[mythtv] Digital audio passthrough

Jean-Yves Avenard jyavenard at gmail.com
Tue Sep 14 08:51:29 UTC 2010


On 14 September 2010 18:10,  <mythtv at meric.id.au> wrote:
> Hmmm.. well, in my case it didn't work.

yeah, but it's *your* case, e.g. you're the only one so far :)

> The funny thing is that the device open doesn't actually clear the
> non-audio flag.  It isn't until you set the hw_params (and prepare the
> device), that it gets wiped out.
> Jean-Yves, if you happen to be making changes at some point in the
> future, I think that the snd_pcm_prepare() call in SetParameters() can
> be removed.  My understanding is that the snd_pcm_sw_params() call does
> this implicitly.
> Just out of curiosity - I understand what the AES0 flags do, but what do
> the rest actually mean?  My setup seems to work without them.

The defaults are:

        @args.AES0 {
                type integer
                # consumer, not-copyright, emphasis-none, mode=0
                default 0x04
        @args.AES1 {
                type integer
                # original, PCM coder
                default 0x82
        @args.AES2 {
                type integer
                # source and channel
                default 0x00
        @args.AES3 {
                type integer
                # fs=48000Hz, clock accuracy=1000ppm
                default 0x02

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