ac3 bitrate for 5.1

[gavogavo]

I have a ac3 that i want to fit but it has to be no more then 224kb. Should I downsample from 5.1 to 2.0. As that bitrate to low for 5.1 or will it sound ok with 224kb. ac3 needs higher bitrates then others.

[Blue_MiSfit]

Yes, you should definitely downmix to 2ch, which will retain full frequency response at 192kbps or higher.

5.1ch needs at least 384kbps to sound good, and 448kbps to have full frequency response. 224kbps for 5.1ch will heavily lowpass (remove high frequencies).

DDP on the other hand (E-AC3) can be full-range at 224kbps IIRC, and AAC certainly can ;)

~MiSfit

[MatLz]

Hi Gavogavo.
You can downsample the samplerate of your ac3 to 32khz or 24khz if you want change the bitrate to 224kbps, this method will reduce the lowbitrate artifacts but it will cause a loss of the dynamic.
Or you can convert it in aac without resampling.

[gavogavo]

cant use aac in xbmc takes up way to much cpu power... Maybe ogg at 5.1..

[MatLz]

So try to downsample your ac3! You've got nothing to loss, except some minutes to test that. And if the quality is good at your ears...

[Blue_MiSfit]

Ogg isn't very good in multichannel IIRC.

I'd say 2ch AC3 is a good way to go.