multichannel wav/ flac -> no passthrough possible?!
#16
(2014-05-19, 06:57)606u Wrote:
(2014-05-17, 06:44)nickr Wrote: wav is not DTS! nor is flac!
I believe what thread's starter asks is about this:

You can record an audio-CD with RAW 1,411.2 kbit/s DTS instead of RAW 1,411.2 kbit/s PCM, and, if signal is transferred 1:1, in digital, your receiver will (most likely) pickup DTS stream and will decode it; hence, you get 5.1 audio from a "standard" CD-audio. You can also treat RAW DTS data as RAW PCM (even if it is not) and apply FLAC compression.
Embedding a DTS stream within a WAV file is a clever hack, but a hack nevertheless, not guaranteed to work - only if the entire playback chain passes it through bit perfect will the receiver see a DTS stream. Otherwise you just have white noise.

The player (omxplayer / paplayer etc) and the new audio engine in Gotham would have to pass the data through unaltered. Any change at all and it will fail. For example, because XBMC thinks it is sending a raw PCM stream if you adjust the volume within XBMC (+/- buttons) to anything other than 100% the data is no longer bit perfect.

If you use the Volume amplification setting (within the Audio OSD controls) the data is no longer bit perfect. If sample rate conversion is enabled in the new audio engine settings it is no longer bit perfect, etc...

You could try this, but it still may not work:

* Make sure volume is set to 100% in XBMC.

* Make sure volume amplification is set to zero.

* In system settings enable expert settings and go into the audio output section and try different settings for "Output configuration", the default is optimized, you might find "Fixed" and a sampling rate of 44.1Khz works to prevent resampling which would otherwise prevent a bit perfect transfer of PCM data.

Good luck, but don't expect it to work.

The only way it could ever be reliable is if the player itself had support added to detect a DTS/AC3 stream within a PCM container and switch into a "PCM passthrough" mode where it sends the data to the receiver as unaltered bit perfect PCM. (Disabling resampling, volume adjustment etc)
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#17
Followed your advices. Unfortunatelly without success, no DTS stream.

Quote:The only way it could ever be reliable is if the player itself had support added to detect a DTS/AC3 stream within a PCM container
XBMC already detects the DTS stream in the wav file (according to the player screen), but is not able to passthorugh, like it does in movies. Huh

Okay, I think I have to quit and accept it for now. I have tried every kind of setup, no idea left. From my point of view passthrough should be possible (because it is working for movies perfectly), but I can´t change. Maybe one day somebody else will come up with that topic again.

Many thanks to all of you for your support.
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#18
I've got several DTS multi-channel audio files (ripped from DVD-A discs) that are encoded with WAV headers then stored as FLAC files and these play wonderfully on my Squeezebox2 (optical out) - there's a Wiki page describing the process although DBMandrake is 100% correct, if the volume on the Squeezebox is adjusted away from 100% the output bitstream is no longer perfect and all you get is white noise (or silence, depending on how the amp responds to garbage audio input).

These tracks DO play correctly with both paplayer and dvdplayer on OpenELEC 4.0.2 on x86 (Revo 3700) over HDMI to my Onkyo TX-NR828 amp with XBMC set to pass-through DTS etc. It hasn't always been this way, it certainly never worked with Frodo, so I suspect this is a Gotham feature.

Unfortunately my R-Pi (with a recent OpenELEC Helix build) isn't hooked up to my amp and I'm only getting white noise from the Pi (tested paplayer, dvdplayer and omxplayer) when connected to the stereo speakers of my monitor.

I've uploaded a small sample audio file (6MB on Dropbox) here that you can test - you should hear matches being struck from each speaker in turn (Front Left -> Front Right -> Rear Left -> Rear Right -> Centre).

My x86 audio settings:
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#19
(2014-05-21, 09:33)MilhouseVH Wrote: Unfortunately my R-Pi (with a recent OpenELEC Helix build) isn't hooked up to my amp and I'm only getting white noise from the Pi (tested paplayer, dvdplayer and omxplayer) when connected to the stereo speakers of my monitor.
That would be expected - if you're outputting analogue audio you'd only get noise, and if you're sending HDMI audio to the monitor but it doesn't support DTS decoding it can only decode it as PCM and also give noise. (or silence)

Unless the player could be modified to heuristically check for the presence of DTS encoding with a PCM stream and switch modes so that it passes it through bit perfect (to a DTS capable receiver) or decodes it in software. Should be possible in theory, but might be a lot of work for what is still a hack.
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#20
I've just lugged my Pi (latest Helix build - I think I've now got a hernia) over to my amp and using the same passthrough audio settings as x86 the above sample file plays perfectly fine with paplayer, but gives white noise with dvdplayer and omxplayer.
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#21
I did the test with the above sample file. Plays perfectly 5 channels with the 3 players.
OE displays Flac and AVR displays DTS.

Could you tell me why when I play the files from DIATONIS (see my previous post)
Flac file: OE displays Flac and AVR displays PCM
DTS(,wav) file: OE displays DTS and AVR displays PCM

BTW when playing Flac, CPU usage (in OE Summary info) is mini 75%, med ~85%, max 100%
when playing DTS(.wav) CPU usage is min 53%, med ~64, max 76%
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#22
Strange, I could only get it to play correctly with paplayer but I didn't spend long trying with dvdplayer and omxplayer.

Don't know about the DIATONIS samples, my guess would be the encoding isn't quite what XBMC expects (or maybe it's because they're 44.1KHz/96Khz and my sample is 48Khz?), I'll see if they play on my Squeezebox.

Don't trust the Summary Info page - it will use a heap of CPU just to update the GUI with the now inflated CPU information. Only use top, or bcmstat.sh, to monitor CPU load of the Pi - its impossible to monitor CPU load accurately from within XBMC itself.
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#23
Of the DIATONIS samples, I tried playing "In Fields of Green I Met Her" (FLAC5.1, 96 kHz/24-bit/5.0) on x86 XBMC with paplayer and it played fine - all 6-channel of PCM output to the amp.

This file won't play on my Squeezebox, I suspect 96kHz is too much for the poor thing. This doesn't look like it's a DTS file though, so the fact PCM is being output would be correct as that's with it most probably is, WAV not DTS.

I'm not sure any of those FLAC files on DIATONIS are actually DTS encoded as WAV? It doesn't say any of them are DTS.

I tested one of the files described as "DTS 5.1 Surround Files", the first one called "The Secret Universe", and this played correctly on x86 XBMC, outputting DTS to my amp. It doesn't however play at all on the Squeezebox...

So it looks to me that x86 - and possibly Pi - XBMC 13.1 (OpenELEC 4.0.2) is able to correctly passthrough WAV encoded DTS and also multichannel PCM from FLAC and WAV "containers" (not entirely sure of the terminology here, but hopefully you all understand).
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#24
Quote:This file won't play on my Squeezebox, I suspect 96kHz is too much for the poor thing. This doesn't look like it's a DTS file though, so the fact PCM is being output would be correct as that's with it most probably is, WAV not DTS.
However, Mediainfo says:
FLAC Free Lossless Audio Codec
4mn 55s Variable 4 312 Kbps
6 channels Front: L C R, Back: L R, LFE
96.0 KHz 24 bits
152 MiB (99%)
libFLAC 1.2.1 (UTC 2007-09-17)
and
DTS Digital Theater Systems
14 Little 1
4mn 55s
Constant 1 411.2 Kbps
6 channels Front: L C R, Side: L R
44.1 KHz 24 bits
Lossy
49.7 MiB (100%)

Quote:So it looks to me that x86 - and possibly Pi - XBMC 13.1 (OpenELEC 4.0.2) is able to correctly passthrough WAV encoded DTS and also multichannel PCM from FLAC and WAV "containers" (not entirely sure of the terminology here, but hopefully you all understand).
I don't agree/understand: If OE is able to passthrough WAV encoded DTS, my AVR should decode DTS and display DST (not PCM as it does)
Config, video/audio player:
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                                          <nfs wired> Linksys WRT32X router <USB> 4T HDD
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#25
Have you tried muxing your music into a sane container like mka? the wav container was never designed for flac or dts.

I don't even know what "wav encoded dts" means. You seem to be confusing codecs with containers.
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#26
Quote:I've uploaded a small sample audio file (6MB on Dropbox) here that you can test - you should hear matches being struck from each speaker in turn (Front Left -> Front Right -> Rear Left -> Rear Right -> Centre).

With my Pi (openelec4.0.2) just white noise...
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#27
(2014-05-22, 09:35)MrNice Wrote: However, Mediainfo says:
FLAC Free Lossless Audio Codec
4mn 55s Variable 4 312 Kbps
6 channels Front: L C R, Back: L R, LFE
96.0 KHz 24 bits
152 MiB (99%)
libFLAC 1.2.1 (UTC 2007-09-17)
and
DTS Digital Theater Systems
14 Little 1
4mn 55s
Constant 1 411.2 Kbps
6 channels Front: L C R, Side: L R
44.1 KHz 24 bits
Lossy
49.7 MiB (100%)

OK, you're talking about two different versions of the same file:

The first chunk of mediainfo output corresponds to the "FLAC 5.1 Surround Files" -> "In Fields of Green I Met Her" (BWCTYT) (96 kHz/24-bit/5.0) which doesn't have any DTS component, it's only PCM so when this is played by XBMC I get multi-channel PCM output and displayed by the amp, which is totally correct.

The second chunk is the "DTS 5.1 Surround Files" version of the same file which is DTS stored as a WAV. When I play this file on x86 OE, I get DTS shown on my amp, and output by my amp. Again, this is correct.

(2014-05-22, 09:35)MrNice Wrote: I don't agree/understand: If OE is able to passthrough WAV encoded DTS, my AVR should decode DTS and display DST (not PCM as it does)

My guess is that XBMC plays the WAV file as a plain WAV, passing the bit-perfect bitstream through to the amp and doesn't actually know it's playing a DTS file. However the amp "sees" (or should see) DTS audio data and decode it as DTS (in my case, anyway).

If your amp is outputting/displaying PCM here instead of DTS, then I can't explain that as my amp shows DTS. Are you actually hearing the correct DTS audio, or white noise? Could it just be an amp display issue? Encapsulating DTS as WAV is a bit of a hack after all.

Edit: I just re-tested the Pi (Helix) with the DTS WAV files and they also now appear as PCM on my amp (play fine though), so there /is/ a difference between Pi (paplayer, Helix build) and x86 (paplayer, Gotham build). It seems only minor though, as the audio sounded the same.

An AC3 (Dolby Digital) WAV file appears and plays as Dolby Digital though on both Pi and x86.

(2014-05-22, 10:51)Bluebuster83 Wrote:
Quote:I've uploaded a small sample audio file (6MB on Dropbox) here that you can test - you should hear matches being struck from each speaker in turn (Front Left -> Front Right -> Rear Left -> Rear Right -> Centre).

With my Pi (openelec4.0.2) just white noise...

Using paplayer? And you had DTS passthrough enabled (refer to my audio settings in post #18)?

I am using a Helix build on Pi however, but would be a little surprised if that is the reason as official x86 4.0.2 OE plays without a problem.
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#28
(2014-05-22, 10:43)nickr Wrote: Have you tried muxing your music into a sane container like mka? the wav container was never designed for flac or dts.

I don't even know what "wav encoded dts" means. You seem to be confusing codecs with containers.

In the case of the Squeezebox it's adding a WAV header to DTS data so that it is played as a WAV. Have a look at the wiki page I linked to previously:
Quote:spdifconvert.py is a Python script which takes as input an AC3 or DTS file (sourced from a DVD) and encapsulates it in an IEC61937 stream. This stream is then wrapped in a WAV file which can be played over an S/PDIF link with no modifications (ie no volume adjustments); a digital receiver will be able to interpret the AC3 or DTS data contained within this stream (assuming the receiver knows the AC3/DTS formats).
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#29
Quote:Using paplayer?
Yes. tried all 3 players, all of them white noise.

Quote:And you had DTS passthrough enabled (refer to my audio settings in post #18)?
Yes Sir.

Quote:My guess is that XBMC plays the WAV file as a plain WAV, passing the bit-perfect bitstream through to the amp and doesn't actually know it's playing a DTS file. However the amp "sees" (or should see) DTS audio data and decode it as DTS (in my case, anyway).
Actually, XBMC KNOWS playing a DTS file, because it is shown correctly in the fullscreen display of XBMC as "DTS 5.1".
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#30
(2014-05-22, 10:43)nickr Wrote: Have you tried muxing your music into a sane container like mka? the wav container was never designed for flac or dts.

I don't even know what "wav encoded dts" means. You seem to be confusing codecs with containers.

http://tehparadox.com/forum/f85/what-dts...how-63792/

Quote:What is DTS Audio CD?

The DTS-CD, DTS Audio CD or 5.1 Music Disc (official name) is an audio Compact Disc that contains music in surround sound format. It is a predecessor of DVD Audio. Physically, it conforms to the Red Book standard, except for the way the music is encoded on the CD. Where regular CDs store the music as linear PCM, the DTS-CD stores music using the DTS format, with the same fixed bitrate as 16-bit linear PCM, namely 1,411,200 bits/s or roughly 1,378 Kib/s.

As opposed to other surround formats, such as Super Audio CD and DVD-Audio, which require a specialized player, a DTS-CD is compatible with most standard CD players with a digital (S/PDIF) output. CD (and DVD) players recognize the disk as a standard audio CD. The only requirement is a receiver that can decode DTS audio.
A normal CD player will output what it thinks is a PCM stream over a SPDIF connection to a recevier, but the receiver will recognise the signature of a DTS stream and decode accordingly.

If that CD is ripped to a wav file the conversion is lossless so if that wav file is then played out losslessly over SPDIF (or HDMI) as 2 channel PCM the receiver will again recognise the DTS encoding and decode it accordingly.

If even a single bit is changed in the stream between the wav file and the digital stream being sent to the receiver the data will be corrupted. Because the player thinks it is only PCM data it believes that it is ok to change the data in certain ways - for example scaling the values to adjust the volume but this will corrupt the DTS data, as will resampling to a different sample rate.
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