AAC question

[azfarhus]

I am using mediacoder and want to use AAC as audio stream. It has three AAC profiles i-e LC-AAC, HE-AAC and HE-AACv2. My question is that which one is main profile among them and among them which one is best (I don't care of size much).

My another problem is that I want to fix audio bitrate to 128k but if I use LC-AAC is goes above it around 170k+ and if I use AAC-HEv2 it goes down to 60-70k (tough I have set 128k and CBR)

Here you can see the results.

Audio
ID                               : 101
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : LC
Codec ID                         : 40
Duration                         : 8mn 43s
Bit rate mode                    : Variable
Bit rate                         : 172 Kbps
Maximum bit rate                 : 235 Kbps
Channel(s)                       : 2 channels
Channel positions                : Front: L R
Sampling rate                    : 44.1 KHz
Compression mode                 : Lossy
Stream size                      : 10.8 MiB (8%)
Encoded date                     : UTC 2011-01-31 10:40:34
Tagged date                      : UTC 2011-01-31 10:40:34

Audio
ID                               : 101
Format                           : AAC
Format/Info                      : Advanced Audio Codec
Format profile                   : HE-AACv2 / HE-AAC / LC
Codec ID                         : 40
Duration                         : 8mn 43s
Bit rate mode                    : Variable
Bit rate                         : 64.0 Kbps
Maximum bit rate                 : 68.4 Kbps
Channel(s)                       : 2 channels / 1 channel / 1 channel
Channel positions                : Front: L R / Front: C / Front: C
Sampling rate                    : 44.1 KHz / 44.1 KHz / 22.05 KHz
Compression mode                 : Lossy
Stream size                      : 3.99 MiB (3%)
Encoded date                     : UTC 2011-01-30 11:15:04
Tagged date                      : UTC 2011-01-30 11:15:04

[PuzZLeR]

Audio compression from worst to best is:
AAC-LD -> AAC-HE -> AAC-HE v2
Better compression means better quality for same bitrate, or lower bitrate for similar quality.

There is no "main" profile that I have heard of with AAC. Each variant is an extension/improvement of the previous one and each lower order variant is a complete subset of the higher one in features.

However, the compatibility among devices is in reverse. And, AFAIK, anything that accepts whatever variant of AAC should also accept any lower variant of it as well.

I do notice lately that many devices now accept AAC-HE finally, when a few years ago this wasn't so. I assume AAC-HE v2 will be following in the same path too in the near future.

I would avoid any audio encoding that is not CBR. Problems have historically arisen.

As far as MediaCoder is concerned, quite frankly, it's a flaky app and sucks. Many times it decides to not work, or gives you a different result than what you ask. I don't know why and I don't care.

Personally, I do all my AAC encoding with Nero's AAC codec (with the AAC-HE profile mostly). It's fast, reliable, compatible and high quality. You can download it from Nero free and you can use it in several GUIs, such as MeGUI (once you load it in the directory and set the path).

[ricardouk]

Personally, I do all my AAC encoding with Nero's AAC codec (with the AAC-HE profile mostly). It's fast, reliable, compatible and high quality. You can download it from Nero free and you can use it in several GUIs, such as MeGUI (once you load it in the directory and set the path).

Or Lamexp