triggerhurt
Posts: 11
Joined: Tue Mar 13, 2012 12:02 pm

Analog Audio XBMC low volume AC3

Thu Jul 12, 2012 11:16 am

Hi everybody,

I was able to compile xbmc as described on the raspbian page (pisces) and it's working fine so far! Your work is very much appreciated and I will definitely stay with raspbian for various reasons! I have one problem so far (which isn't solved on raspbmc and openelec too) and thats the xbmc ac3 sound over the analog output. It has got way to low volume and I can't raise it (and btw the audio on xvids (mp3) could use some more headroom too). I can raise the volume of the tv (Im running a euro PAL analog tv) but that leads to slight distortions/noises. The provided signal is just too weak!

Things I tried:
- Increase the normal xbmc volume
- Increase the "super-" volume in the audio settings during playback (no effect at all)
- play around the advancedsettings.xml audio settings: ac3downmixgain + headroom (no effect at all)
- /etc/asound.conf:
pcm.!default {
type hw
card 0
}

ctl.!default {
type hw
card 0
}
- alsamixer aumix ("cannot open mixer: No such file or directory" / "error opening mixer: No such file or directory")


Any suggestions? Is this a known problem being worked on? I need help! :cry:

masterluke
Posts: 200
Joined: Tue Apr 17, 2012 4:10 pm

Re: Analog Audio XBMC low volume AC3

Thu Jul 12, 2012 1:01 pm

I haven't got an answer for you, but I have noticed the same thing so its not just you. I just turn the tv volume right up. I have also come across a similar situation with other devices which convert digital audio formats to analog, my freesat box is way quieter on a channel with DD than one one with regular stereo. I'm not sure there will be an easy answer because upping the volume will probably also introduce noise. I suspect regular-XBMC will behave the same.

User avatar
mpthompson
Posts: 620
Joined: Fri Feb 03, 2012 7:18 pm
Location: San Carlos, CA
Contact: Website

Re: Analog Audio XBMC low volume AC3

Thu Jul 12, 2012 4:15 pm

Sorry, I can't suggest anything here. Sound under Linux is still a bit of a mystery to me. I would suspect there is probably a gain value in one of the configuration files that isn't set correctly. Could also be an XBMC config issue as well. There is another thread where folks are discussing getting ALSA working with Raspbian. Perhaps they would have some advice on getting analog sound working better with XBMC.

http://www.raspberrypi.org/phpBB3/viewt ... =66&t=7107

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5370
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: Analog Audio XBMC low volume AC3

Thu Jul 12, 2012 4:50 pm

Be aware that XBMC doesn't use ALSA for audio when playing video. (depending on build, it might use ALSA for music).
I'm guessing it is a problem with mixing multiple channels down to stereo. In general a mixing process loses amplitude.
I believe there is a "boost volume on downmix" setting in XBMC. Make sure that is enabled. However it is possible that has no effect (try turning it on and off - any difference?) which may be the real problem.

triggerhurt
Posts: 11
Joined: Tue Mar 13, 2012 12:02 pm

Re: Analog Audio XBMC low volume AC3

Fri Jul 13, 2012 12:15 am

Thanks for the replies so far! I thought there is used some way without alsa because it was disabled on purpose on the build instructions http://www.raspbian.org/RaspbianXBMC.

I indeed tested the existing "boost volume on downmix" option (now again) and it has no effect though.

However I experienced that sometimes (rare) some audio (i guess one of the downmixed channels) in a movie (ac3) is remarkable louder (~better) than the rest. To be more precise i guess there are basically two problems:

1. The maximum possible generic sound output (e.g. mp3 audio lines) is a bit low (but quite acceptable - hey it's beta!)
2. The ac3 (oh and it's dts too) stereo downmix to analog isn't working properly = very low volume (which has a possible connection to nr. 1)

I don't think it's power related because I got a 1000mA supply and a (active) powered usb hub and I don't think the cpu is overloaded because audio and video are performing without stuttering (video after few seconds audio right from the start) and responsive.

Is it a good idea to search for the responsible code and raise some figures? I'm not that bad in c++ but i guess audio programming is a thing of its own, isn't it? I read sth about a standard setting of the raspi onboard card reader clock which was set too low for normal/expected speeds. Could sth like this be the case with the analog audio jack, too?

Josh.43
Posts: 12
Joined: Tue Jun 26, 2012 3:26 pm

Re: Analog Audio XBMC low volume AC3

Sat Jul 14, 2012 8:17 pm

If XBMC does not use ALSA, what does it use?

I think that a hack to tell XBMC to process the the front channels (adding the centre channel to both sides) and output just that to left and right stereo would go a long way towards fixing the volume issues, especially the loss of voice issues.

Info
Posts: 1
Joined: Tue Jul 17, 2012 8:42 pm

Re: Analog Audio XBMC low volume AC3

Tue Jul 17, 2012 8:48 pm

Hello all, same problem with analog audio here, it is realy low volume and you can hear distortion when navigating the xbmc menu.

What can be the problem? Thanks.

triggerhurt
Posts: 11
Joined: Tue Mar 13, 2012 12:02 pm

Re: Analog Audio XBMC low volume AC3

Wed Jul 18, 2012 5:29 pm

I guess it's a bug... I posted sth in the xbmc forum. If you got this bug too or helpful info please leave a short msg there. I hope there are the right people and they get interested in fixing this quite annoying bug...

http://forum.xbmc.org/showthread.php?tid=136309

If this isn't working I am going to post a bug in their bugtracker if it isn't posted already until then...

best regards

trigger

Broccoli
Posts: 12
Joined: Wed Dec 26, 2012 11:49 am

Re: Analog Audio XBMC low volume AC3

Mon Jan 07, 2013 2:03 am

I am also experiencing fairly low volume on my headphones. Is it too much to ask to just have a control to increase the volume?? I just wanna watch a movie :cry:

kalehrl
Posts: 350
Joined: Tue Jul 24, 2012 10:49 am

Re: Analog Audio XBMC low volume AC3

Mon Jan 07, 2013 10:34 am

Volume control already exists.
See this post:
http://www.raspberrypi.org/phpBB3/viewt ... 64#p250864
Maybe you should sudo reboot in the end for good measure.
I have mine set to 64% from the default 44%.
This is for Raspbian. It seems it won't work with XBMC according to posts above.
Sorry.

Broccoli
Posts: 12
Joined: Wed Dec 26, 2012 11:49 am

Re: Analog Audio XBMC low volume AC3

Mon Jan 07, 2013 3:51 pm

kalehrl wrote:Volume control already exists.
See this post:
http://www.raspberrypi.org/phpBB3/viewt ... 64#p250864
Maybe you should sudo reboot in the end for good measure.
I have mine set to 64% from the default 44%.
This is for Raspbian. It seems it won't work with XBMC according to posts above.
Sorry.
Not sure how that can help for XMBC volume troubles. There is a volume control but it only seems to let you lower the volume from the default 0db, which is usually pretty quiet and unusable for a movie. Is there a media centric image for Raspberry Pi that allows for real volume boost?

elrafaargentino
Posts: 4
Joined: Tue Jul 30, 2013 8:34 pm

Re: Analog Audio XBMC low volume AC3

Wed Jul 31, 2013 11:53 pm

I have the same problem, but with some videos (maybe codecs). Im using raspbmc and I listen youtube videos fine and some mp4 (from pen) badly (as an example).

I would like to "power" the volume with a kind of gain (like winamp does) or something like that.

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5370
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: Analog Audio XBMC low volume AC3

Wed Jul 31, 2013 11:57 pm

elrafaargentino wrote:I have the same problem, but with some videos (maybe codecs). Im using raspbmc and I listen youtube videos fine and some mp4 (from pen) badly (as an example).

I would like to "power" the volume with a kind of gain (like winamp does) or something like that.
Try here for volume above 100%
http://forum.xbmc.org/showthread.php?ti ... pid1421472

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