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AC3 5.1 to AAC 5.1 Suitable Mode/Profile/Bitrate?
post Jun 21 2012, 15:25
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I have a large number of 5.1 AC3 audio file encoded at CBR 384 kbps that i want to transcode to AAC. Channel mapping is not a problem. Bytes are scarce, so my goal is to minimize bitrate while preserving audio transparency.
Now i've read in various online posts that AAC standards recommend around 260 kbps for 5.1 audio. I'm using a certain application (i'm not interested in suggestions of using another one or another encoder for that matter) that uses up-to-date AAC codecs. This application gives me the option of encoding in CBR AAC (bitrate ranging from 4 to 448 kbps in increments of 4, and profiles HE2/HE/LC are completely user selected) and VBR AAC (where i can choose a quality preset from 1 to 5, 5 being highest quality and largest filesize and where profile is strictly automatic, HE-AAC 2 kicks in when using Q1, HE-AAC when using Q2, and from Q3 to Q5, format profile is LC).

Giving all the above, and knowing that audio transparency and quality is usually subjective, what would be a good option?
My initial preference is using VBR Q3/LC which gives me 5.1 audio files encoded at around 250 ~ 300 kbps. Do i need to go higher?? Can i go lower without losing perceptive quality?? Should i consider lower CBR with HE profile??

Waiting for some suggestions. Thank you.
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post Jun 26 2012, 15:55
Post #2

Group: Members
Posts: 28
Joined: 21-June 12
Member No.: 100878

Wow... The hostility on this forum is crazy.. Second time registering here, and it seems just like the first time, i might take a long hiatus again!!
All i'm asking for is the opinion of some more experienced users regarding some matters and it's always "why do u want to do dat?" and "listen and figure it out"...
I can't for the life of me understand this collective need of withholding knowledge. I mean it goes without saying that one should do some testing of his own, but is it this hard to ask for people to share their experiences too?? That's all i'm asking for, if you happen to have an opinion on this issue, or some past experiences, drop a recommendation. No one's gonna hold you up to it.

There is nothing bizarre about my question, and it is not a matter of time. I'm not trying to shortcut my way into taking a decision. On the contrary, i've done some extensive testing, but i'm not in a hurry, and would like to factor in some others' recommendations into my final decision.

So here, let me try this again:

Let's say i have a 5.1 AC3 audio file encoded @ 384 kbps. Now let's say i want to edit some silence in and out of this audio track, then re-encode it to the same format (5.1 AC3). What would be the "most logical" bitrate setting to use? Would it usually be enough to stay @ 384 kbps, or is there a need to go higher?? Would going higher then 384 kbps in this case be a waste of space??
Not asking for anyone to spend their time doing listening tests on my behalf. Just share what you think or if you have some past experience and that's all.

That's the whole point of lossy encoding. To achieve highest quality at lowest bitrate possible. And to rely solely on my current subjective listening experience is a flawed logic. That's why i put my trust in some more experienced users in this forum, for the second time around.

Thank you.
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Posts in this topic
- Makaveli7184   AC3 5.1 to AAC 5.1 Suitable Mode/Profile/Bitrate?   Jun 21 2012, 15:25
- - probedb   Do some tests and find out. You're going from ...   Jun 21 2012, 16:02
- - Makaveli7184   Well, i appreciate your input, but that's not ...   Jun 21 2012, 16:39
- - onkl   5.1 AC3 with only 384 kbps is already quite low. I...   Jun 21 2012, 22:00
- - Makaveli7184   Well, let's say that i wanted to convert an or...   Jun 25 2012, 20:29
|- - saratoga   QUOTE (Makaveli7184 @ Jun 25 2012, 15:29)...   Jun 26 2012, 02:44
|- - Makaveli7184   QUOTE (saratoga @ Jun 26 2012, 01:44) QUO...   Jun 26 2012, 03:05
|- - probedb   QUOTE (Makaveli7184 @ Jun 26 2012, 03:05)...   Jun 26 2012, 08:03
- - saratoga   If you're just doing it for fun, might as well...   Jun 26 2012, 04:05
- - Makaveli7184   Wow... The hostility on this forum is crazy.. Seco...   Jun 26 2012, 15:55
- - onkl   Lossy to lossy is ugly and not so advanced formats...   Jun 26 2012, 16:14
|- - jetpower   QUOTE (onkl @ Jun 26 2012, 17:14) Simple ...   Jun 26 2012, 17:30
|- - john33   QUOTE (jetpower @ Jun 26 2012, 17:30) QUO...   Jun 26 2012, 17:40
- - john33   When decoding a lossy audio file, the content that...   Jun 26 2012, 17:34
|- - Makaveli7184   QUOTE (onkl @ Jun 26 2012, 15:14) Lossy t...   Jun 26 2012, 18:35
- - Makaveli7184   Also, is there a decent "DelayCut" equiv...   Jun 26 2012, 18:39
- - onkl   MP3directcut which can also do fading, so somethin...   Jun 26 2012, 18:45
|- - Makaveli7184   QUOTE (onkl @ Jun 26 2012, 17:45) MP3dire...   Jun 26 2012, 19:04
|- - Dynamic   QUOTE (Makaveli7184 @ Jun 26 2012, 18:04)...   Jun 28 2012, 07:03
- - Makaveli7184   Thanks for everyone who contributed in this thread...   Jul 10 2012, 20:03

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