br><span style lang="EN-US"></span>
<a href="http://www.dict.cc/englisch-deutsch/altogether.html"></a>