Re: [Embedded-pv-devel] [Xen-devel] [PATCH v8] This is ABI for the two halves of a Para-virtual sound driver to communicate with each to other.

[David Vrabel <david.vrabel@xxxxxxxxxx>]

Sound is not my area of expertise but I have a few points that you may
like to consider.

1. You can only say how many channels a stream has, not what the
channels correspond to (e.g., "left", "right" for a 2 channel stereo
stream; or "left-front", "rear-right", etc. for a 6 channel 5.1 surround
sound stream).

2. Volume control uses absolute power levels (dBm). How is this supposed
to map to the standard 0-100% volume controls that are most commonly
presented to a user?

3. For the PCM formats you need to precisely specify the format or
reference external specifications that do so.  For example, "mpeg" is a
bit vague as I'm sure this standard body has produced many different
audio formats.  The specifications don't need to be freely available,
just correctly referenced.

4. 8 bits for stream index, operation and (particularly) pcm format feel
a little limiting.

5. For the read/write operations is the stream buffer considered to be
circular?  I think it probably should be.

6. PCM_FORMAT_SPECIAL doesn't seem useful to me.  New formats should be
added via an update to this spec.

David


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