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Can get speex to work better than ogg for books. Why?
junglemike
post May 31 2006, 15:46
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Hi', since speex decoder is available now for Palm OS also, I was wondering if I can get some good results for audio books . Currently I'm using 22khz around 20kbps (q -2 ) with ogg.
Whatever settings i tried (quality/ bitrate/complexity) - I can't bet speex to sound better ogg per same bitrate. This doesn't make any sence, because speex is supposed to be tuned specially for speach.
Moreover, it doesn't obey my commands, for example I wanted to force it to use bitrate of 10 kbps
QUOTE
--bitrate 10 --vbr --comp 6 o:\test\16khz.wav o:\out.spx

Instead, i get bitrate of arund 20, which sound much worse than ogg@20kbps. Why?
Can anybody help me?
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TheGrishnav
post Dec 5 2006, 00:37
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I've been doing voice encoding of radio traffic with ogg vorbis (-q -1) and speex for quite a while now. The speex files come out worse sounding and larger than the ogg's every single time.

Plus the speex encoder is hella unstable.

I blame the problems on the speex encoder's immaturity. Maybe I should see if there is a newer version out (I've just been using vorbis for the past several months... gave up on speex)

The sad part is that the agc and the denoising are _really_ helpful.

Nothing scientific, just a bit of anecdotal evidence that may be helpful. sad.gif

arecord -f S16_LE -r 16000 | oggenc -q -1 - -o "`date +"%F %Hhr %Mmn %Ssc %Z"`.ogg"
arecord -f S16_LE -r 16000 | speexenc -w --quality 6 --vbr --denoise --agc -V - "`date +"%F %Hhr %Mmn %Ssc %Z"`.spx"

This post has been edited by TheGrishnav: Dec 5 2006, 00:38
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JEdwardP
post Dec 5 2006, 20:10
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I've also given up on Speex, at least temporarily, in favor of Vorbis. I'd been using Speex to encode my audiobook CD's and cassettes ever since Windows binaries of it first appeared, and found its superiority to LAME easily ABX-able (LAME almost always produced an annoying metalic noise at lower bitrates, which Speex did not).

The latest Speex beta, I've found, often produces a similarly annoying noise, which Vorbis does not, and was again easily ABX-able. Ultimately, I found that while Speex is SUPPOSED to be optimized for bitrates up to 44kbps and sampling rates of 8, 16, and 32khz, it only seems to work consistently well at 8khz.

Even for those cases in which I cannot ABX a difference between Speex and Vorbis, I've found that Vorbis rarely produces significantly larger files, so I saw no reason to continue with Speex.

I've wondered if it's the case that most modern audiobook recordings can't be considered "pure speech", even when no background music or sound effects are used.
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