[LINUX/MAC/WINDOWS] AAC/FLAC/WMV 5.1 pass-through to SP/DIF out: transcode to AC3 5.1

I have a file taken from a bluray source called xyz.1080p.5.1.wmv which I am trying to get to work on my mac mini using XBMC. I have the audio set to digital and XBMC recognises that its 5.1 in the stream option. However I get no sound output. My Mac Mini is plugged into a surround amp using an optical cable. The configuration works Ok for other files with surround sound which the processor sees as DTS.

Any ideas?

TIA

Update:
VLC wont run the file, I managed to run using QT with Flip4Mac

Not supported yet by XBMC code, see these related suggestions for more information:
http://forum.xbmc.org/showthread.php?tid=39663
http://forum.xbmc.org/showthread.php?tid=34130
http://forum.xbmc.org/showthread.php?tid=36982
feature requests:
http://trac.xbmc.org/ticket/4450
http://trac.xbmc.org/ticket/4871
http://trac.xbmc.org/ticket/5188
and patch with one possible solution:
http://trac.xbmc.org/ticket/4859

Dam0 Wrote:Slippy,

i ended up using mkvextract to demux, then loaded the *.AAC into nero soundtrax and exported it as ac3. then remux using mkvmerge, and now i have working mkv with ac3.
regards,
Dam0

What version of SoundTrax are you using? I have the latest, and it doesn't have an option to export to AC3.

CrashMonkey Wrote:What version of SoundTrax are you using? I have the latest, and it doesn't have an option to export to AC3.

ive recently upgraded to nero vers 9 i think, so i currently have soundtrax vers 4.0.18.0, but i cant rem if i performed the process described prior to upgrading nero.

im sorry i cant be more specific, as i have deleted all my aac files since converting them.

regards,
Dam0

when you go to export, the ac3 option isn't there. checking the version that comes with nero 8 now...

Just confirmed, the option IS there withe Nero 8 version, 3.3.4.

Thanks.

not really sure what the hell nero is up to these days, they've removed or broken a ton of stuff with this new release.

Hi there,

I've been a long time user of XBMC on the original Xbox platform (best app ever written for that machine!). I'm currently running Plex 0.7.5 on my Mac Mini, and XBMC 8.10 on my Apple TV.

It's getting harder to find replacement parts for the old Xbox, so I'm looking for the next media center platform. I'd like it to be a modded Apple TV but my testing so far is less than perfect.

I have quite a few multi-channel FLAC albums I enjoy and would need support for it on AppleTV. As well as .DTS files and DTS encapsulated .WAV files.

Here are the results of multi-channel testing:
- Format: FLAC, 6 channels, 24bit samples, 48kHz (sample FLAC)
+ Platform:XBMC on AppleTV
+ Result:Time index does not advance, no sound (reciever gets nothing)
- Format: FLAC, 6 channels, 24bit samples, 48kHz (sample FLAC)
+ Platform:plex on MacMini
+ Result:Time index advances slowly, no sound (reciever gets nothing)

- Format: FLAC, 6 channels, 24bit samples, 96kHz
+ Platform:XBMC on AppleTV
+ Result:Time index does not advance, no sound (reciever gets nothing)
- Format: FLAC, 6 channels, 24bit samples, 96kHz
+ Platform:plex on MacMini
+ Result:Time index advances very slowly, no sound (reciever gets nothing)

- Format: .DTS
+ Platform:XBMC on AppleTV
+ Result:Plays great (reciever gets DTS stream)
- Format: .DTS
+ Platform:plex on MacMini
+ Result:Plays great (reciever gets DTS stream)

- Format: DTS encapsulated in .WAV file
+ Platform:XBMC on AppleTV
+ Result:2 channels of static
- Format: FLAC, 24bit, 48kHz
+ Platform:plex on MacMini
+ Result:2 channels of static

In short, I think the Mac OS X / Apple TV ports of XBMC/Plex are no longer doing on-the-fly Dolby Digital AC3 transcoding of multi-channel PCM streams to create the 5.1 sound.

This feature is missing from the Mac OS X / Apple TV versions, can it be brought to it please? I know it's not ideal, but it gets us by. It was a well used feature of the Xbox platform XBMC.

Thanks

A patch would be welcome. There's noone currently working on it.

schmoko Wrote:IGNORE PREVIOUS POST

Issue appears to be here:

ALSADirectSound.cpp:

// TODO - add an option to only downmix if user want's us
if(iChannels == 6)
deviceuse = "xbmc_51to2:'" + EscapeDevice(deviceuse) + "'";

Seems as if a52encode requires that the number of channels IN matches the number it is configured with in asound.conf. If the source has 6 channels, XBMC automatically converts them to 2 channels. Since a52encode expects 6 channels, and only gets 2, it cries. This is the bug.

A quick fix (for me) was getting keeping the source input in 6 channels when we are using a52encode. However, this only fixes the issue when the source already matches the number of channels a52encode is expecting. If the source is stereo, or the source is 7 channels, this fix wont work.

The REAL solution would be to add code so that if device is a52encode, XBMC converts all sound to the expected number of channels (from asound.conf) and then passes it through. My code-fu isn't quite up to the task, but this may be a worthwhile task at some point.

I would say it isn't high priority though... Fixing the issue raised a secondary issue. It turns out a52encode is very slow, and playing 1080p content and encoding 6 PCM channels in real-time was far more then my puny 5600+ could handle. Until we have a hardware solution for a52encode (like DTS Connect! and Dolby Live!) or we can unload decoding to the GPU and free up CPU, this doesn't seem like a good solution.

I may be talking to myself, but I wanted to make sure this was all noted in the event someone runs into any of these issues in the future.

What source code changes did you make to do this?

Gamester17 Wrote:and patch with one possible solution:
http://trac.xbmc.org/ticket/4859

How can test this patch ?

Sorry for the dumb (?) question but if is not so much trouble, can someone guide me with this ?


Thanks