[mythtv] Patch: Big audio code update (please test)

[David George]

On 10/8/2004 9:16 AM, Jesper Sörensen wrote:

> Ed Wildgoose skrev:
>
>>> I've done some testing with your patch and OSS output seems to work 
>>> nicely (as before). The native ALSA support is very unstable but it 
>>> wasn't stable before your patch either so that's no loss. I'm 
>>> looking forward to and will test more after David George's ALSA patch.
>>
>> Thanks for testing.  What kind of alsa problems are you getting?  
>> Card and symptoms please?  Any debug info?
>
> The first error I saw was a crash with an assertion error somewhere 
> deep down in Alsa. I did run it through gdb but there was lots of 
> debug symbols missing or something so I didn't get much wiser. I think 
> my Myth was compiled with debugging but I might be wrong, or perhaps I 
> need to recompile Alsa with debugging too. Will mess with it later.
>
> I'm currently running Alsa driver 1.0.4 (included in Linux 2.6.8) and 
> the Debian Alsa libs/utils which are currently at 1.0.6[a]. The card 
> is a M-Audio Revolution 7.1 (ice1724). I'm on a DVB sat feed here so 
> the audio comes in different formats on different channels (and even 
> changes between programmes), and I guess those of you using analog TV 
> cards always get the same audio format from the card?
>
> I'd like to help fix the Alsa bugs but let's wait for David's patch 
> first so we don't do double work. With your cleanup patch I'm sure 
> it'll be a bit easier to debug the audio code though! :-)

I don't know why, but I have only had really good results using ALSA 
1.0.5a with libs/utils of 1.0.5.  I was able to improve the Myth ALSA 
code enough that it now works with 1.0.7 CVS.  I will test my changes 
with the released 1.0.5 and 1.0.6 also to make sure I don't break 
anything for a majority of the users.

Patch should be coming soon.  I was able to get a lot done last night 
and will be working on it more tonight when I get home.  I have added 
the volume control support to the AudioOutputBase and 
AudioOutput{oss,alsa} classes.  I am having a little difficulty with 
changing tv_play.cpp over to the new volume control.  My C skills are 
very strong, my C++ skills not quite there yet (too many years of C 
programming has corrupted my brain ;-) ).

>> The alsa support is likely to be driver problems rather than the myth 
>> alsa code to be honest.  But we can try to work around stuff here.  
>> Does mplayer work ok for you via Alsa?
>
> Yes, Alsa works with mplayer and xine. But as I said, I don't think my 
> Alsa problems are caused by your patch since it has never been stable 
> here. The OSS output works great though (I'm using Alsa's OSS emu, 
> with digital out) so I'm not sitting on a sinking ship here...
>
>>> May I ask why it needs to be a Myth lib? Wouldn't it be easier to 
>>> get it via the official channels? Debian pkgs exist, you say it's in 
>>> Gentoo and there are RPM:s too (don't know if they are "official" 
>>> though).
>>
>> Happy to go either way.  However if it's included in the Myth package 
>> then you don't *need* to install anything to make your binaries work 
>> fine...
>>
>> Otherwise I need to make the resample bit a compile time option you see.
>
> Ok, I was just wondering. :-)

Don't know if it would apply to this, but in the past Isaac has said 
that he doesn't want to add any additional dependencies to Myth.  
libsamplerate is a small enough library and doesn't seem to change 
extremely often so shouldn't be a problem adding it to Myth.

I have already converted libsamplerate to be compilable as a myth 
library (in the Myth framework - no more ./configure).

--
David