AC3 passthrough support

Second version after Tanu's feedback

TODO:
    - notify client that volume control is disabled
    - change sink rate in passthrough mode if needed
    - automatic detection of passthrough mode instead of hard
    coded profile names

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/PROTOCOL b/PROTOCOL
index 883b8bb65..f180b96d5 100644
--- a/PROTOCOL
+++ b/PROTOCOL
@@ -194,3 +194,9 @@ new messages:
 new flag at end of CREATE_PLAYBACK_STREAM:
 
     bool relative_volume
+
+## v18, implemented by >= 0.9.22
+
+new flag at end of CREATE_PLAYBACK_STREAM:
+
+    bool passthrough