If the hardware does not support it, then drivers and software won't fix it. I'm getting conflicting info as at least one site lists the gpu as being bitstreaming capable for HD audio.
Exactly, but, you then have to dive deeper. What does gpu not capable really mean. Is it truly the hardware, or, when someone says that, is it in fact the firmware. I am skeptical that the hardware could not.
In any event, the chances of it showing up on Plex in the next six months seems slim at best.
Which, sadly, strikes my consideration of Plex at this time. It's the most expensive HTPC/Streamer option I have been considering and I can't justify the $700 price tag of a new Mini when there will likely be no HD audio support now or in the coming months.
If that is your main criteria, then, totally agree with you. I hope you are able to find something to meet your needs in the near future. For me, not an issue since 99% of my use is playback of HD recordings off of Satellite, so, it’s irrelevant for me. Building up my collection of movies each and every day.
I think there are a lot of pieces to the puzzle, all of which have to be addressed before this will happen. I can’t imagine that happening that quickly!
Reading Apple’s own specifications, they state that the new Mac mini can send multi-channel uncompressed LPCM over it’s HDMI port to compatible receivers. There have also been some reports from people saying that they’ve been able to verify this. I’ve done some web searching myself, and I have also not been able to find a single report of anyone getting bitstreamed HD audio (DTS-MA / Dolby TrueHD) to output over HDMI.
Some Blu-rays have LPCM soundtracks, but it’s certainly not as common as DTS-MA and Dolby TrueHD. In theory then, Plex could decode all of the HD audio formats into PCM and send this over he HDMI link, although, as voip-ninja points out, there is not (as far as I’m aware) a free / open source decoder for DTS-MA available at this point.
The solution that I’m fairly happy to adopt, and shouldn’t be too difficult is as follows:
Most people that have HD movies on their HDDs have either downloaded them illegally, or have ripped them from original Blu-ray disks. In either case, it is likely that AnyDVD HD and EAC3To came into play to get the data off the disks and into a format for Plex to use (most likely an mkv container). EAC3To can easily convert (provided you have the right components installed) any HD audio format to either LPCM or FLAC. This can be done at the ripping stage, OR by re-processing the HD audio in an mkv container. Once you’ve done this, you should have a format that Plex could easily work with.
As it stands today, Plex (apparently, though I’ve never tried it) can decode FLAC on the fly to AC3. All the developers need to do is work out how to decode the FLAC signal to LPCM and send it over HDMI. If the LPCM data exists as is, that should be send directly.
It’s not quite as simple as bitstreaming the original HD Audio from the mkv / m2ts file, but it’s not that complicated, and should be not too difficult for Ryan to implement…
Any thoughts on this Ryan?
Neil.
Good summary Neil. Basically yeah. as soon as I get my hands on a HDMI mini, I'll be able to get LPCM output working. This will enable support for any encoded format ffmpeg supports.
The issue remains that there's minimal ffmpeg support for DTS-MA and Dolby TrueHD. Your suggestion of transcoding with eac3to is a reasonable workaround, as Plex will happily decode FLAC to PCM or encode to AC3 on the fly.
Once open-source decoders for those formats become available, we'll automatically benefit from ffmpeg's support.
-Ryan
I agree that Neil has provided a workable blueprint for this. The issue for me is transcoding my huge BD library is a giant pain in the ass. Although if subtitle support doesn't improve I will eventually be forced to do it anyway.
I'm the one that posted that on AVSForum. And the situation hasn't changed.
My question is: why is everyone here talking about "decoding"? I personally don't think that's the issue here... all we need is for the player/ffmpeg to bitstream the unmodified TrueHD or DTS-MA over HDMI. Shouldn't that be possible and much easier compared to a full blown decoder? Personally, that's all I would need since my receiver fully decodes these HD audio formats.
From http://support.apple.com/kb/HT4214:
Looks like 7.1 AAC is the way to go if you want sound quality > 5.1. When I'm able to invest in a new Mini I'll get this working in Plex.
Besides, let's be realistic. Most of the same arguments about AAC vs MP3 vs PCM vs 24bit/>48kHz audio apply here. The human ear can't actually perceive frequencies higher than ~22kHz. Nyquist theory dictates a 44.1kHz waveform has enough resolution to encode this frequency (basically double). AAC audio above ~128-160 kbps is transparent when compared to 16-bit 44.1kHz WAV (ie CD audio). In other words, the new HD audio formats are largely smoke and mirrors, and you're better off investing in better speakers.
-Ryan
why would you encode to a lossy 7.1 AAC? Plex handles muti-channel FLAC just fine
Because there's no real quality gain in using FLAC, and it takes up more space. If you prefer FLAC, as you say, go for it.
From Ryans post, I would say his thought is you can't HEAR the difference. There may be a technical difference as you say. The same rule applies to those video quality fanatics, compressing video does not always mean you can SEE the difference. If you do it wrong, of course you can see the difference. But uncompressed does not always = better.
well, if you have a good sound system it’s pretty easy to hear the difference, the sound difference between lossless and lossy audio encodes isn’t about high frequency retention (mp3 clips above about 18khz, but aac does fine with high freqs), it’s about detail and dynamic range. And yes even with my crappy ears, low-end receiver, and 25 year old speakers, I can generally hear a noticeable difference between between lossless music and high-bitrate lossy encodes. the people here wanting audio over hdmi probably dont care much about the extra 2 channels, not that many blurays actually have 7.1, they want hdmi audio so they can get lossless surround output.
A properly recorded 16 bit signal has ~ 100dB of dynamic range. This should be plenty for home theatre use.
This is tangential to my main point, that the hardware is incapable of HD bitstreaming. Once I get an HDMI Mini, i'll implement PCM output for those formats where an open-source or free decoder exists.
i was talking about the encode, not the output signal. and when you say people are better off investing in better speakers, the thing is that the folks that care about the lossless bluray audio already have the sort of high-end systems that it will make a difference for. but whatever, i dont want to drag this thread off on some unrelated pointless argument.
What about the hardware makes it technically incapable of bitstream passthrough? I’d think that that would be something that’s only software dependent.
Ask Apple or NVIDIA I guess. I think it has something to do with DRM, and the card needing to provide a protected audio path in the same fashion as HDCP. There's no Core Audio support for HD bitstreaming, and I don't think the Windows drivers support it either.
It turns out that only the GF104 chip (ie GTX 460) has the necessary Protected Audio Path to enable HD bitstreaming.
Is there anything I can try out on my new mac mini guys? I have various file formats.
I guess Apple is really making a point of not supporting BluRay in any way by selecting a video chip that cannot transport HD audio bitstreams out the HDMI port…
Hi guys
I just wanted to say that bitstreaming Dolby TrueHD, DTS HD-MA and LPCM over HDMI, with the new 2010 Mac Mini (Nvidia GT 230 GPU) works great in XBMC under Ubuntu (Linux).
It took a while to set up, but now that it’s done, it works just great and completely stable.
So the hardware definitely supports it 
Some info:
Ubuntu Lucid
Latest official Nvidia drivers
Latest ALSA driver
Editing some .conf files
Then it’s just a matter of choosing the “HDMI” output in XBMC and all the HD audio formats plays and sounds great.
Of course it would be much nicer (easier) if it all just worked out-of-the-box in Plex - I do miss OS X as my HTPC platform.
Although the main reason I left Plex (OS X) is the lack of “automatic refresh rate switching” based on content.
I really like that XBMC, under Ubuntu, switches automagically between 23.976 Hz, 24 Hz, 50 Hz and 60 Hz based on the video file I’m watching.
Regards
Martin
Great stuff! Now I need to install Ubuntu :) Thanks for posting your findings!
I too have left Plex on OSX due to lack of "automatic refresh rate switching".
Cheers
