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Topic: Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S (Read 4747 times) previous topic - next topic
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Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Hi folks normaly im not into Audio that much but for doing Video Compression with Audio you also have to take this part into account (to save overall bitrate), so recently i did a test of my own about transparency and Quality off Encoders as i have no Surround System here my tests where soley based on Stereo and there was no reall difference audible for me between Nero's Encoder and Apple' latest Itunes Encoder, i thougt.
To be absolutely sure i send samples of the encoding tests (Terminator Theme, Star Wars Theme) to a Friend of mine and he listened on his Dolby Surround System the test was done with different bitrates and allways one problem was audible for my friend with the Nero Encoder, the back channels where allways duller then with the Itunes Encoder. I couldn't here this as i said Stereo but he allways heared it with the Nero Encoded files and Itunes was fine ? Is this a Bug or is Itunes better optimized for Dolbys Surround Decoders, is it a known (Quality) problem ?

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #1 –
Please read the forums terms of service, in particular number 8, they will help you understand why noone will be able or willing to answer a "question" such as this.

PS. I no longer work for Nero.

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #2 –
Sorry Garf for violating the TOS i see but i think a blind test is not needed for this type of Problem, if someone does the same test on his (Dolby Surround) system (Nero Devs) or another user and it would be the same, then at least it would be true that the back channels are duller with Nero's Encoder then, whats this couseing is then up to the devs to find out. If someone is willing to conduct a ABX for this would be nice im not sure if i find the time @ the moment.

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #3 –
Well, the iTunes AAC encoder can only output stereo AAC files.  Unless you are using a feature in QuickTime pro or some other Apple movie editing software, then the files you are testing are stereo and the Dolby surround system is probably using Dolby Pro Logic II.

A ABX test is needed though.  I have a 5.1 surround sound system and will try to conduct one using Nero's latest AAC encoder and the iTunes AAC encoder (if I can figure out how to encode in 5.1 with the iTunes AAC encoder).

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #4 –
@kornchild2002
The system my friend is useing is a SONY STR-DE315 and according to him only Pro Logic not Pro Logic 2. The test was done with Stereo only no 5.1 but on his config, he says the back channels sound better with Itunes Encoded files (more dynamic) then they do with Nero's Encoded ones (duller).

It's also strange that with Nero's Encoder it's very hard to hit the correct bitrate with CBR/BR on the StarWars sample if i use -cbr 131072 i endup with 134 kbps, if i use -cbr 128000 i endup @ 131 kbps, hmm with -br 128000 it's 129 kbps and with -br 131072 it's 132 kbps.
As somebody else allready mentioned in another thread here http://www.hydrogenaudio.org/forums/index....showtopic=50850 every encoding process results in a different CRC with the same settings, i can confirm this.

Code: [Select]
CBR 

Nero
-----
Codec                : AAC LC
Spielzeit            : 5min 27s
Bitrate              : 129 Kbps
Kanäle               : 2 Kanäle
Samplingrate         : 44 KHz
StreamSize           : 5281402
  
Itunes
------
Codec                : AAC LC
Spielzeit            : 5min 27s
Bitrate              : 128 Kbps
Kanäle               : 2 Kanäle
Samplingrate         : 44 KHz
StreamSize           : 5241620

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #5 –
May I suggest you to use shorter sentences, replace some of your commas by dots, and add a few dots where needed?
This would greatly improve readability of your posts.

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #6 –
As for the difference between stereo iTunes and Nero files being played on 5.1 system - I really have no idea what could cause the difference without original, encoded samples and ABX results from your side - if you are willing to provide that, we'll definitely take a look at it.

Speaking of the bitrate - if you use -cbr switch the bit rate should be perfectly within ISO-AAC limits - meaning, average bit rate + ISO bit reservoir size - maybe the tool used for printing out the bit rate is wrong.

Ivan, Menno and Garf please read Nero AAC May Encoder BUG with Dolby S

Reply #7 –
@Gabriel
Yes, sorry im sometimes in a hurry 

@Ivan Dimkovic
Im gonna do a placebo test with him today, to see if he really is hearing that "dull back channels".
Is it correct if i assume that Itunes writes a tagg for the selected bitrate and allways reads that first ?, because if i select 96 kbps VBR Itunes allways shows me 96 kbps as the final bitrate, but other programms show higher bitrates for the Main Stream for those VBR files .
It seems Nero doesn't do this and so bitrates displayed are actually the original final VBR ones inside every application i prefer that actually over Itunes "selected bitrate cheat tagg" .
Yep Nero CBR also shows 128 kbps in Itunes itself, but that differs by some programms by (rounding) values that are 1 kbps over (target bitrate) for the Nero encode see picture bellow.