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Topic: Transcoding from Vorbis Q6 to Q2 (Read 4004 times) previous topic - next topic
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Transcoding from Vorbis Q6 to Q2

What's the general consensus on transcoding Ogg Vorbis files down to a lower bitrate.  I'm presuming that because the psychoacoustic model is the same that quality loss will be less then transcoding between formats?

I know that trancoding is bad, but I want to be able to fit the files on my pda and Q6 produces files that are a bit big!  And before you ask, no I don't have the original CD's to hand.
Dan

Transcoding from Vorbis Q6 to Q2

Reply #1 –
Personally I think halving the bitrate is enough of a drop for it not to matter seriously that you are transcoding rather than making an original.  Rather than a quality difference, you might only notice the transcoded files are 1-2kb/s higher to compensate for the lossy source.
< w o g o n e . c o m / l o l >

Transcoding from Vorbis Q6 to Q2

Reply #2 –
Quote
What's the general consensus on transcoding Ogg Vorbis files down to a lower bitrate.  I'm presuming that because the psychoacoustic model is the same that quality loss will be less then transcoding between formats?

Not necessarily. If the psymodel is the same for two subsequent encodings, the errors will tend to add up at the same places, which is not necessarily a good thing.

Depending on the samples I guess it might even be considered "worst case".

Quote
I know that trancoding is bad, but I want to be able to fit the files on my pda and Q6 produces files that are a bit big!  And before you ask, no I don't have the original CD's to hand.


You don't really have to justify yourself, it's your music and your decisions..

It should be written in the "HA terms of use":

People shall flame only if the person clearly would delete the originals after transcoding 

By the way.. which PDA is it ?

Regards

Edit:  Mac is right, if you're shaving, say, ~30% (wild guess) of the filesize, there's little need to worry.

Transcoding from Vorbis Q6 to Q2

Reply #3 –
thanks for the replies.

it's an iPAQ 2210, using PocketPlayer to play.

And I know I didn't have to justify it, I just wanted to avoid the replies that say 'Don't ever transcode ever, never EVER EVER!'

And it's more like 50%, Q6 to Q2 is nominal bitrate 192kb/sec to 96kb/sec.

Thinking about it, could I just bitrate peel the files?  Would this give me better results than transcoding?  If so, where might I find a tool to do this?
Dan

Transcoding from Vorbis Q6 to Q2

Reply #4 –
I tried doing this, and I have to say it sounds much, much worse than I expected.

Just do one or two songs you know well and you'll pretty quickly realise what I'm talking about (or not - in which case you're not sensitive to whatever was annoying me).

I get really nice results when I transcode from an MPC to ogg -q2.

My solution was to buy a bigger SD card for my palm.

Transcoding from Vorbis Q6 to Q2

Reply #5 –
Quote
'Don't ever transcode ever, never EVER EVER!'

Nah. Some threads or posts may have given you a mistaken impression (they did mislead me before), but the flame war against transcoding is about people who transcode, and claim that the transcodes sound better, and encourage others to their point of view.

Transcoding is accepted (maybe even recommended, if only to save your CDs from being scratched and damaged by multiple rips and general handling) when you want to listen to your files on a portable, as portable space is nowhere near typical hard disk space yet (Maybe for some, the iPods and Rios have broken the barrier).

Just do not share the transcodes with others (by others, I usually mean the people using lossless or Musepack or Vorbis or LAME mp3 at high bitrates here )

Transcoding from Vorbis Q6 to Q2

Reply #6 –
Quote
Personally I think halving the bitrate is enough of a drop for it not to matter seriously that you are transcoding rather than making an original. Rather than a quality difference, you might only notice the transcoded files are 1-2kb/s higher to compensate for the lossy source.

Have you actually done this, Mac?  I mean, your sentence/paragraph makes sense, but in reality it sounds way beyond poor.

Focus: I have a big problem with people transcoding to portables.  I just dont get it.  When I listen to music on portable its like "Headphones, Music", and thats it, and I pick up many subtle nuances that otherwise, with "Hi-Fi, Speakers, Computer Noise, Fan, me moving around the room loads" wouldn't.  I almost want higher quality music for my iRiver (Yes, I am immune to hiss, and cant ABX wavpack at all), and lower quality stuff for home listening.  I just dont get it.  Do people stick with the 50p earbuds that come with the unit, in which case any real discussion of audio compression is seriously moot? 

[span style='font-size:8pt;line-height:100%']Edit: And anything but the worst headphones show up the of a transcoded lowbitrate file[/span]

Transcoding from Vorbis Q6 to Q2

Reply #7 –
Well, not many people can afford the 10-30 GB iPods and Rios, and even the i-Rivers. When you're left with only 128 MB of flash memory or less, you'll want to maximise the space in there. I use Musepack at -q5 on my HD music files, yet I still find wma files encoded at 128 kbps very nice to hear. Maybe I'm not used to headphones; maybe I have lousy ears after all (and at 18 yrs old too  ), and I don't listen to stuff at earsplitting levels.

Transcoding from Vorbis Q6 to Q2

Reply #8 –
So what about bitrate peeling then?  Do any utilities exist to do this yet?  A search of the forum hasn't turned anything up.
Dan

Transcoding from Vorbis Q6 to Q2

Reply #9 –
The noise amplification in Vorbis files keeps me away from transcoding Vorbis to Vorbis cause I think listening to such a file really won't be a pleasure.
I love the moderators.

Transcoding from Vorbis Q6 to Q2

Reply #10 –
Re: Peeling
Quote
I tried doing this, and I have to say it sounds much, much worse than I expected.

If you think about it, such a drastic peel will never sound as good.

q2 uses a different (lossy) stereo model than q6 (lossless) does. A peeler (by definition) isn't going to be able to change the stereo model. I strongly suspect that re-encoding will always sound better for such a large change in bitrate.

Peeling is still useful, of course (streaming, other applications with CPU time constraints), but in this case we have lots of time available for a full-blown re-encode.

Transcoding from Vorbis Q6 to Q2

Reply #11 –
Quote
If you think about it, such a drastic peel will never sound as good.


I think you have this the wrong way around: I was re-encoding -q6 to -q2.

I haven't tried the current peeler, but a properly implemented peeler would hopefully do a better job than the rubbish sounding re-encodes I get.

It would be nice to think that someone could write a tool that converts lossless to lossy stereo - the bitrate saving would be non-negligible.

I would think that an ideal tool for portables would do a conservative amount of peeling, convert the stereo to lossy, and do a re-huff.