[mythtv-users] Livetv freeze with HDPVR

HP-mini blm-ubunet at slingshot.co.nz
Thu Jun 2 19:04:11 UTC 2016

On Wed, 2016-06-01 at 19:45 +0000, John P Poet wrote:
> On Wed, Jun 1, 2016 at 12:34 PM HP-mini <blm-ubunet at slingshot.co.nz>
> wrote:
>         On Tue, 2016-05-31 at 03:14 -0500, Rajil Saraswat wrote:
>         >
>         > > LiveTV on an HLS channel just crashes the FE on the hour &
>         half
>         > hour.
>         >
>         > Likewise this occurs every 30 minutes although the FE does
>         not crash.
>         > Is there anyway to improve this?
>         >
>         LiveTV on normal OTA dvb works okay here (I think) except for
>         the
>         navigation weirdness after resume from pause.
> Sorry, I have not been following this thread, so this may have already
> been mentioned.
> Latency on HDPVR and HLS is going to be very high compared to other
> sources.  For example, the HDPVR generated keyframes every 2 seconds.
> Other broadcast sources will have a keyframe every 0.5 seconds.
> Myth's LiveTV code is not optimized for such long delays and it causes
> issue.
> Every few of years, someone typically steps up and tries to make
> Myth's LiveTV code more robust.  They make a few improvements and then
> it gets set aside again.  LiveTV is a bit of an after-thought, and it
> is unlikely to ever work as well as recording.  That being said, I am
> willing to answer any questions about that part of the code, if
> someone wants to take another stab at it.
> John

The HDPVR output bitstream is configurable only via a windows tool.
That part was never implemented in linux driver code.
The default HD output has IDR keyframe every 128 frames & seekable
recovery point keyframes every 16? .

That navigation weirdness is playing the wrong part/time of sequence
after a long pause.

The HLS crash is in the TFW & low bitrate support code.
It is possible the HLS LiveTV crash involves the strange incorrect
recording state for the exact period of one minute after recording
stops. Wondered is this is due to 10 sec timeout on attempting to read
from write buffer instead of direct from disk. Possibly pausing for over
1 minute might stop the crash, I try that.

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