Bitrate relation at transcoding from MP3 to AC3

your post is a little hard to follow, so please bare with me if i make a few mistakes.. dd = dolby digital, which is generally how people refer to ac3. adobe is a good ac3 encoder i believe. you wont keep all your quality from the 320 mp3, so you could drop the bitrate slightly, but anything above 250ish should be unnoticable even transcoding.

immy basushi thanx for reply. If I right understand I can litle drop bitrate from MP3 to AC3 without quality loss. For 320kb/s CBR MP3 enough 256kb/s AC3 Dolby Digital 2.0. With kind regards yup.

stephanV :) Best way decode as wav without compression, or may be Dolby Digital 2.0 448kb/s enough? yup.

well, decoding to wav would give you an enormous file size so i wouldn't do that. just encode to 256kbps AC3 Dolby Digital 2.0 and see (listen i guess :D) if you find the sound acceptable. if you do, then thats fine. if you don't then try a higher bitrate. what is acceptable is quite subjective: best way is to judge that for yourself. I can tell you 256 kbps sounds like cr4p (which i actually don't know, I've never tested it), but you shouldn't believe me or anyone when they make such claims out of the blue. I'm already quite happy with +/-192 kbps MP3 (for most music at least), which maybe other people find horrible. there are no ears like your own. after all, you are going to be the one who has to listen to it. ;)

stephanV that means cr4p. yup.