Getting just PCM encoded to DD without affecting AC3/DTS passthrough, is it possible?

Slinkoff

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Hi

I have a fairly old but stable system running 7MC for all my media and I'm using S/PDIF pass-through to an amp that handles all my DD/DTS and for everything else I leave the amp on Dolby PLII to get pseudo-surround for live TV and bog standard AVI downloads. During the course of setting up my machine I found that AC3filter can encode PCM on the fly to DD and as I've never been happy with MP3s with PLII and I'm too lazy to cycle my amp through its 10 sound types to get to standard Stereo (there's no shortcut) I'd like to encode my MP3s to 2.1 or 5.1 on the fly. The main reason being that in AC3Filter I have finer control of the encoding including redirecting the low frequencies explicitly to my subwoofer and get a much richer sound than my amp's PLII gives me. Arguments about lossy to lossy and all that aside (I'm no audiophile), this is what I want to achieve.

So, I tried using AC3filter on its own and it mucked up the pass-through of DD/DTS in my MKV files, it started re-encoding the audio in those to 5.1 too rather than just passing it through and I couldn't see a way of tweaking the settings to avoid that. It seems that AC3Filter can't handle MP3s itself, it takes over once the MP3 stream has been decoded by whatever codec and comes into AC3Filter as PCM. There is an option under the "Use AC3 encoder" checkbox for "Do not encode stereo PCM" which is the exact opposite of what I want. I want "Only encode stereo PCM". Is there a way to achieve this?

One solution I thought of would be to use ffdshow for the AC3/DTS passthrough and use AC3Filter for PCM only but I'm not sure how or where to set the merits to achieve this combo. Something like this:

AC3/DTS - ffdshow
PCM - AC3Filter
MPEG2 - Media Foundation (or ffdshow/AC3Filter, don't think I care, if it's AC3Filter I guess I'd get 5.1 on Live/Recorded TV too?)

Could somebody give me some help on setting this up please?

Thanks

slink
 
well I managed to do it after trying lots of options and it wasn't actually that hard in the end. I now have MP3's and downloaded AVI's encoded with MP3 audio tracks upmixing to DD 5.1 with AC3/DTS in DVD's and MKV's passing through unaffected. I can post my settings if anyone else wants to get the same.

slink
 
Just post it anyway so that it can be found by search, should anyone be looking for it.

Incidentally this is what DDlive is for, converting multichannel PCM to DD on the fly, not sure about adding extra channels though. I think ffdshow can do this, IIRC someone here does that with their MP3s.

Also IMO, AC3filter is pretty unstable and unreliable.
 
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Incidentally this is what DDlive is for, converting multichannel PCM to DD on the fly, not sure about adding extra channels though. I think ffdshow can do this, IIRC someone here does that with their MP3s.
DD Live encodes everything though. So if you have stereo audio on your TV and stereo audio on your music if treats then both the same and you end up with the same issue as your amp is getting the same signal so uses the same settings (ie. you have both on Pro-Logic or both on stereo).

The key if to get music and TV to output differently. I have TV and films output stereo as DD 2.0 which the amp then turns into Pro-Logic and music as stereo PCM
http://www.avforums.com/forums/home-entertainment-pcs/991415-pro-logic-tv-stereo-music-last.html

Also IMO, AC3filter is pretty unstable and unreliable.
really? Other than the very latest version which I had a little bit of an issue with I have always found it really stable. (That is on XP though.....)
 
DD Live encodes everything though.

I know. I was just pointing out that's what it does. I didn't fully get what the OP was trying to do actually.

really? Other than the very latest version which I had a little bit of an issue with I have always found it really stable. (That is on XP though.....)

I've never got on with it at all. One minute it's working well for one type of track and then it screws up playback of another. Then for no reason, nothing plays as it should. I messed with it for years, ffdshow now is so much better it's in another league and left AC3filter redundant IMO.

Also, when AC3 converts 2 channel to DD on the fly doesn't it just add 3 empty channels rather than creating something in those channels, like the clever way that PLII does?

On the question about converting MP3 to 2.1, every AV amp that I've ever had does this with all 2 channel inputs as long as you set up the speakers to always split the low frequencies to the sub.
 
Also, when AC3 converts 2 channel to DD on the fly doesn't it just add 3 empty channels rather than creating something in those channels, like the clever way that PLII does?

Nope, it creates 5.1 and you have full control over how it does it, more so than on an amp doing PLII, at least on my amp. See the screenshot showing the input and output and note the levels. I also find AC3Filter to be rock-solid, never had probs with it.

On the question about converting MP3 to 2.1, every AV amp that I've ever had does this with all 2 channel inputs as long as you set up the speakers to always split the low frequencies to the sub.

Doing this on the amp affects everything, doing it at the HTPC end with AC3Filter again gives finer control over what audio gets manipulated and how.

Anyway, here's the settings I used to get my MP3's and AVI's upmixed to 5.1, It sounds way better than what PLII was doing as I could tweak around on AC3Filter's mixer tab until I got a nice rich bassey sound that's good to my ears (but would probably horrify any bat-eared audiophile). DTS/DD get passed-through untouched and Live and Recorded TV bypass AC3Filter so my amp still does PLII for those, which is how I want it. The AC3 for HD TV channels gets passed through untouched like any other AC3 audio.

I used Shark's codec pack as it was nice and easy. There is probably a way to get this working without having ffdshow in the chain but MP3s stopped working without it and it's there for video postproc and subs anyway so I left it in.









jameson_uk said:
The key if to get music and TV to output differently. I have TV and films output stereo as DD 2.0 which the amp then turns into Pro-Logic and music as stereo PCM
http://www.avforums.com/forums/home-entertainment-pcs/home-entertainment-pcs/home-...usic-last.html

Wish I'd seen your post before! You're doing similar stuff to me except I like tweaking the 5.1 in Ac3Filter, I prefer the overall sound for music and AVI films as I have the bass redirection on AV3Filter's Mixer tab set to 60 and the music sounds punchier for me while normal TV still getting the PLII treatment continues to sound natural. Personal preference though obviously.
 
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