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AC3 passthrough problem - Printable Version

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--- Thread: AC3 passthrough problem (/showthread.php?tid=298877)

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AC3 passthrough problem - markoweb - 2016-12-04

Hi,
I have problem with playing AC3 on my ARV.

My configuration is following:
Rapsberry PI 2
AVR: JVC TH-S3
TV: 32LG3000

Tried connections:
1) RPi2 --(HDMI)--> TV --(S/PDIF)--> AVR
2) RPi2 --(USB)--> (external sound card) --(S/PDIF)--> AVR

Kodi audio config:
Passthrough on
AC3 enabled
transcoding enabled
EAC3 disabled
DTS enabled

Symptoms:
playing DTS (DTS-MA) sound (movie) works - AVR shows DTS input sign
playing AAC movie doesn't work - AVR shows LPCM and plays coded sound
after manually changing the source data type on AVR to DoblyDigital, sign is only blinking and plays nothing

I have tried kodi 16. and 17. also

LOG: https://paste.ubuntu.com/23577700/

Thanks for help


RE: AC3 passthrough problem - fritsch - 2016-12-04

AAC is not(!) AC3.

In order to transcode it to AC3, enable 2.0 channels and enable Dolby Transcoding.


RE: AC3 passthrough problem - markoweb - 2016-12-04

Hi,
thanks,

I have set it:
Number of channel: 2.0
Enable Dolby Digital (AC3) transcoding: on

(otherwise it's sending the Linear PCM)

log

Are there some transcoding options?


RE: AC3 passthrough problem - DJ_Izumi - 2016-12-05

Doesn't Kodi only transcode if the source is more than 2.0 channels and send LPCM if it is 2.0 or less? (I mean, why wouldn't it? 2.0 AAC decoded to LPCM is a lossless conversion, where as 2.0 AAC transcoded to 2.0 Dolby Digital is a lossy conversion)


RE: AC3 passthrough problem - markoweb - 2016-12-05

Hi,
actually yes, but S/PDIF can handle only 2 channels, then I have to use the lossy conversion.


RE: AC3 passthrough problem - fritsch - 2016-12-05

If the input is 2.0 channels - then there is no reason to transcode.

My suggest 2.0 setting was for the PCM Output settings. Cause AC3 works via 2 pcm channels only. Transcoding 5.1 AAC to 5.1 AC3 and then outputting that virtual format via 2 channels is the workaround to hear surround also via SPDIF.


RE: AC3 passthrough problem - fritsch - 2016-12-05

(2016-12-04, 22:41)markoweb Wrote: Hi,
thanks,

I have set it:
Number of channel: 2.0
Enable Dolby Digital (AC3) transcoding: on

(otherwise it's sending the Linear PCM)

log

Are there some transcoding options?

So then .. what you wanted. AC3 = AC3, DTS = DTS and TrueHD -> AC3, DTS-HD -> DTS and Every other multi channel PCM track -> AC3.


RE: AC3 passthrough problem - markoweb - 2016-12-05

Yes, that's what I expected.
But I get nothing from my AVR.

If is AVR set to auto source mode it selects LPCM and plays (dial-up modem kind) coded sound
When I set it to DolbyDigital then it plays nothing

(this happens only when the AC3 transcoding is set to on)


RE: AC3 passthrough problem - fritsch - 2016-12-05

Most likely your AVR also does not cope with 640 Kbps AC3. Too bad. Can you verify that, e.g. check normal 640 kbps AC3 -> should not work and then try 448 kbps AC3 and 384 kbps AC3 -> should work?

Try: http://fritsch.fruehberger.net/samples/result-384.ac3 (Transcoding disabled but AC3 enabled)
Try: http://fritsch.fruehberger.net/samples/result-640.ac3 (Transcoding disabled, but AC3 enabled)


RE: AC3 passthrough problem - markoweb - 2016-12-05

Hi, thanks!
I'll try it, but I'm quite sure that that is the case.
What would be my options than?


RE: AC3 passthrough problem - fritsch - 2016-12-05

None - cause a gui setting for changing the default transcoding bitrate was vetoed. As you most likely use LibreELEC / Millhouse builds, link him to this thread. The patch is trivial and a one liner. But try those things first, please.


RE: AC3 passthrough problem - popcornmix - 2016-12-05

@fritsch does this look right?

@markoweb tonight's Milhouse should support the option in advancedsettings.xml:

Code:
<advancedsettings>
  <audio>
    <ac3bitrate>384000</ac3bitrate>
  </audio>
</advancedsettings>

which may or may not help.


RE: AC3 passthrough problem - da-anda - 2016-12-05

there is a bug in your commit, commented on github


RE: AC3 passthrough problem - popcornmix - 2016-12-05

(2016-12-05, 15:35)da-anda Wrote: there is a bug in your commit, commented on github

Thanks. I've pushed a fix.


RE: AC3 passthrough problem - markoweb - 2016-12-05

Hi,
I tried those files but non of them works,
can you provide some with even less bitrate

Thanks


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