[alsa-devel] Proper way to set SCMS copy prohibited bits on IEC958 S/PDIF

Andrew Paprocki andrew at ishiboo.com
Thu Jul 31 02:03:40 CEST 2008

On Wed, Jul 30, 2008 at 8:01 PM, Rene Herman <rene.herman at keyaccess.nl> wrote:
> On 30-07-08 22:37, Andrew Paprocki wrote:
>> I briefly checked the code for the Delta1010 (ice1712) to see if there
>> was a way from user space to force the SCMS copy prohibited bits on in
>> the S/PDIF stream. I see the driver initializes the bits to 0. Is
>> there already a way to do this from user space, or would I have to
>> modify the driver to force them on (or use a module parameter)?
> I can't try this myself right now, but try "man iecset".

I actually found this code as well: http://www.cs.tut.fi/~ik/mpegspdif/output.c

It appears you can set the bits when opening the card by using a
device string like this:

sprintf(devstr, "iec958:AES0=0x%x,AES1=0x%x,AES2=0x%x,AES3=0x%x",
s[0], s[1], s[2], s[3]);

I'll look into both methods.

Thanks, -Andrew

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