LPCM wrapping expert help

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LPCM wrapping expert help

Postby mario595 » Tue Dec 11, 2012 5:08 am

I am running 1.60.0 with "Keep AC3 track" and "Keep DTS track" selected.

My PS3 is hooked up to TV via HDMI (speakers off on TV) and optical to amp which natively recognizes AC3, DTS, LPCM multichannel 44-96hz. I can watch MKVs with a DTS track by simply having these options enabled which fool the PS3 into sending the track directly to the amp in an LPCM header. The DTS light will be on the amp when playing such a file.

I recently purchased a couple cheap 32" HDTVs wich will eventually be connected to the PS3 via a matrix splitter. When I do so I will be sending the audio via HDMI to these TVs. The TV audio is just static when I play a file with a DTS track. The TV tries to play a compressed DTS signal as uncompressed LPCM. No mystery there.

The TVs will be in other rooms. I am running a test to see if I can stream the DTS signal to a local amp or sound bar via the 32" TV's digital output. The TV's settings for the audio digital output are OFF,PCM,RAW. The mock-up test involves one of the 32" TVs, my PS3 slim firmware version 4.25, an Onkyo amp with one or its SPDIF digital inputs connected to the digital audio output of the TV. No Matrix splitter or long HDMI cables involved for this test.

I set the PS3 slim to output audio via HDMI only. While the slim / 4.25 allows you to select BITSTREAM or LPCM for BD/DVD audio output format; for other audio output there is no "Bitsream" option. You have to pick which formats are supported by the device being connected to the HDMI cable. I get different test results with those settings as follows:

Code: Select all
Test 1
File playing:              .m2ts with x264 video and AC3 audio
PS3 HDMI output setting:   Linear PCM 2ch 44khz + Linear PCM 2ch 48khz 
TV digital output setting: RAW or PCM
Amp input format display:  PCM
Amp output format display: Neo 6 (2 channel)

Test 2
File playing:              .m2ts with x264 video and AC3 audio
PS3 HDMI output setting:   Linear PCM 2ch 44khz + Linear PCM 2ch 48khz + DD 5.1 + DTS 5.1
TV digital output setting: PCM
Amp input format display:  PCM
Amp output format display: Neo 6 (2 channel)

Test 3
File playing:              .m2ts with x264 video and AC3 audio
PS3 HDMI output setting:   Linear PCM 2ch 44khz + Linear PCM 2ch 48khz + DD 5.1 + DTS 5.1
TV digital output setting: RAW
Amp input format display:  PCM
Amp output format display: DD (actually the symbol for dolby digital)
Amp format display shows:  DolbyD (6 channel)

Test 4
File playing:              .mkv with x264 video and DTS audio
PS3 HDMI output setting:   Linear PCM 2ch 44khz + Linear PCM 2ch 48khz + DD 5.1 + DTS 5.1
TV digital output setting: RAW or PCM
Amp output:                static


I selected the media server setting "Use LPCM for audio" just for the heck of it but no difference.

I expected Test 4 to work like Test 3 (except the amp would show DTS) but that is not the case. I also don't understand why Test 1 didn't pass an AC3 track to the amp when the TVs digital audio output was set to "RAW". The HDMI output setting is having an affect here. Again there is no "bitstream" option for HDMI on media other than disc.

I read a bunch of threads but can't figure out exactly what is going on here. Can anybody explain these test results?

BTW, there is no longer an audio option for Left+Right from the control option when playing a video.
mario595
 
Posts: 62
Joined: Mon Nov 09, 2009 7:12 pm

Re: LPCM wrapping expert help

Postby mario595 » Tue Dec 11, 2012 6:17 am

Some more info about TEST 2,3,4...

I also selected all the Liner PCM 5.1 channel options in the PS3 menu.

Some more info on this 32" TV...

The TV doesn't say specifically that it can decode a Dolby Digital or DTS signals for the TV speakers. If I force my DVR to output dolby digital over HDMI; there is no sound from the TV speakers. As per the DVR manual that is expected if the TV can't decode Dolby Digital:

"If you connect your DVR to an HDTV that cannot support Dolby Digital audio, the HDMI interface instructs the DVR to switch its audio outputs to 2-channel PCM audio (to be compatible with the HDTV)."

The TV propaganda states:

Digital Theater-Quality Audio
Surround your TV with digital audio. If you have a surround sound receiver or other compatible device, you'll be able to get pure digital sound from your TV. Experience 5.1 channels of audio bliss in the comfort of your living room.

So it can recognize 6 discrete channels but maybe only as LPCM ??? Test 3 did prove that the DD was passed through to the receiver when the TV output was set to "RAW". When TV output set to "PCM" only 2 channels were passed to receiver. I don't remember what the TV speakers were doing during all these tests as I turned them down to not blow them up when testing DTS. But I could swear they worked in RAW and PCM with an AC3 - not 100% on that.

EIther way, doesn't explain to me why the DTS is not getting passed.
mario595
 
Posts: 62
Joined: Mon Nov 09, 2009 7:12 pm


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