Speech Codec

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JamesWoodcock
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Speech Codec

Post by JamesWoodcock »

http://www.speex.org/

Have you ever considered using this for compressing speech as this is its primary use rather than ogg and mp3 which is aimed at music.

clem
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Post by clem »

I'm not sure what the benefits would be

features look like it's mainly aimed for telephony over the internet, plus having one more library to be compiled in increases file size and makes the whole project more complicated

clem

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eriktorbjorn
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Re: Speech Codec

Post by eriktorbjorn »

glidem wrote:http://www.speex.org/

Have you ever considered using this for compressing speech as this is its primary use rather than ogg and mp3 which is aimed at music.
The idea has been brought up a few times, but I don't know if anyone has bothered to check if Speex would really provide any tangible benefits. A few years ago, I tried encoding a WAV file with Speex. The resulting file was about the same size as an Ogg Vorbis-encoded file, but the sound quality was considerably worse.

It appears to have improved a lot since then, though.

I'm not sure how many of the games keep the speech separate from the rest of the sound effects, though. The Broken Sword games do. Any others?

JoeysAudioChip
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Post by JoeysAudioChip »

Any compression codecs aimed specifically at voice would be aimed at the frequency range of approxiamtely 300-3500Hz whereas codecs like OGG and MP3 obviously cover the full 20Hz-20kHz range. As Clem says, Speex is aimed at VoIP. I suppose with most things it's a case of quality over file size. I'd personally stick with OGG/MP3 though.

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JamesWoodcock
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Post by JamesWoodcock »

Just a thought thats all :), the WMP codec for speech is VERY good and very small, but SFX might cause problems!

JoeysAudioChip
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Post by JoeysAudioChip »

I'll have to check that WMP codec out. I've always found the WMA codec's to be quite good in general. I use Skype occasionally and the codec it uses is very impressive.

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LogicDeLuxe
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Post by LogicDeLuxe »

JoeysAudioChip wrote:codecs like OGG and MP3 obviously cover the full 20Hz-20kHz range.
They can do that, but they don't have to. With good encoders, you can preselect a band you want to be encoded, which apparently can save a lot on the bitrate. Getting rid of some less important frequencies is the whole point of lossy codecs anyway.

pi
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Post by pi »

Keep in mind that neither WMP nor WMA are free codecs, and there are many platforms which don't support these formats. As ScummVM is supposed to be portable (and stay that way), it's not favorable. Of course it would be possible to add in optional support in the Windows port, but that'd require someone to do it :)
As for Speex support, I don't think it would lead to anything other than hurting the sample quality. We don't want Guybrush to sound as if he actually called from the carribean ;)

pi~

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