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authorAlan Horstmann <gineera@aspect135.co.uk>2007-06-04 23:11:23 +0200
committerJaroslav Kysela <perex@suse.cz>2007-07-20 11:11:23 +0200
commit1919de0a9e939ef4f9453ef1630ca1345991e144 (patch)
tree019b662d29a7f6c278c4ea6f4ad8bbd562bf74f6 /Documentation/sound
parent3b194401a31b8df9a07a1850e3fe44fc7ba832a4 (diff)
downloadlinux-1919de0a9e939ef4f9453ef1630ca1345991e144.tar.bz2
[ALSA] More description on duplex streams with OSS emulation
Add paragraph to the OSS document to clarify correct use of duplex streams. Signed-off-by: Alan Horstmann <gineera@aspect135.co.uk> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jaroslav Kysela <perex@suse.cz>
Diffstat (limited to 'Documentation/sound')
-rw-r--r--Documentation/sound/alsa/OSS-Emulation.txt15
1 files changed, 15 insertions, 0 deletions
diff --git a/Documentation/sound/alsa/OSS-Emulation.txt b/Documentation/sound/alsa/OSS-Emulation.txt
index ec2a02541d5b..bfa0c9aacb4b 100644
--- a/Documentation/sound/alsa/OSS-Emulation.txt
+++ b/Documentation/sound/alsa/OSS-Emulation.txt
@@ -278,6 +278,21 @@ current mixer configuration by reading and writing the whole file
image.
+Duplex Streams
+==============
+
+Note that when attempting to use a single device file for playback and
+capture, the OSS API provides no way to set the format, sample rate or
+number of channels different in each direction. Thus
+ io_handle = open("device", O_RDWR)
+will only function correctly if the values are the same in each direction.
+
+To use different values in the two directions, use both
+ input_handle = open("device", O_RDONLY)
+ output_handle = open("device", O_WRONLY)
+and set the values for the corresponding handle.
+
+
Unsupported Features
====================