DTS audio to S/PDIF with UPnP - working file!

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DTS audio to S/PDIF with UPnP - working file!

Postby wjo » Sun Feb 15, 2009 1:03 pm

Hi all,

As there have been lots of discussions about DTS audio in AVCHD files on disk (but not when streaming), I would like to see if this approach might be a potential way forward: I have a VOB file that plays perfectly fine on the PS3 through the PS3 media server with no transcoding. This particular file contains SD MPEG2 video and DTS audio that I can play back through my receiver connected with the optical S/PDIF cable. The trick to do this in this case is that both the PS3 media server and the PS3 sees a Linear PCM 2-ch 48kHz audio track, therefore passing it through completely unmodified. If the volume control setting in the PS3 GUI is touched obviously the sound (and the DTS indicator) goes out completely... The PS3 GUI shows Linear PCM as audio type, as expected, but the receiver knows it's DTS because of the way the audio data is formatted (works the same way as the DTS audio CDs that came out loads of years ago). This means that it's not really a proper DTS S/PDIF stream as the NON-Audio bit should be set in the flags, but there's no way we can get access to that without the PS3 actually recognizing the stream as DTS or AC3. I don't think setting the audio type to AC3 will solve it though as it will peak at 640kbps, not enough for DTS, LPCM seems to be the way to go for these receivers (mine's a Pioneer VSX-908RDS).

If anyone's interested here a link to the small file (~40MB): http://xnk.nu/dts/Logo-DTS.VOB I don't have enough time to pull it apart completely at the moment to see if there are any extra things to think about, but it seems that if the output stream to the PS3 can contain a Linear PCM soundtrack it should be possible to trick the S/PDIF connected receivers to play DTS. It probably won't work for HDMI connected receivers, but there the linear PCM transcoding would give good results anyway.

Back to the request part: It would be really nice (if this scheme works for HD video sources) to be able to choose not only the DTS to linear PCM transcoding but also have the possibility to remux the DTS stream into what looks like a linear 2-ch 48kHz stream (DTS data needs to be padded out to the full 1500kbps bandwidth allocated for the audio).

Can others play this example file back with full DTS? This would be an interesting experiment...

/wj
wjo
 
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby omel » Sun Feb 15, 2009 3:44 pm

wjo wrote:Hi all,

As there have been lots of discussions about DTS audio in AVCHD files on disk (but not when streaming), I would like to see if this approach might be a potential way forward: I have a VOB file that plays perfectly fine on the PS3 through the PS3 media server with no transcoding. This particular file contains SD MPEG2 video and DTS audio that I can play back through my receiver connected with the optical S/PDIF cable. The trick to do this in this case is that both the PS3 media server and the PS3 sees a Linear PCM 2-ch 48kHz audio track, therefore passing it through completely unmodified. If the volume control setting in the PS3 GUI is touched obviously the sound (and the DTS indicator) goes out completely... The PS3 GUI shows Linear PCM as audio type, as expected, but the receiver knows it's DTS because of the way the audio data is formatted (works the same way as the DTS audio CDs that came out loads of years ago). This means that it's not really a proper DTS S/PDIF stream as the NON-Audio bit should be set in the flags, but there's no way we can get access to that without the PS3 actually recognizing the stream as DTS or AC3. I don't think setting the audio type to AC3 will solve it though as it will peak at 640kbps, not enough for DTS, LPCM seems to be the way to go for these receivers (mine's a Pioneer VSX-908RDS).

If anyone's interested here a link to the small file (~40MB): http://xnk.nu/dts/Logo-DTS.VOB I don't have enough time to pull it apart completely at the moment to see if there are any extra things to think about, but it seems that if the output stream to the PS3 can contain a Linear PCM soundtrack it should be possible to trick the S/PDIF connected receivers to play DTS. It probably won't work for HDMI connected receivers, but there the linear PCM transcoding would give good results anyway.

Back to the request part: It would be really nice (if this scheme works for HD video sources) to be able to choose not only the DTS to linear PCM transcoding but also have the possibility to remux the DTS stream into what looks like a linear 2-ch 48kHz stream (DTS data needs to be padded out to the full 1500kbps bandwidth allocated for the audio).

Can others play this example file back with full DTS? This would be an interesting experiment...

/wj




Hi

I have a Pioneer VSX 909RDS and it plays fine here..


Omel
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby shagrath » Sun Feb 15, 2009 3:54 pm

this file contains a 2 channels LPCM track and NOT a dts one... optical cable is enough to play a stereo LPCM file but not a 5.1 one, unfortunately...
that's why it's working for you
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby wjo » Sun Feb 15, 2009 4:08 pm

shagrath wrote:this file contains a 2 channels LPCM track and NOT a dts one... optical cable is enough to play a stereo LPCM file but not a 5.1 one, unfortunately...
that's why it's working for you


Yes, that's the whole point, the container _thinks_ it's a LPCM track, but if you play it back through a DTS-capable receiver it is indeed a true DTS 5.1 track... If we can just package a remuxed DTS stream into something like this audio track we should be able to trick the PS3 into delivering it directly tp the receiver (which will play it as DTS). Does this make sense?

/wj
wjo
 
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Location: Sweden

Re: DTS audio to S/PDIF with UPnP - working file!

Postby wjo » Sun Feb 15, 2009 4:09 pm

omel wrote:Hi

I have a Pioneer VSX 909RDS and it plays fine here..


Omel


Good to know!! I sure hope that it's not only the Pioneer receivers that are capable of this though...

/wj
wjo
 
Posts: 8
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Location: Sweden

Re: DTS audio to S/PDIF with UPnP - working file!

Postby omel » Sun Feb 15, 2009 4:14 pm

wjo wrote:
shagrath wrote:this file contains a 2 channels LPCM track and NOT a dts one... optical cable is enough to play a stereo LPCM file but not a 5.1 one, unfortunately...
that's why it's working for you


Yes, that's the whole point, the container _thinks_ it's a LPCM track, but if you play it back through a DTS-capable receiver it is indeed a true DTS 5.1 track... If we can just package a remuxed DTS stream into something like this audio track we should be able to trick the PS3 into delivering it directly tp the receiver (which will play it as DTS). Does this make sense?

/wj


If this is true and working , there will be a lots of thinks there can be cheated on :D

I think he has'nt understood what you was trying to tell him



/omel
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby shagrath » Sun Feb 15, 2009 4:29 pm

WOW :)
you just solved the infamous DTS problem on ps3 !!!
no more LPCM conversion :)

you confirm you have really 5.1 on you receiver (I do not have a 5.1 one) ???
if this is confirmed I will work on this ASAP
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby wjo » Sun Feb 15, 2009 4:30 pm

shagrath wrote:WOW :))
you just solved the infamous DTS problem on ps3 !!!


Yes (maybe, hopefully)... I suspected that you misread my post the first time.. :)

And yes I can 100% confirm that all 5.1 channels are active, with the DTS indicator active...

/wj
wjo
 
Posts: 8
Joined: Sun Feb 15, 2009 12:41 pm
Location: Sweden

Re: DTS audio to S/PDIF with UPnP - working file!

Postby shagrath » Sun Feb 15, 2009 4:31 pm

wjo wrote:
shagrath wrote:WOW :))
you just solved the infamous DTS problem on ps3 !!!


Yes (maybe, hopefully)... I suspected that you misread my post the first time.. :)

/wj


no sorry I just run a ffmpeg against your file and just saw pcm data
but after extracting the track, it's indeed a dts track
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Re: DTS audio to S/PDIF with UPnP - working file!

Postby shagrath » Sun Feb 15, 2009 4:33 pm

ok, I will work on this tonight and release a new version asap if I got some results (great news, really)
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