6 or 2 Channel AC3 To 2-Ch Conversion

[neo_anderson]

hi,
as i do not have a surround sound 5.1 system, so pls can u guys recommend me which way is good for my ac3 movie soundtracks (5 or 2 ch) to be converted to 2-ch, i mean which is the better way, ogg,mp3 or aac? which is recommended by the experts and memebrs of doom9 forums? or , should i just use ac3 filter for it 2-ch downmix?

[Kurtnoise]

ac3 stereo...It's even noticed in the FAQ !!!

[neo_anderson]

Originally posted by Kurtnoise13
ac3 stereo...It's even noticed in the FAQ !!!
This means i should keep the ac3 stream, and not convert it to some other format, right? still , pls tell me if i convert, which is the better option? pls bear with me for such questions, pls!

[ursamtl]

If you have a Dolby Pro Logic (I or II) decoder in your playback system, any 5-ch AC3 material will be downmixed automatically, and of course a 2-ch will work perfectly. In such a case, there's nothing you need to do. The only thing you'll lose is the LFE channel (if a soundtrack is 5.1 and contains information in the LFE channel). Dolby decoders simply ignore the LFE when they do this process, which they call "folding down."

Regards,
Steve.

[neo_anderson]

actually i was looking forward to muxing the audio stream in mp4 container or mkv container, with mpeg-4 encoded movie file, so for that reason, i was asking for recommendations towards transcoding!

[Kurtnoise]

Well...it depends of what you want exactly. If you have the choice between ac3_6ch and ac3_2ch and if you don't care about the final size of your backup, then I would suggest you to keep the ac3 stereo stream as I said.

Therefore, if you want to keep your backup in 1 cd by example, well I would recommend you to transcode your file in vorbis/aac/mp3 from the ac3 stereo. Thus, if you want to maximize the video part, sound like he-aac could be great. Anyway, if you want to keep a certain good level for the audio part, try vorbis at q=4 or lc-aac at 192 kbps.

[neo_anderson]

thanks a lot kurt and ursamtl !