[LAU] bit-transparent playback/recoding over AES using an RME 9632 card

[Tino Mettler]

On Thu, 2016-11-17 at 22:26 +0100, Markus Seeber wrote:
> On 11/16/2016 04:17 PM, Tino Mettler wrote:
> > My test setup the card clocked at 48 kHz and the AES input and
> > output
> > looped.
> 
> 
> Which means you connected the digital output to the digital input I
> guess?

Yes.

> Do you count "channel 9 and 10" one or zero indexed? :)
> 
> Here is the channel mapping from the source for reference:
> 
> static char channel_map_H9632_ss[HDSP_MAX_CHANNELS] = {
>     /* ADAT channels */
>     0, 1, 2, 3, 4, 5, 6, 7,
>     /* SPDIF */
>     8, 9,

One indexed.

> Depending on what you "mean" with "the result" this looks perfectly 
> fine
> to me. To be expected of a sampled square wave signal.
> 
> How did you generate the signal?
> How did you measure/visualize the output?

Maybe I was a bit unclear. I generated a square sample and saved it
into a .wav file, as 48 kHz/16 bit/stereo. I expected to see the same
PCM data when recording it.

> If you want to check bit transparency, you need to compare the 
> samples
> of your digital input and output.

I thought I did exactly that, or do you mean I need to compare the
physical signal on the cable?

> I don't see any reason why it would not work if you connect the 
> digital
> output to the digital input.

Actually, a colleague of mine did exactly that in Windows, using
another RME card.

Here are example screenshots of the original and the recording:

https://tikei.de/playback.png
https://tikei.de/recording.png

Regards,
Tino