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[PROBLEM] No Dolby Digital (AC3) audio? - Printable Version

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No Dolby Digital (AC3) audio? - andoni - 11th Dec, 2013 01:01 PM

Hi there,

I have a RPi type B running the latest xbian (beta2). My setup is as follows:
RPi HDMI--> TV (Westinghouse DWM40F) Coax--> Receiver (Kenwood VR-3090)

Everything seems to work fine except when I play any video with AC3 audio (I don't have movies to test DTS, but I suspect that it will not work either.)
Xbmc seems to be bitstreaming the audio fine since my amplifier recognizes the format as AC3 and displays 'Dolby Digital' on its screen, but either no sound comes out or couple of seconds of grumble.
I read in some posts that xbmc does not include flagging bits that are compatible with old amps for AC3 handshaking. Is there a way to add those? This has been very frustrating to figure out.
Thanks.

xbmc gui settings:
Audio out: HDMI
Speaker Config.: 5.1
Ac3 capable: on
DTS capable:on

config.txt:
initramfs initramfs.gz 0x00a00000
gpu_mem_512=256
gpu_mem_256=128
initial_turbo=1
arm_freq=840
core_freq=275
sdram_freq=400
over_voltage=0
hdmi_force_edid_audio=1
config_hdmi_boost=4
disable_splash=1


RE: No Dolby Digital (AC3) audio? - rikardo1979 - 11th Dec, 2013 06:34 PM

does your TV decode AC3 from HDMI and out it to Coax ? just leave XBMC Audio out on 5.1 and external decoders enabled. Than see if you have sound from your TV speakers, it should downmix and play from TV speakers
edit: if this does work and you still have no sound from your amp connected over Coax than its more likely that your TV somehow either does not support this so its not able to out sound from HDMI to Coax or the decoding doesnt work for some reason


RE: No Dolby Digital (AC3) audio? - andoni - 12th Dec, 2013 06:59 AM

(11th Dec, 2013 06:34 PM)rikardo1979 Wrote:  does your TV decode AC3 from HDMI and out it to Coax ? just leave XBMC Audio out on 5.1 and external decoders enabled. Than see if you have sound from your TV speakers, it should downmix and play from TV speakers
edit: if this does work and you still have no sound from your amp connected over Coax than its more likely that your TV somehow either does not support this so its not able to out sound from HDMI to Coax or the decoding doesnt work for some reason

The TV seems to be able to decode AC3 and play it through its speakers. It has the option of sending the downmixed audio thru coax or leave it as passthrough, which is my current setting. The receiver amp recognizes the stream as Dolby Digital and switches to that mode. So I'm guessing the TV is passing through the 5.1 audio correctly. But there is something about the bitstream that is preventing my receiver from decoding it, so no sound comes out or it's garbled. Anyone know if there are any options in xbmc to modify the passed through bitstream, like bitrate, ...etc.??

This might be a general problem with certain old brands of receivers since I've found many people with similar problems: http://forum.xbmc.org/showthread.php?tid=171703

Am I missing something? Or my only option is to buy a new receiver, for me that goes against the logic of buying a low-cost RPi Sad


RE: No Dolby Digital (AC3) audio? - rikardo1979 - 12th Dec, 2013 07:12 AM

hmm, this can be a real pain in ... as the signal is passing the TV so not sure what is happening with it. As you reported that you have a sound from TV speakers that means the signal is coming good out of RPi over HDMI and get messed in TV somehow.
To be honest I do not have a real advise for you I'm afraid.
BTW is this with all movies with DD sound? Can you get MediaInfo of one of the movies which causing this issue ?


RE: No Dolby Digital (AC3) audio? - andoni - 12th Dec, 2013 07:39 AM

(12th Dec, 2013 07:12 AM)rikardo1979 Wrote:  hmm, this can be a real pain in ... as the signal is passing the TV so not sure what is happening with it. As you reported that you have a sound from TV speakers that means the signal is coming good out of RPi over HDMI and get messed in TV somehow.
To be honest I do not have a real advise for you I'm afraid.
BTW is this with all movies with DD sound? Can you get MediaInfo of one of the movies which causing this issue ?

I've tried many movies with DD in my local library or from online streams and they all have the same problem. What I haven't tried is DTS, since some people report that it worked fine even though DD didn't. Do you know a place where I can get DTS sample video?

Also I learned that there were some audio issues fixed with the latest firmware of the pi. Is there a way to upgrade the firmware while keeping the current version of xbian and xbmc? Or do I have to wait until the next version comes out?

Thanks for your help.


RE: No Dolby Digital (AC3) audio? - rikardo1979 - 12th Dec, 2013 07:56 AM

(12th Dec, 2013 07:39 AM)andoni Wrote:  
(12th Dec, 2013 07:12 AM)rikardo1979 Wrote:  hmm, this can be a real pain in ... as the signal is passing the TV so not sure what is happening with it. As you reported that you have a sound from TV speakers that means the signal is coming good out of RPi over HDMI and get messed in TV somehow.
To be honest I do not have a real advise for you I'm afraid.
BTW is this with all movies with DD sound? Can you get MediaInfo of one of the movies which causing this issue ?

I've tried many movies with DD in my local library or from online streams and they all have the same problem. What I haven't tried is DTS, since some people report that it worked fine even though DD didn't. Do you know a place where I can get DTS sample video?

Also I learned that there were some audio issues fixed with the latest firmware of the pi. Is there a way to upgrade the firmware while keeping the current version of xbian and xbmc? Or do I have to wait until the next version comes out?

Thanks for your help.

for testing files you can find most of the if not all formats on http://www.demo-world.eu/trailers/high-definition-trailers.php

Regarding the firmware you can replace just the FW files in the FAT partition - files