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Topic: Speex quality presets? (Read 5000 times) previous topic - next topic
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Speex quality presets?

How about tested presets that yield good qualiy on a certain range of material? (e.g. pure audiobook, radio play, etc.)

Testing could be done on very popular speech contents, e.g. LOTR or War Of The Worlds, famous speeches...

Any commandline recommendations?

It'd certainly increase speex popularity!

Speex quality presets?

Reply #1 –
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How about tested presets that yield good qualiy on a certain range of material? (e.g. pure audiobook, radio play, etc.)

Testing could be done on very popular speech contents, e.g. LOTR or War Of The Worlds, famous speeches...

Any commandline recommendations?

I thought it was already simple enough, no? You just set the --quality option with whatever you want as quality (I can't decide for you) and then if you want VBR (that's application-dependent, you add --vbr). I don't see how presets can make that simpler. Or did I miss anything?

Speex quality presets?

Reply #2 –
Ok, but what about this complexity setting? Does it increase quality when set to a higher level? I encoded material with a complexity of 2 and 10 (both with max. quality=10), but the resulting files where nearly identical in filesize, so what is complexity all about?

Speex quality presets?

Reply #3 –
Quote
Ok, but what about this complexity setting? Does it increase quality when set to a higher level? I encoded material with a complexity of 2 and 10 (both with max. quality=10), but the resulting files where nearly identical in filesize, so what is complexity all about?

Just as a guess, before jmvalin comes back and gives us the authoritative answer, I think it might be similar to the q value in LAME.  Which, if you don't already know, changes the algorithm used for VBR files (lower value for q = higher quality but slower encoding.  Just so you don't ask later 2 is used for the --alt-presets; 1 and 0 are considered experimental), without affecting the bitrate a great deal, or at all.
gentoo ~amd64 + layman | ncmpcpp/mpd | wavpack + vorbis + lame

Speex quality presets?

Reply #4 –
If that's true, the quality switch is not the only option to affect quality (as said above). Consider the narrow- / wide- / ultrawideband issue, automatic mono-downmix... presets for speex would help average Joe create better-sounding speex files!

Just my 0.02 €

Speex quality presets?

Reply #5 –
Quote
If that's true, the quality switch is not the only option to affect quality (as said above). Consider the narrow- / wide- / ultrawideband issue, automatic mono-downmix... presets for speex would help average Joe create better-sounding speex files!

First, considering the complexity setting, the default (3) should be good for most uses. Most of the times it won't make a big difference in the final quality, so it's mostly a matter of how much CPU you have. Obviously, this is something that's of no use in presets. Regarding the sampling rate, Speex will always encode at the sampling rate you give it (sorry, no re-sampling, this is not a kitchen-sink codec). So basically, all there's left is the --quality setting, so I don't see much need for presets.
 

Speex quality presets?

Reply #6 –
Downmix to mono, resample to 16000 Hz, use --quality 3 or 4 and --vbr
--comp doesn't matter, standard value is ok