[iptv-users] Causes of jitter

[Dan White]

On 04/12/10 16:40 -0600, Frank Bulk wrote:
>One of our Calix rings is experiencing some very short video freezing (no
>perceptible interruption in the audio).  It appears to happen on all Calix
>nodes in that ring and appears to be regardless of channel.  Sometimes it's
>worse (almost unwatchable) and sometimes we get no complaints for days.
>Selective analysis of customer Calix ports counters show clean or very few
>errors, definitely nothing that I can attribute to physical plant.

What technology is it happening on? If ADSL, you might experiment with your
latency depth, assuming that the jitter was due to some problem on
the local loop.

>I watched one hour of programming Friday morning at a customer and counted
>15 freezing events, all of them but one very short.  We don't have any
>formal testing gear (yet), but a borrowed JDSU T-Berd is showing occasional
>jitter (up to 18 msec, sometimes 5 msec) and both the T-Berd and TS-Reader
>are showing identical Continuity Counter counter values.

You might ask your middleware vendor to check or verify the jitter buffer
size on your STBs.

>Sometimes the freezing is accompanied by the CC going up by two (one for
>audio, one for video), other times the freezing doesn't have any change to
>CC, and sometimes the CC goes up and we don't perceive any freezing.
>
>I would like any and all input on:
>a) possible sources of the freezing

Other possibilities of freezing might be due to DHCP lease change or IGMP
timeouts.

We've also seen encoder settings, and HDMI incompatibility (you might
verify it's happening on component) cause random freezes.

-- 
Dan White