downsampling ac3 to ac3 ???

[mcp]

Hi freaks, I would like to know if somebody could tell me a program to downsample an ac3-stream to an ac3-stream to make it a little "smaller".
Anyone here knows something good? (perhaps for *.dts , too??? )
:D

[jdobbs]

The only way I know to do it is to convert it to a .WAV file (using AZID, AC3DEC, or DVD2AVI) then reencode at a lower bitrate with SoftEncode.

[jeffnoone]

there are several options:

if original is 6 channel and you want to preserve 6 ch, then you must import the 6 channel .ac3 into softencode, it will decode this into SIX large wav files as intermediary step (NB have many GB free on designated drive), and you can then re-encode at lower bit rate but maintain 6 channel

if it is only 6 channel source (and no 2 channel on DVD)and if you are happy with 2 channel AC3 output, proceed as per jdobbs reply. Don't forget to tick dolby surround in Softencode

THere may also be a downmix function in softencode (eg import 6 channel ac3, export 2 channel with Dolby surround) - cant remember if this is so. If it is there, it will still create 6 massive wavs as intermediary. Not sure how "intelligent" this downmix would be ie does it put the rear and center sounds correctly into a 2 channel file from the original 6

if's the original file is a 2 channel .ac3, this can be imported directly into Softencode, then bitrate reduced

[jdobbs]

As a suggestion, AZID does a very high quality job of downconverting from 5.1 Dolby Digital to 2 channel Dolby Surround if you want to go in that direction. Just as an interesting sidenote - AZID can also create a single 6 channel .WAV file (it can quickly get oversized though, as you can imagine).

If you want to stay 5.1 or just reencode a 2 channel source with a different bitrate jeffnoone is right -- its probably just as good or better to skip the 3rd party conversion and do it all directly with Softencode. But, as I recall (it has been a while though) Softcode's AC3 to PCM conversion was painfully slow..

Be warned when you choose lower bitrates. Standard quality AC3 encoding is 96Kbs per channel for stereo -- and the sound degrades pretty quickly when you drop below 64Kbs per channel.

jdobbs