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Topic: Ogg CBR encoding? (Read 9650 times) previous topic - next topic
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Ogg CBR encoding?

I thought it is easily possible to encode Ogg files at a constant bitrate, but I tried OggdropXPD with a 96 kbps CBR setting, but it seems to me like ABR. When encoding the average bitrate goes up and down  . Why is that?
I tried using oggenc2.exe with the command line, the result was closer to the target bitrate, but still not CBR.
Is it possible to encode totally CBR, with all the frames at the bitrate I want?
I ask because of this new firmware for iRiver CD-players, which only supports bitrates from 96-160 kbps!
Thanks!

Ogg CBR encoding?

Reply #1 –
I can´t believe your iRiver really needs 100% "perfect" CBR (if so iRiver better should not claim Vorbis "support"). Have you tried something like "oggenc --managed -b 128 -m 100 -M 150"?

Ogg CBR encoding?

Reply #2 –
Have you tried the Post v1.0.1 compiles? They're the ones in which the CBR is supposedly sorted.

Ogg CBR encoding?

Reply #3 –
I have an Iriver too, but the iMP-550.
-q4 works great, no no need to use CBR.
Try it out

Big_Berny

Ogg CBR encoding?

Reply #4 –
Quote
Have you tried the Post v1.0.1 compiles? They're the ones in which the CBR is supposedly sorted.

Yes, that's the one I tried. But still I don't think it's 100% CBR.

Ogg CBR encoding?

Reply #5 –
Quote
I can´t believe your iRiver really needs 100% "perfect" CBR (if so iRiver better should not claim Vorbis "support"). Have you tried something like "oggenc --managed -b 128 -m 100 -M 150"?

But I would like to try out the lowest possible supported bitrate -- that would be 96 kbps CBR. I want to know how good it sounds...

Ogg CBR encoding?

Reply #6 –
I just encoded with this command line using Oggenc2.3 using POST LibVorbis v1.0.1 CVS:

oggenc2 -b 96 -m 96 -M 96 file.wav

and after encoding it showed average bitrate 97,5 kbps, so it's pretty close, but I suppose it's not CBR.

Ogg CBR encoding?

Reply #7 –
One more question. Is it OK to leave it at 44 kHz or should I downsample it to 32 kHz when encoding at 96 kbps?

Ogg CBR encoding?

Reply #8 –
Quote
I have an Iriver too, but the iMP-550.
-q4 works great, no no need to use CBR.
Try it out

Big_Berny

But what if there's a silent part in a song and the bitrate goes to 1 kbps? The song won't be played...

Ogg CBR encoding?

Reply #9 –
Quote
One more question. Is it OK to leave it at 44 kHz or should I downsample it to 32 kHz when encoding at 96 kbps?

I would leave it at 44.1 kHz.

Ogg CBR encoding?

Reply #10 –
Quote
But what if there's a silent part in a song and the bitrate goes to 1 kbps? The song won't be played...

If I understood correctly Vorbis uses larger window-sizes at low bitrate modes - which increases memory consumption (that´s the reason why some hardware players have minimum bitrates). AFAIK quality-modes are using constant maximum-windowsizes even if average bitrate drops below their target-bitrate. So even simpel parts of a song should be safe...

If I´m wrong - please correct me!

Ogg CBR encoding?

Reply #11 –
Quote
Quote
I have an Iriver too, but the iMP-550.
-q4 works great, no no need to use CBR.
Try it out

Big_Berny

But what if there's a silent part in a song and the bitrate goes to 1 kbps? The song won't be played...

I haven't a song with long silent parts, so I don't know.
But all the songs I tried worked.
You have to try it out!

Big_Berny

Ogg CBR encoding?

Reply #12 –
Quote
I just encoded with this command line using Oggenc2.3 using POST LibVorbis v1.0.1 CVS:

oggenc2 -b 96 -m 96 -M 96 file.wav

and after encoding it showed average bitrate 97,5 kbps, so it's pretty close, but I suppose it's not CBR.

Vorbis is a VBR codec by design, by forcing it to adhere to a particular bitrate you actually cripple the codec a little.

I would recommend encoding with -q 2 for your portable.  That should give you near enough 90-96 kbps average, depending on the music you encode.
Dan

Ogg CBR encoding?

Reply #13 –
This isnt really helpful, but isnt this a moot point?

When iRiver come up with a firmware that is Vorbis compliant, you'll be kicking yourself for having sh1tty encodes, and will have to redo them...

Just pretend that they didn't release the poor (I haven't tested it yet on my 250) 'support' which they have.

Ogg CBR encoding?

Reply #14 –
Quote
Quote
Quote
I have an Iriver too, but the iMP-550.
-q4 works great, no no need to use CBR.
Try it out

Big_Berny

But what if there's a silent part in a song and the bitrate goes to 1 kbps? The song won't be played...

I haven't a song with long silent parts, so I don't know.
But all the songs I tried worked.
You have to try it out!

Big_Berny

I have tried my -q 4 files and yes, they seem to play fine!

But the -q 6 files are not supported. I could not play them. (I have an iRiver iMP-350).

Ogg CBR encoding?

Reply #15 –
Quote
Quote
I just encoded with this command line using Oggenc2.3 using POST LibVorbis v1.0.1 CVS:

oggenc2 -b 96 -m 96 -M 96 file.wav

and after encoding it showed average bitrate 97,5 kbps, so it's pretty close, but I suppose it's not CBR.

Vorbis is a VBR codec by design, by forcing it to adhere to a particular bitrate you actually cripple the codec a little.

I would recommend encoding with -q 2 for your portable.  That should give you near enough 90-96 kbps average, depending on the music you encode.

I didn't try -q 2 out yet. It should work. But I would probably go with -q 3 or 4 to be more certain of squeezing in the supported bitrate range...

I must try, but I don't have time now. 

Ogg CBR encoding?

Reply #16 –
No, -q 2 is not good for my portable. I tried encoding an album with 13 songs and my iRiver only played 8 of them. 

Ogg CBR encoding?

Reply #17 –
don't bother to use vorbis on that crappy firmware then..