At Tue, 01 Apr 2008 00:24:43 +0200, Rene Herman wrote:
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.
This should depend on the sample rate you use. 48k would work without the patch.
Anyway, I applied it to ALSA tree now. Thanks.
Takashi
Rene. [2 es1968_jitter.patch <text/plain (7bit)>] --- 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);}