HydrogenAudio

Lossy Audio Compression => AAC => AAC - General => Topic started by: jianxin yan on 2002-08-14 15:56:35

Title: how to get constant bitrate for psytelaac?
Post by: jianxin yan on 2002-08-14 15:56:35
hi
    who know how to set up psytel aac in order to get constant bitrate?


thanks
Title: how to get constant bitrate for psytelaac?
Post by: rjamorim on 2002-08-14 16:14:13
Quote
Originally posted by jianxin yan
who know how to set up psytel aac in order to get constant bitrate?


There are some hidden switches to turn off using the bit reservoir, and some other tricks to get CBR AAC.

But why do you want that anyway? Quality tends to get worse in CBR.
Title: how to get constant bitrate for psytelaac?
Post by: jianxin yan on 2002-08-14 16:20:35
hi
  i wish to compare aac with wma9 at canstant bitrate.
becuase wma9 can get very right canstant bit rate, so i hope to compare them at same conditions.

  do you know how to set those hidden switchs?

regards.
Title: how to get constant bitrate for psytelaac?
Post by: rjamorim on 2002-08-14 16:37:12
Quote
Originally posted by jianxin yan
do you know how to set those hidden switchs?


You can try searching them here:
http://www.hydrogenaudio.org/forums/showth...=6860#post21966 (http://www.hydrogenaudio.org/forums/showthread.php?s=&postid=21966&t=6860#post21966)

I'm not feeling that courageous today.
Title: how to get constant bitrate for psytelaac?
Post by: wildboar on 2002-08-14 19:44:55
Quote
Originally posted by jianxin yan
i hope to compare them at same conditions.


"Same conditions" as opposed to letting the encoder do what it was designed to do, then making an evaluation, is a fallacy.
Title: how to get constant bitrate for psytelaac?
Post by: ezra2323 on 2002-08-15 03:25:57
Use this link  http://home.wanadoo.nl/~w.speek/ivan&menno.htm (http://home.wanadoo.nl/~w.speek/ivan&menno.htm). Download this program, run it, and select 128 or 128- production to encode. They are CBR settings.
Title: how to get constant bitrate for psytelaac?
Post by: rjamorim on 2002-08-15 04:32:18
Quote
Originally posted by ezra2323
Use this link  http://home.wanadoo.nl/~w.speek/ivan&menno.htm (http://home.wanadoo.nl/~w.speek/ivan&menno.htm). Download this program, run it, and select 128 or 128- production to encode. They are CBR settings.


Hummm... I would believe he wants REAL CBR. The -br switch in AACenc generates some kind of ABR that only Ivan can understand. :-/
Title: how to get constant bitrate for psytelaac?
Post by: Joe Bloggs on 2002-08-15 07:20:36
It seems obvious to me that AAC was not designed with 'Real' CBR in mind. In that case forcing it to do 'Real' CBR would probably degrade the results a lot?
Title: how to get constant bitrate for psytelaac?
Post by: rjamorim on 2002-08-15 08:01:35
Quote
Originally posted by Joe Bloggs
It seems obvious to me that AAC was not designed with 'Real' CBR in mind. In that case forcing it to do 'Real' CBR would probably degrade the results a lot?


I'd rather say "Allowing ABR would increase the quality of results a lot"
Title: how to get constant bitrate for psytelaac?
Post by: Ivan Dimkovic on 2002-08-15 09:57:06
No.. AAC can have "pure" CBR - FhG encoders generate file of, say, 128000 bps  bitrate - exact in a bit! 

But that requires heavy modifications in the codec, and - this way the quality could be a little bit higher
Title: how to get constant bitrate for psytelaac?
Post by: jianxin yan on 2002-08-16 15:05:55
hi, ivan

  how about your aac codec?

  could you give some switches for pure cbr setting?



regards.
Title: how to get constant bitrate for psytelaac?
Post by: Joe Bloggs on 2002-08-16 18:07:47
Quote
Originally posted by Ivan Dimkovic
and - this way the quality could be a little bit higher


Just to clarify, in case anybody isn't reading this right--'this way' stands for doing ABR instead of CBR

I feel all weird 'clarifying' other people's posts for them, but I don't think I can go wrong here and I have this compelling, um, compulsion to clarify for some reason