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[bspachman]

This may be old news to some, but I've finally figured out how to get multi-channel DIGITAL output of AAC audio with MC!

The background:
I have lots of DVDs of TV series on my bookshelf. To simplify their management (and satisfy my TV jonesing), I've slowly been ripping the DVDs, transcoding the individual episodes, and using MC to play back the resulting compressed episodes.

I use Nero Recode for the transcoding duties. At the end of a transcoding session, I have an MP4 container that holds H.264 Video (known as AVC) and AAC audio (known as AAC-LC). The audio is generally multi-channel 5.1 surround sound.

Because I connect my MC playback machine to an A/V receiver via an optical SPDIF connection, I've been resigned to having the receiver interpret the signal as 2-channel....

Imagine my surprise today when I discovered that the version of ffdshow included in the CCCP pack can output AC3-encoded audio ON THE FLY from whatever input it's getting. You can even specify that only multi-channel audio gets that treatment! It's all there in the 'Output' settings of ffdshow.

(obMediaCenterBug)
Altering these settings in ffdshow while playback is occurring crashes MC....

So I am a happy camper! My multi-channel MP4 files are now playing back in MC, with ffdshow doing the heavy lifting of decoding the H.264 video as well as decoding the 5.1 Channels of AAC-LC audio and transcoding those channels on the fly to 5.1 channels of Dolby digital over SPDIF.

Yay!
brad

[fitbrit]

Thanks for the tip.

[BartMan01]

Good tip for getting AAC 5.1 to a non AAC receiver, but...  why not just rip/encode to a format/container that supports AC3?  What it sounds like you are doing is transcoding AC3 to AAC then back to AC3 again for playback.  You could put them all in Blu-Ray compliant M2TS format using H.264 for the video and keeping the original AC3 audio. 

My guess is that given the subject matter (TV shows usually don't have demanding/critical audio), the loss in audio quality from a dual transcode is negligible/unimportant to you compared to ease with using Nero to process the files.  I use Nero the same way for taking content on the road when I am out of town.

Edit:  FYI  - one of the options in Nero Recode audio for me is AC3 (Copy from Source).  I am running the latest version with the HD plugins - so I may have some extra options.

[bspachman]

Points well made...

I may well have chosen a different container format (eg. mkv) if:

1) I had known about them when I began the project. Ignorance is not always bliss
2) If the loss in audio quality due to dropping the bitrate from 640k for AC3 to 128 or 160 AAC wasn't a more overwhelming change.
3) But most importantly, I have a lot of different devices that I use to play back these files. Many of those devices are made by Apple, and I wasn't interested in doing the amount of hacking required to get iPods, Apple TVs, etc. to playback mkv files.
4) I haven't upgraded to Nero8, so I don't think I have the passthrough option you've got.

But I'll keep my eye open on the m2ts container....I may yet switch, but as you said, TV isn't terribly demanding on the audio side of things. A show like "The Muppet Show" or even "The West Wing" just requires a good stereo encoding...

brad

[BartMan01]

MKV is 'interesting' but pretty much unsupported in consumer devices.  It is probably the best and most flexible container out there - but media corporations are afraid of open source so I would be surprised if it ever went beyond a niche format.

The fact that you are wanting to easily get the content to Apple devices would pretty much limit you to MP4 with H.264/AAC.  Apple fanboys would say that 'this is best' - totally ignoring the fact that most content is already AC3 (so the resulting AAC can be no better and will probably be worse from transcoding) and that AAC support in receivers/preamps is still limited.  The good news is that AAC support seems to be a common feature of the 2008/2009 receiver lineup.

[fitbrit]

MKV is 'interesting' but pretty much unsupported in consumer devices.  It is probably the best and most flexible container out there - but media corporations are afraid of open source so I would be surprised if it ever went beyond a niche format.

Actually 2008 is the year where consumer companies start/ have started bringing out mkv compatible devices. SageTV already has its HD Media Extender. I'd love for JRiver to bring out the same device in MC compatible format. There's also the Popcorn Hour unit, a couple by TVIX too. Finally, a big Chinese player's Canadian rep has been in touch with me for my opinions on mkv support. As a result of his own research and our conversations, he will probably be pushing to get an mkv player (with or without a DVD player) released in North America. It appears that the Asian market is more interested in RMVB support, however.