[mythtv] [mythtv-commits] Ticket #5900: AO: Generalise upmix and AC-3 encoding

John P Poet jppoet at gmail.com
Wed Nov 12 07:49:42 UTC 2008

On Tue, Nov 11, 2008 at 10:32 AM, foo bar <foobum at gmail.com> wrote:
> 2008/11/11 Dave Badia <dbadia at gmail.com>:
>> I'm also doing the whole "bit perfect audio" thing.  So, if I'm
>> understanding correctly, when I upgrade to head/next myth release I will
>> need to apply the above patch (which removes one of the features of the
>> original patch)  to continue getting 44.1KHz output through my soundcard?
> This is configurable in the latest version of the patch - if you're
> confident that ALSA isn't going to resample (twice) and have
> appropriate hardware you can add a setting 'DisableResampler' with
> value 1 to the db.
> For the vast majority it's far better that we resample - SRC anywhere
> else in the chain (ALSA, card) would be done with a SNR much less than
> a *worst case* 97dB..
> To set the setting:
> echo "insert into settings values ('DisableResampler', 0, '<hostname
> of frontend>')" | mysql -u mythtv -p mythconverg

Just as a note....

A couple of years ago I really wanted to just be able to use the
on-board sound in my mythfrontend.  While it sounded fine for TV and
Movies, there was a noticeable degradation when playing music.  At the
time I was an audiotron user, and the difference in audio quality was

After some research I went out and bought a ice1712 based sound card.
At the time is was a PITA to get working, but once I did, it pretty
much solved the audio quality problem.  To get it working, I had to
use a custom .asoundrc file.

With modern ALSA, my ice1712 based sound card is just plug-n-play.  No
.asoundrc file necessary at all.  Foo managed to make me paranoid that
ALSA might actually be re-sampling 44.1KHz into 48KHz, and maybe I had
not noticed the drop in quality - since I have not used my audiotron
in so long.  A little searching and I found this:


The page he links to in that article has 44.1KHz DTS encoded wave
files.  If you try and play them on a soundcard that is being
re-sampled to 48KHz, you apparently get static.  On my system, I get
the appropriate sound effects, which is suppose to prove that I am
getting bit-perfect 44.1KHz audio.  If someone with a soundcard that
does require 48KHz could try this test, I would appreciate
confirmation that the test is valid.

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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