IPB

Welcome Guest ( Log In | Register )

 
Reply to this topicStart new topic
Other Dumbass Question
krsna77
post Oct 26 2001, 17:37
Post #1





Group: Members
Posts: 74
Joined: 29-September 01
Member No.: 35



Ok, here goes.

Clipping, being a problem with MP3 decoding, would often require normalization beforehand to compensate. For me, determining the proper normalization amount was often a degree of guesswork.

Then, MP3Gain came out. Problem solved.

I was wondering, is there a quantified amount, or formula, that each codec tends to increase levels by, and... if so, what is that value for Ogg Vorbis (and MPC, while we're at it)?

Reason I ask - if I encode to ogg, I would like to know the proper safe-but-sane normalization level geared for ogg. If it's not easily quantifyable beforehand, then at least is there a good method to detect and measure clips in ogg samples, so I can calculate the proper normalization amount myself to eliminate clipping for those tracks?

While I'm on it, will OGG / MPC ever have ReplayGain functionality, or something similar?
Go to the top of the page
+Quote Post
Garf
post Oct 26 2001, 19:24
Post #2


Server Admin


Group: Admin
Posts: 4884
Joined: 24-September 01
Member No.: 13



QUOTE
Originally posted by krsna77
I was wondering, is there a quantified amount, or formula, that each codec tends to increase levels by, and... if so, what is that value for Ogg Vorbis (and MPC, while we're at it)?


None of the codecs increase the volume. I explained this elsewhere on this board (don't ask me where though smile.gif).

The problem is that sometimes the output of the decoder contains largers peaks (which is different from actual volume) than the original wave. This is a digital audio processing artifact.

Because of this, it's impossible to give a fixed value.

QUOTE
Reason I ask - if I encode to ogg, I would like to know the proper safe-but-sane normalization level geared for ogg. If it's not easily quantifyable beforehand, then at least is there a good method to detect and measure clips in ogg samples, so I can calculate the proper normalization amount myself to eliminate clipping for those tracks?


If there is no clipping in the original wav, there should be no audible clipping in the Ogg decoder output either. The Ogg decoder has built-in clipping prevention. Basically, you do not need to worry about renormalization to avoid clipping. I just renormalize everything to 98% before encoding so I am sure there is no clipping in the original wav.

(don't ask me how it works, I have no idea. Monty once told me about this. I'll ask for more details next time I catch him)

QUOTE
While I'm on it, will OGG / MPC ever have ReplayGain functionality, or something similar?


If someone adds it, why not?

--
GCP
Go to the top of the page
+Quote Post
krsna77
post Oct 26 2001, 20:38
Post #3





Group: Members
Posts: 74
Joined: 29-September 01
Member No.: 35



QUOTE
None of the codecs increase the volume. I explained this elsewhere on this board (don't ask me where though smile.gif).

The problem is that sometimes the output of the decoder contains largers peaks (which is different from actual volume) than the original wave. This is a digital audio processing artifact.


Oh, ok. smile.gif I think actually I have been told this before, but this entire issue really is hard to get driven into my thick skull for whatever reason.

QUOTE
If there is no clipping in the original wav, there should be no audible clipping in the Ogg decoder output either. The Ogg decoder has built-in clipping prevention. Basically, you do not need to worry about renormalization to avoid clipping.


I have a tendency to believe you, however, I can think of one specific example (Alice in Chains - Dirt), that does clip very terribly, with nasty distortion, in OGG and MP3, until I normalize at ~0.84 (for MP3 - tho I use this value for OGG, its threshold may in fact be higher). Then it sounds fine (of course, I think this album really is pushed to the very limits).

Know of any good apps that can count clipped samples, so I can visually compare with what my ears are telling me?...

It's just that, for once and for all, I would like to eliminate all digital distortion in a easy, effective way, without using an insanely low "radio gain".

Again, thanks, and the tuned encoder kicks much ass!
Go to the top of the page
+Quote Post
Garf
post Oct 26 2001, 20:55
Post #4


Server Admin


Group: Admin
Posts: 4884
Joined: 24-September 01
Member No.: 13



QUOTE
Originally posted by krsna77

I have a tendency to believe you, however, I can think of one specific example (Alice in Chains - Dirt), that does clip very terribly, with nasty distortion, in OGG and MP3, until I normalize at ~0.84 (for MP3 - tho I use this value for OGG, its threshold may in fact be higher). Then it sounds fine (of course, I think this album really is pushed to the very limits).


Can you make a sample available? I would like to look at it.

QUOTE

Know of any good apps that can count clipped samples, so I can visually compare with what my ears are telling me?...


Sound Forge and probably Cool Edit can do this.

--
GCP
Go to the top of the page
+Quote Post

Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 30th August 2014 - 21:48