[mythtv] Re: ALSA "fixes" actually break stuff in CVS?

[M. S.]

I'll be happy to send whatever information you guys need to help 
troubleshoot this.  First off, I have tried running the program as root and 
it results in the same problem.  I understand the issue with changing the 
mixer settings, and I can get audio to work, but it's only for about 10-20 
seconds.  I think I've seen some other posts on the mailing list about these 
issues, and no one has replied to them anything helpful.  Please help me to 
help you by telling me what you need from me.  Like I said, I'm dead in the 
water right now and I doubt this is just me (because nothing changed besides 
the MythTV Source). :(


Date: Fri, 10 Dec 2004 22:51:04 +0000
From: Ed Wildgoose <lists at wildgooses.com>
Subject: Re: [mythtv] ALSA "fixes" actually break stuff in CVS?
To: Development of mythtv <mythtv-dev at mythtv.org>
Message-ID: <41BA2858.5060806 at wildgooses.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed


>  First, without changing any of the previous settings, I went to watch 
>Live TV and I got a message saying that /dev/mixer wasn't a valid device 
>and couln't be accessed.  After a little research on the dev mailing list 
>archives I see that it said to put "default" as the mixer device.  I also 
>use software-dmix settings and an .asoundrc file so it uses digital audio.


That's because in the past myth couldn't change volume unless you were
using OSS.  Now it supports Alsa for volume and you asked it to use the
volume device /dev/mixer (which I think you will agree is not an alsa
control device).

>  Second, and this is the problem that basically makes Myth unusable, is 
>that after about 20-30 seconds of watching TV... I get WriteAudio: buffer 
>underrrun errors repeatidly until I exit to the main menu.  This causes the 
>video and audio to go into a slow motion convulsion.  I have submitted a 
>bug report because it had worked in all previous versions of myth since .15 
>just fine.  I also reinstalled ALSA just in case and update from 1.07RC2 to 
>the latest release of 1.07 to verify it wasn't something wrong with that.
>
>  Unfortuantly, there is (was) an overwhelming amount of reasons I used CVS 
>over .16 (functionality, features, and fixes).  I know that a lot of work 
>went into supposidly "fixing" ALSA in the current CVS, but I don't really 
>think it has fixed much besides breaking Myth.  I'm not even sure how to 
>troubleshoot or fix this problem at this point.  Anyone have any ideas?


It may well be a different issue.  Quite a lot has changed in the code
since you last updated (besides audio).  Actually the alsa code is not
so different from before, the main change I made was to simplify the
duplicated code in all the output modules into one core place.  A couple
of other people have then submitted changes which are logically correct
to enhance the alsa output.

A lot of problems do stem from the drivers returning incorrect
information to the myth code (which then does stupid things with the
results).  Please try to post more useful debugging code if you really
have a problem (knowing whether running it as root makes a difference
would be interesting, as would knowing whether the OSS driver works better)

Good luck

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