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Topic: SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps (Read 525 times) previous topic - next topic
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SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps

Hello. In this reply, it's seen that Fraunhofer IIS' xHE-AAC encoder stops using SBR at 72kbps. This makes sense, because SBR is only recommended for below 80kbps in non-xHE AAC, and this level should be lower for xHE-AAC since its core coding is different too; but I detected that in the newest version EZ CD Audio Converter SBR is used all the way up to 96kbps (I also checked with 48kHz). This sounds ridiculous to me, and I don't think it needs explanation. Any opinions about this or ideas as to why did this happen? And, where can I find SBRless xHE-AAC files of these bitrates for inspection (preferably together with other bitrates too as there is probably encoder difference too)? @guruboolez I'm pinging you because the linked reply is posted by you.

Re: SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps

Reply #1 –
Write to Poikosoft (see https://www.poikosoft.com/contact ), it is a mistake, SBR should be used up to 36 kbps in mono VBR (56 kbps in CBR), up to 40 kbps in stereo VBR with PS, up to 64 kbps in stereo without PS, both in CBR and VBR.

In my opinion the maximum limit is in CBR with SBR for bitrates lower than 64 kbps in mono or 72 kbps in stereo, in VBR for bitrates lower than 48 kbps in mono or lower than 64 kbps in stereo with PS, lower than 96 kbps without PS. But it would be an exaggeration to keep at bay the requests of other users more demanding on numbers than on the sound obtained.

Re: SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps

Reply #2 –
Quote from: celona on
Write to Poikosoft (see https://www.poikosoft.com/contact ), it is a mistake, SBR should be used up to 36 kbps in mono VBR (56 kbps in CBR), up to 40 kbps in stereo VBR with PS, up to 64 kbps in stereo without PS, both in CBR and VBR.

In my opinion the maximum limit is in CBR with SBR for bitrates lower than 64 kbps in mono or 72 kbps in stereo, in VBR for bitrates lower than 48 kbps in mono or lower than 64 kbps in stereo with PS, lower than 96 kbps without PS. But it would be an exaggeration to keep at bay the requests of other users more demanding on numbers than on the sound obtained.

Thank you though I think this answer is rather mazy and probably containing some mistakes, but in this page poiko said "All formats supported by the xHE-AAC encoder are listed in xHE-AAC configuration." which was unrealistic from the beginning and now I also remembered this reply of yours - what the heck?

Re: SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps

Reply #3 –
I believe that the most exotic sampling frequencies only exist to fit within a certain bitrate. For practical purposes today 24 kHz sampling is almost never used because some DACs do not like it, and the choice outside the telephone field is reduced to only 3 bitrates, 32 kHz, 44.1 kHz (which will lose meaning over time) and 48 kHz.

Do not consider my messages from three or more years ago, I am an early adopter, for example about Opus I wrote the worst infamies (I say this jokingly), at the beginning I did not like it, little by little it improved and perhaps I understood better where the project was going and today it is one of my favorites for speech. Time forces us to update our opinions.

Also on Exhale I made tables to show the inconsistencies in the use of the bitrate for each combination of bit, kHz, mono or stereo, etc. and today it is much more linear and predictable, but I do not use it for speech (I bought a paid encoder), nor for music.

Maybe for the use you want to make of it the Fraunhofer xHE-AAC encoder does not make much sense, to hear the music well you have to go up to bitrates very similar to those of AAC-LC and therefore you will not find great advantages.

I do not think that stubbornness to stay within a certain bitrate will repay you in the future for the effort and time you are spending. Use AAC-LC and don't care, you will not have SBR in your compressed files, the important thing is to be satisfied with the content. You will not throw away the uncompressed files anyway.

Now you know why I am not very present here, I love our paranoia, but in the end they lead to almost nothing.

Re: SBR usage of xHE-AAC at 72kbps, 80kbps, and 96kbps

Reply #4 –
Thanks. But I'm experimenting with xHE-AAC just because I'm curious, I'm not planning to use it. More than one devices that I use accept only MP3 and WMA as lossy codecs anyway, and I even use the same MP3 files on computers and computer-like devices (e.g. a smartphone) because it is easier for me though this may change. (I prefer MP3 because I don't feel that WMA is really estabilished.)