Date: Mon, 19 Mar 2001 18:27:26 +0900 From: Mamoru Iwaki <iwaki@bc.niigata-u.ac.jp> To: freebsd-stable@FreeBSD.ORG Subject: how to use sound device in full-duplex ? Message-ID: <20010319092728.5637.qmail@pikachu.bsp.bc.niigata-u.ac.jp> In-Reply-To: <20010224181126K.iwaki@bc.niigata-u.ac.jp> References: <20010224181126K.iwaki@bc.niigata-u.ac.jp>
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Hi,
I'd like to know the way how I can use sound device in full-duplex.
I want to input sound stream with audio device and immediately
output the stream into the same audio device for playback, without
waiting for the end of input stream. I mean, it should simply make
echoback of input, as fast as possible. For the purpose, I wrote
the following program.
From: Mamoru Iwaki <iwaki@bc.niigata-u.ac.jp>
Subject: sound driver kills kernel silently
Date: Sat, 24 Feb 2001 18:11:26 +0900
> [PROGRAM]
> #include <stdio.h>
> #include <fcntl.h>
> #include <sys/types.h>
> #include <sys/uio.h>
> #include <unistd.h>
>
> #define DEV_IN "/dev/dsp"
> #define DEV_OUT DEV_IN
> #define BUFLEN 1
>
> int main(void) {
> int fdi, fdo;
> char x[BUFLEN];
>
> if ((fdi = open(DEV_IN, O_RDONLY)) == -1) {
> perror("File open failure for read: " DEV_IN);
> exit(1);
> }
>
> if ((fdo = open(DEV_IN, O_WRONLY)) == -1) {
> perror("File open failure for write: " DEV_IN);
> exit(1);
> }
>
> while (read(fdi, &x, sizeof(x)) > 0) write(fdo, &x, sizeof(x));
>
> return 0;
> }
It has worked the last December, but not for now. It causes the
following messages and no sound:
pcm0: record overrun, dumping 8128 bytes
pcm0: record overrun, dumping 8100 bytes
pcm0: record overrun, dumping 8076 bytes
When audio device is opened in read-write mode, it still not works.
Are there any ideas to make the above simple echoback audio program
with full-duplex property.
Thanks.
[ENVIRONMENT]
% uname -a
FreeBSD mi000.merlin.gs.niigata-u.ac.jp 4.3-BETA FreeBSD 4.3-BETA #0: Mon Mar 19 16:32:24 JST 2001 root@mi000.merlin.gs.niigata-u.ac.jp:/usr/obj/amd/mi004/home2/FreeBSD-src/stable4/src/sys/MI i386
% cat /dev/sndstat
FreeBSD Audio Driver (newpcm) Mar 19 2001 16:30:59
Installed devices:
pcm0: <SB16 DSP 4.16> at io 0x220 irq 5 drq 1:5 (1p/1r channels duplex)
---
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Mamoru IWAKI (iwaki@bc.niigata-u.ac.jp)
Graduate School of Science and Technology, Niigata University
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