[mythtv] Channel change time

James Courtier-Dutton james.dutton at gmail.com
Sun Jun 6 11:21:02 UTC 2010

On 5 June 2010 13:01, James Courtier-Dutton <james.dutton at gmail.com> wrote:
> Hi,
> I have not improved anything yet, but this is what I have found.
> 1) With my DVB card, the frequency tuning is quick.
> Time from channel change request to first TS packet is 711ms.
> 2) The ringBuffer then waits for 2028ms before it lets any TS packets
> to be processed.
> So, a PAT is not even processed until 2028ms after the first TS packet
> from the newly tuned channel.
> For this entire 2028ms, TS packets are just dropped.
> I believe this is not the ideal way to do things.
> Is there any reason to delay the ringBuffer initialisation at all. Why
> not initialise the ringBuffer at channel frequency tune point?
> I think this would shave 2 seconds off the DVB channel switch time.

I have found out where the 2 second delay is.
    MPEGStreamData *streamData = NULL;
    if (HasFlags(kFlagWaitingForSignal) && !(streamData =
TuningSignalCheck())) {

So maybe this long channel change time is caused by the
"TuningSignalCheck()" function call.
I would have thought that this function should be quick to return, so
I will look into it further.

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