Which AAC encoder is used in VRD?

[musicvid]

Just curious, the 5.1 output from AC3 5.1 DVDs is surprisingly good!

 

[Dan203]

We're currently using the Main Concept AAC encoder. It's actually the last MC encoder we're using. Mainly because, last time we looked, FFMpeg didn't support LATM properly.

 

[musicvid]

ffmpeg doesn't sound as good, either.

 

[richardpohl]

Hello, when I try to set the AAC sound 512kbs, it works, but when I save this setting as a new profile, it always switches to 448, and does not save the 512 settings. In the end, I have to rewrite it each time I save. Is it a bug?

 

[richardpohl]

 

[jmc]

Hello, when I try to set the AAC sound 512kbs, it works, but when I save this setting as a new profile, it always switches to 448, and does not save the 512 settings. In the end, I have to rewrite it each time I save. Is it a bug?

Tools>"Manage Output Profiles..." - Changes made here should stick.
Changes made while "saving" will not stick.

Audio can be a bit weird...
If I remember correctly, "Transitions" always changes my 192k ac3 to 256k ac3.

 

[richardpohl]

I just tried, still the same problem. I write 512 and save, but it becomes 448 next time I try to use that profile.

 

[richardpohl]

Actually, 512 is not even a selectable option, it needs to be written in (but it works, I checked the Mediainfo).

 

[Dan203]

The technical limit of AAC is 6.0 * channels * sample rate or 1024 whichever is lower. However we don't have access to all that information in the profile dialog unless you explicitly set it so we have to make some assumptions. So we limit the value to 448 in the actual profile as a safe maximum. As you discovered you can override it once, in the save dialog, but it will not stick due to the rules logic that governs the dialog.

 

[musicvid]

There is a rule of diminishing returns with any lossy encoder. 5.1 AAC at 448 Kbps is above the shoulder of that curve, so measurable gains at 512 Kbps are insignificant.