[mythtv-users] problems with AC3 passthrough
Brandon Beattie
bbeattie-maillist at linkexplorer.com
Thu Feb 26 15:35:54 EST 2004
Hi Bo,
I see that problem at times on my system. What I found is it's most
likely a bug with alsa. I have a copy of my /etc/asound.conf file that
I copy back to the correct location and re-run alsactrl. It appears
sometimes when you shut down, alsa re-writes the file incorrectly and
ac3 doesn't work right when you boot. I recommend re-runing the alsa
configuration tool (Or if you manually edited the asound.conf file to
enable spdif for your sound card, re-edit it and run 'alsactrl restore'
again. I use some mp3's to test this. I know of some songs that the
first instant of them that there is music. If I hear a split second of
audio and it cuts out, I do my little routine and run-run mpg123 and
audio is just fine. Give it a try. If not, let me know. I'll try to
watch for your thread but I normally now just browse this thread in
digest mode so mail me if I don't answer. ;) I'll be only able to
answer from work now as my htpc blew out (I have yet to see if my 3
hdtv cards still work) I just ordered the antec overture case and I'll
post how quiet and well it works. Lets hope it was just the power
supply...
--Brandon
> ------------------------------
>
> Message: 8
> Date: Thu, 26 Feb 2004 10:52:25 -0600
> From: myth at najdrovsky.com
> Subject: [mythtv-users] problems with AC3 passthrough
> To: mythtv-users at mythtv.org
> Message-ID: <200402261652.i1QGqPoF019908 at mortisha.najdrovsky.com>
>
> Hi all, first time poster here, but have been browsing the archives for a
> while. I've got my HDTV myth set up almost working, but I've not been able
> to get the AC3 passthrough to work. If I disable it, I get PCM audio through
> the S/PDIF port and hear it through my stereo, but it's choppy since the
> computer has to decode both HighDef video and the AC3 stream. What this
> does, at least, is confirm that I'm able to reach the digital output connector
> and send out the data. Unfortunately, when I check off the passthrough, the
> AC3 stream appears to be sent for a split second, and then it's nothing but
> silence. The reason I know that the first few bits of the AC3 stream make it
> through is because I hear a split second of audio, and my receiver's display
> lights up the AC3 letters.
>
> My configuration is as follows:
> Hardware:
> * Chaintech 7NIF2 motherboard with the optional S/PDIF I/O bracket. This board
> uses the nVidia nForce2 chipset and also has the CMedia 9738 sound chip,
> which appars to be intel8x0 compatible.
>
> * pcHDTV hidef tuner card
> * ALSA 1.0.2
>
> The audio output device in myth is configured to ALSA:hw:0,2
>
> Could someone please provide some suggestions as to what I need to do to get
> the AC3 stream to work correctly? BTW, please don't tell me to switch to OSS,
> because I don't get any sound at all via OSS.
>
> thanks,
> Bo Najdrovsky
>
> p.s. Here is a tip for those with HDTV sets, nVidia's 1.0-5610 video driver
> supports interlaced video, so I'm able to get a nice 59.97Hz 1920x1080i video
> output on my high def TV. The video overlay works fine in this high resolution
> also.
>
>
> ------------------------------
>
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> End of mythtv-users Digest, Vol 13, Issue 145
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