cx88-dvb.c: DVB net latency using Hauppauge HVR4000
PATCH 1/1 cx88-dvb.c: DVB net latency using Hauppauge HVR4000
Hi linux-media developers,
We are from School On Internet Asia (SOI Asia) project that uses satellite communication to deliver educational content.
We used Hauppauge HVR 4000 to carry IP traffic over ULE. However, there is an issue with high latency jitter. My boss, Husni, identified the problem and provided a patch for this problem. We have tested this patch since kernel 2.6.30 on our partner sites and it hasn't cause any issue. The default buffer size of 32 TS frames on cx88 causes the high latency, so our deployment changes that to 6 TS frames. This patch made the buffer size tunable, while keeping the default buffer size of 32 TS frames unchanged. Sorry, I have to use attachment for the patch. I couldn't figure out how to copy and paste the patch without converting the tab to spaces in thunderbird.
drivers/media/video/cx88/cx88-dvb.c +6 -2
@@ -67,6 +67,10 @@ static unsigned int debug;module_param (debug, int,0644 );MODULE_PARM_DESC (debug,"enable debug messages [dvb]" ); +static unsigned int dvb_buf_tscnt =32 ; +module_param (dvb_buf_tscnt, int,0644 ); +MODULE_PARM_DESC (dvb_buf_tscnt,"DVB Buffer TS count [dvb]" ); +DVB_DEFINE_MOD_OPT_ADAPTER_NR (adapter_nr); #define dprintk(level,fmt, arg...) if (debug >= level) \
@@ -80,10 +84,10 @@ static int dvb_buf_setup(struct videobuf_queue *q,struct cx8802_dev *dev = q->priv_data; dev->ts_packet_size =188 *4 ; - dev->ts_packet_count =32 ; + dev->ts_packet_count = dvb_buf_tscnt; *size = dev->ts_packet_size * dev->ts_packet_count; - *count =32 ; + *count = dvb_buf_tscnt;return 0 ; }
will your patch useful for dvb sat tv ?
Quoted 8 lines
We are from School On Internet Asia (SOI Asia) project that uses satellite communication to deliver
educational content. We used Hauppauge HVR 4000 to carry IP traffic over ULE. However, there is an issue with high latency jitter. My boss, Husni, identified the problem and provided a patch for this problem. We have tested this patch since kernel 2.6.30 on our partner sites and it hasn't cause any issue. The default buffer size of 32 TS frames on cx88 causes the high latency, so our deployment changes that to 6 TS frames. This patch made the buffer size tunable, while keeping the default buffer size of 32 TS frames unchanged. Sorry, I have to use attachment for the patch. I couldn't figure out how to copy and paste the patch without converting the tab to spaces in thunderbird.
Hello,
Am Freitag, 24. Dezember 2010 20:28 schrieb Goga777:
Quoted 11 lines
will your patch useful for dvb sat tv ?
Quoted 9 lines
We are from School On Internet Asia (SOI Asia) project that uses
satellite communication to deliver educational content. We used Hauppauge HVR 4000 to carry IP traffic over ULE. However, there is an issue with high latency jitter. My boss, Husni, identified the problem and provided a patch for this problem. We have tested this patch since kernel 2.6.30 on our partner sites and it hasn't cause any issue. The default buffer size of 32 TS frames on cx88 causes the high latency, so our deployment changes that to 6 TS frames. This patch made the buffer size tunable, while keeping the default buffer size of 32 TS frames unchanged. Sorry, I
FWIW in the DVBlast subversion is a similar patch [1] touching the same value. See the reason for this in the README [2].
Tjuess
Heino
[1]http://svn.videolan.org/filedetails.php?repname=DVBlast&path=%2Ftrunk%2Fextra%2Fkernel-patches%2F03-cx88.patch [2]http://svn.videolan.org/filedetails.php?repname=DVBlast&path=%2Ftrunk%2Fextra%2Fkernel-patches%2FREADME