axfer: add text for compatibility loss of sw parameter in libasound backend

At present, some options for software parameters have actual effects in
cases neither mmap operation nor timer-based scheduling model is used.
For mmap operation, backward compatibility  to aplay(1) is lost.

This commit adds descriptions about it.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/axfer/axfer-transfer.1 b/axfer/axfer-transfer.1
index 4c8e426fcc5c274dd14650f087166bf1bddb6736..272e601adebaa6bd631ab467d2e30e5e285d2a78 100644 (file)
--- a/axfer/axfer-transfer.1
+++ b/axfer/axfer-transfer.1
@@ -684,6 +684,42 @@ effect to use PCM buffer aligned to non\-interleaved order if a target device
 supports. As of 2018, PCM buffer of non\-interleaved order is hardly used by
 sound devices.
 
+.TP
+.I \-A, \-\-avail\-min
+This option indicates threshold to wake up blocked process in a unit of
+audio data frame. Against aplay(1) implementation, this option has no effect
+with
+.I \-\-mmap
+option as well as
+.I timer
+of
+.I \-\-sched\-model
+option.
+
+.TP
+.I \-R, \-\-start\-delay
+This option indicates threshold to start prepared PCM substream in a unit of
+audio data frame. Against aplay(1) implementation, this option has no effect
+with
+.I \-\-mmap
+option as well as
+.I timer
+of
+.I \-\-sched\-model
+option.
+
+.TP
+.I \-T, \-\-stop\-delay
+This option indicates threshold to stop running PCM substream in a unit of
+audio data frame. Against aplay(1) implementation, this option has no effect
+with
+.I \-\-mmap
+option as well as
+.I timer
+of
+.I \-\-sched\-model
+option.
+
 .TP
 .I \-\-max\-file\-time=#
 This option is unsupported. In aplay(1) implementation, the option has an