Need to encode ogg to very low bitrate, but how?

[RathO]

Actually i cant go lower than 56kbits using BeSweet via the GUI or The OGGMachine...

I wanna encode Director's Comments @ like 32kbps...

I can see that quality cant go lower than 0.001 for ~58kbps...

Anyone can suggest? Any solution?

[Pasqui]

use quality = -0.1 (you can type the value as it is not in the list)

[dTb]

Generally you need to downsample the audio to achieve very low bitrates with ogg vorbis.
Bitrates for vorbis often end up lower than those stated by oggmachine, try encoding the commentary at 0.001 and you will probably find the average bitrate is lower than 58kbps.

[Eric B]

Originally posted by RathO I wanna encode Director's Comments @ like 32kbps...
Me too. So I've first converted AC3 to wav, and then :
oggenc --downmix -b32 "audiotrack.wav"

I think downmixing to mono is a good idea to keep 'correct' quality.
I've also tried a resampling @ 32Khz, but thats wasn't a very good idea because it's played accelerated in OGM since I've an other track @ 48Khz.

An alternative is to use "speex", but the output .spx file can't be mux in a OggMedia contenair, so it's not a good solution for me.

[RathO]

@Pasqui:

use quality = -0.1 --> Good! gives me a ~38kbps and didnt have to downmix from 48kHz. I think ~38 is fair for Director's Comments. :D

@dTb:

I didn't get lower than 58kbps with the 0.001 setting. :(

@Eric B:

What is speex? cause i have some movies with such downmix audio (for Director's Comments) and i cant mux them with my other 48kHz audio in OGM cause of speed problem... and id like to at least mux them in the avi...;)

Thank You!

[RathO]

And is it possible to go from a 24kHz file back to 44kHz without speed problem? i find so annoying the fact that i cant mux it... (and yes i deleted the ac3 source!...)

AYAA!!

[Eric B]

I've encoded some audio tracks in mono, but now, I've got a problem at playback which is 2 times faster, so I can't recommand yet to downmix to mono WHEN you keep at least one stereo audio track.

My problem is a movie in OGM container, with 2 Ogg Vorbis audio track, one is stereo, and the other is mono.

[RathO]

Reply that follows was sent to RathO by CTB:

What I do for commentaries is as follows:

Use BeSweet to decode ac3 with SSRC to desired sampling rate. IMO 32kHz seems to work best with commentaries. If possible, use a program to create a mono wave (meaning, an averaging of the L and R channels) since this seems to aid compression in Vorbis. The trick is simply to encode Vorbis to stereo, while up-sampling to 48kHz (even include a 16,000Hz cutoff switch if you are suspicious). There are command line switches, but in my experience, it is easily accomplished with the newest version of OggDropXPd (I am using 1.6.9 currently). It applies bits to the 32kHz signal (meaning, you have a reduction in file size), but acknowledges 48Khz: making ogm playback possible. Very effective.

Using this method I fit all 4 commentaries from the LOTR DVD into my OGM ;-)

-CTB