IPB

Welcome Guest ( Log In | Register )

is Ogg Vorbis the best Lossy encoder? (what is?)
snadge
post Jun 8 2011, 04:01
Post #1





Group: Members
Posts: 32
Joined: 5-March 11
From: UK
Member No.: 88709



ive been trying to find out which encoder produces the best audio quality at similar bitrates (say 128k) to other lossy encoders - ive seen a couple of reviews and tests and they seem to point to Ogg Vorbis as being the better encoder - I encoded a WAV file to MP3, AAC, WMA & Vorbis all at 128k CBR and while it was hard to tell any difference the Ogg Vorbis was pumping out higher frequencies at 20Khz + and the rest were up to 18Khz (according to spectrum on Foobar2000)

the only gripe is during conversion Ogg Vorbis was the only one that didnt have the Tag info from the WAV file.

can anyone lead me to more listening test results and the likes so i can ascertain for myself? - i would like others views on "best lossy codec" etc

I read on Wikipedia that AAC at 128k is supposedly Transparent to the lossless source according to listening tests by M-PEG for ITU or something? - I was hoping to adopt AAC as my default rip codec as I have an iPod and MP3 player that plays AAC - but Iam in the market for a new media-player so all this is irrelevant as I can buy something to suite.

thanks in advance for replies smile.gif

please be gentle...im a noob at all this,

This post has been edited by snadge: Jun 8 2011, 04:17


--------------------
www.dslbuddy.net - Broadband Tech Support
Go to the top of the page
+Quote Post
 
Start new topic
Replies
Xanikseo
post Jun 12 2011, 14:07
Post #2





Group: Members
Posts: 27
Joined: 14-April 09
Member No.: 68951



QUOTE (dv1989 @ Jun 10 2011, 01:30) *
Quality setting being equal, from the encoder having to allocate more bits to encode a particular source file, it does not follow that the resulting lossy file is any farther removed from its source than is a file of a lower bitrate from its source. It simply means the encoder judged it required more bits to attain the same (approximate) quality. Thatís the entire point of settings based on quality rather than bitrate, after all!

Ok that is true, but it is reassuring that the encoder needed fewer bits to handle a particular sample: it's a sign that it can be approximated more efficiently with the encoder used, which is a good thing, rather than something to be worried about. That was my main point.

QUOTE (dv1989 @ Jun 10 2011, 01:30) *
Way off track, though thereís little point going into great depth (as if I even could!) when thereís bound to be plenty of documentation on VBR explaining its actual rationale. But in short: The best lossy encoder in the world would still benefit from a VBR model because all passages of audio are not created equal. It has nothing (necessarily) to do with inherent incompetence of either the encoder or its format as a whole.

Of course, the whole point of music is that it isn't just one sine wave for about 5 mins, in fact CBR is a pretty dumb idea, apart from the fact that it is the easiest to implement, and you know exactly what the filesize will be in the end.

When I say deficiencies I mean, say for example the encoder can only represent everything sinusoidally, it would not be able to represent a square or triangle wave in terms of sinusoidal waves, so it would have to increase the bitrate to accurately represent that, but if the encoder didn't have that deficiency and could just switch to representing things in square waves, it would not have to increase the bitrate at all. So in a way, VBR tends to be a cheap work around of sorts, as I'm pretty sure a lot of the variation in bitrate could be removed if more flexible algorithms were introduced into the encoder. Therefore in today's context, a higher resulting output bitrate is the sign that it is more likely that there is a part of the music that the encoder can't handle very well with it's current algorithms, which means it's more likely part of the music was not as accurately represented. But as you mention, a perfectly flexible encoder would still have a VBR, as the music itself has varying complexity, but vorbis is not an infallible perfectly flexible format.

QUOTE (dv1989 @ Jun 10 2011, 01:30) *
Sounds like ABR to me, your aforementioned misconception notwithstanding.

Yes VBR is when one specifies a quality. Quality is dependant on how well the codec can handle the music per bitrate.

effectiveness of encoder (0-1) = (overall perceived quality)*(1-(compression ratio)) ; 0 < overall perceived quality < 1 (lossless or transparent, depending on the encoder's aim), 0 < compression ratio=(uncompressed filesize)/(filesize) < 1
so in other words, a perfectly effective encoder is lossless/transparent and compresses the file into nothing.

=> overall perceived quality = (effectiveness of encoder)/(1-(compression ratio))
Which works for either the whole file, or just a sample of it.

Therefore, since the quality is to be a specified constant, if the bitrate decreases and compression ratio also decreases, the effectiveness of encoder is higher. Which is basically just a mathematical way of saying what I said in my first sentence. Given the encoder seems more effective for a particular sample, it is a sign that the type of sample has been well thought of in the design of the codec, and is less likely to be an inaccurate approximation.

I think of ABR as just a more restricted form of VBR, based on the assumption that each person only has enough space on their DAP for one music file. The thing about vorbis is, the quality settings are pretty much target bitrates, just that the encoder is much more forgiving to itself, and allows itself to deviate much more from the target per file, as after an infinite number of files, the files will tend towards the target bitrate, due to the heterogenous nature of music which you meantioned. So actually, vorbis is trying to get towards a target bitrate, just in a cleverer way, as there will be a standard distribution of bitrates, with the mean being the target bitrate. So when it sounds like ABR, it is, just a lot cleverer, as the main aim of an encoder is to be more effective by decreasing the compression ratio for a given quality. So cutting back on the bitrate when possible is intrinsically part of VBR, not just ABR.

QUOTE (dv1989 @ Jun 10 2011, 01:30) *
As have the VBR algorithms of all the leading audio codecs. Again, it has nothing to do with intrinsic deficiencies of lossy audio encoding. VBR just is logical given the heterogenous nature of most source material. It makes sense that end-users would prefer oscillating bitrate to disruptive changes in quality.
I know and agree.

I feel we're on the same page, you just misunderstood me.

Wow I've just realised how much I've written, I seem to be repeating myself a lot, maybe I should be some boring lecturer tongue.gif.
Go to the top of the page
+Quote Post
saratoga
post Jun 12 2011, 18:10
Post #3





Group: Members
Posts: 4853
Joined: 2-September 02
Member No.: 3264



QUOTE (Xanikseo @ Jun 12 2011, 09:07) *
When I say deficiencies I mean, say for example the encoder can only represent everything sinusoidally, it would not be able to represent a square or triangle wave in terms of sinusoidal waves,


This is a really unfortunate example given that a digital square is exactly defined by a few sin waves.

QUOTE (Xanikseo @ Jun 12 2011, 09:07) *
So in a way, VBR tends to be a cheap work around of sorts, as I'm pretty sure a lot of the variation in bitrate could be removed if more flexible algorithms were introduced into the encoder.


No this is nonsense. The instantaneous entropy of audio varies continuously and randomly. If it didn't you'd just be listening to static . . .

Go to the top of the page
+Quote Post

Posts in this topic
- snadge   is Ogg Vorbis the best Lossy encoder? (what is?)   Jun 8 2011, 04:01
- - SonicBooom!   I hope I'll not get bashed for I am not truly ...   Jun 8 2011, 04:36
- - snadge   thanks for the info im glad you told me about re...   Jun 8 2011, 04:58
- - terhardp   I'm saying this from my personal view, not bas...   Jun 8 2011, 07:10
|- - snadge   QUOTE (terhardp @ Jun 8 2011, 07:10) I...   Jun 8 2011, 17:32
|- - saratoga   QUOTE (snadge @ Jun 8 2011, 12:32) I play...   Jun 8 2011, 18:52
|- - snadge   QUOTE (saratoga @ Jun 8 2011, 17:52) QUOT...   Jun 9 2011, 14:03
|- - DonP   QUOTE (snadge @ Jun 9 2011, 08:03) [ he i...   Jun 9 2011, 15:26
- - googlebot   What is the best car?   Jun 8 2011, 07:43
|- - Lorem Ipsum   The Batmobile.   Jun 8 2011, 08:07
|- - Cron   QUOTE (googlebot @ Jun 8 2011, 08:43) Wha...   Jun 8 2011, 08:10
- - smok3   if planing to rockbox, i would check battery eatin...   Jun 8 2011, 19:15
- - C.R.Helmrich   @ snadge: regarding quality, have a look at http:/...   Jun 8 2011, 19:45
- - Xanikseo   Regarding that link, it's only really useful f...   Jun 8 2011, 22:03
|- - Canar   QUOTE (Xanikseo @ Jun 8 2011, 14:03) Howe...   Jun 8 2011, 22:56
- - snadge   thanks for all the great replies... so, do you th...   Jun 9 2011, 13:43
- - lvqcl   Dynamics? What is it?   Jun 9 2011, 13:49
|- - snadge   QUOTE (lvqcl @ Jun 9 2011, 12:49) Dynamic...   Jun 9 2011, 13:56
|- - pdq   QUOTE (snadge @ Jun 9 2011, 08:56) QUOTE ...   Jun 9 2011, 14:25
- - Xanikseo   QUOTE (pdq @ Jun 9 2011, 14:25) QUOTE (sn...   Jun 10 2011, 01:00
|- - dv1989   QUOTE (Xanikseo @ Jun 10 2011, 01:00) QUO...   Jun 10 2011, 01:30
- - smok3   QUOTE (DonP @ Jun 9 2011, 16:26) QUOTE (s...   Jun 10 2011, 07:10
|- - DonP   QUOTE (smok3 @ Jun 10 2011, 01:10) QUOTE ...   Jun 10 2011, 12:44
|- - saratoga   QUOTE (smok3 @ Jun 10 2011, 02:10) QUOTE ...   Jun 10 2011, 15:32
- - smok3   saratoga, andless is working with my old musepack ...   Jun 12 2011, 11:02
- - Xanikseo   QUOTE (dv1989 @ Jun 10 2011, 01:30) Quali...   Jun 12 2011, 14:07
|- - saratoga   QUOTE (Xanikseo @ Jun 12 2011, 09:07) Whe...   Jun 12 2011, 18:10
- - dv1989   While your post is considered and doesnít look par...   Jun 12 2011, 17:16
- - Xanikseo   I do accept that vbr is necessary, music does cons...   Jun 12 2011, 20:08
|- - saratoga   QUOTE (Xanikseo @ Jun 12 2011, 15:08) Whe...   Jun 12 2011, 21:09
- - Xanikseo   I meant what kind of signal would represent a prob...   Jun 13 2011, 00:09
- - [JAZ]   @Xanikseo: While everything is representable by se...   Jun 13 2011, 09:46
|- - saratoga   QUOTE ([JAZ] @ Jun 13 2011, 04:46...   Jun 13 2011, 17:14
- - Xanikseo   I never said that you should use a square waves as...   Jun 15 2011, 23:20
- - K-Meleon   @OP: This test shows that 96 kbps QuickTime AAC is...   Jun 16 2011, 07:25
- - B7k   QUOTE (K-Meleon @ Jun 16 2011, 02:25...   Jun 27 2011, 06:47


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: 25th July 2014 - 16:04