[prev in list] [next in list] [prev in thread] [next in thread]
List: linux-kernel
Subject: Re: [PATCH] es1968: fix jitter on some maestro cards
From: Rene Herman <rene.herman () keyaccess ! nl>
Date: 2008-03-31 22:24:43
Message-ID: 47F164AB.5040009 () keyaccess ! nl
[Download RAW message or body]
On 30-03-08 00:49, Andreas Mueller wrote:
> This patch suppresses jitter on several Maestro cards in stereo mode
> (ALSA of course).
>
> The patch is also incorporated in the *BSD drivers where I "ported" it from.
> I am barely used to driver-development so please take a look (esp. the channel
> parameters), nevertheless it completely works for me.
>
> Without this patch most of the stereo audio gets out of sync and really
> distorted (oss-emulation with mplayer at 48000khz worked somehow).
>
> CCed to those listed in the .c file.
Added the alsa-devel list (and re-attached the patch). My TerraTec DMX (ESS
Canyon3D, ES1970MS-3D) doesn't need this but doesn't seem to suffer from it
either. Otherwise no idea about this.
Rene.
["es1968_jitter.patch" (text/plain)]
--- sound/pci/es1968.c.old 2008-03-29 19:17:16.771116317 +0100
+++ sound/pci/es1968.c 2008-03-30 00:14:35.363057160 +0100
@@ -1816,7 +1816,24 @@
return 0;
}
+/*
+ * suppress jitter on some maestros when playing stereo
+ */
+static void snd_es1968_suppress_jitter(struct es1968 *chip, struct esschan *es)
+{
+ unsigned int cp1;
+ unsigned int cp2;
+ unsigned int diff;
+ cp1 = __apu_get_register(chip, 0, 5);
+ cp2 = __apu_get_register(chip, 1, 5);
+ diff = (cp1 > cp2 ? cp1 - cp2 : cp2 - cp1);
+
+ if (diff > 1) {
+ __maestro_write(chip, IDR0_DATA_PORT, cp1);
+ }
+}
+
/*
* update pointer
*/
@@ -1937,8 +1954,11 @@
struct esschan *es;
spin_lock(&chip->substream_lock);
list_for_each_entry(es, &chip->substream_list, list) {
- if (es->running)
+ if (es->running) {
snd_es1968_update_pcm(chip, es);
+ if (es->fmt & ESS_FMT_STEREO)
+ snd_es1968_suppress_jitter(chip, es);
+ }
}
spin_unlock(&chip->substream_lock);
if (chip->in_measurement) {
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic