From 1919de0a9e939ef4f9453ef1630ca1345991e144 Mon Sep 17 00:00:00 2001 From: Alan Horstmann Date: Mon, 4 Jun 2007 23:11:23 +0200 Subject: [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 Signed-off-by: Takashi Iwai Signed-off-by: Jaroslav Kysela --- Documentation/sound/alsa/OSS-Emulation.txt | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'Documentation/sound/alsa') 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 ==================== -- cgit v1.2.3