Opened 6 months ago

Last modified 4 months ago

#13554 assigned Bug Report - General

FPS drops to 4 or few per second and audion sync lost when there is transmission corruption

Reported by: bib1963 Owned by: Mark Kendall
Priority: minor Milestone: needs_triage
Component: MythTV - General Version: Master Head
Severity: medium Keywords:
Cc: Ticket locked: no

Description

When I view terrestial transmission, my connection is not great so I occasionally get errors.

When an error does occur, the fps from from 50 to around 4.

If I pause then unpause, the fps increases to 100+, then once it catches up, it reverts back to 50.

With the corruption though, lipsync is lost.

Attachments (1)

mythfrontend-20200130-2.txt.zip (84.4 KB) - added by bib1963 5 months ago.

Download all attachments as: .zip

Change History (6)

comment:1 Changed 6 months ago by Mark Kendall

Status: newinfoneeded_new

We are going to need far more information.

  • full logs from mythfrontend -v playback
  • if possible, a clip that reproduces the behaviour (can you cut the relevant portion from a recording that is corrupted?)

comment:2 Changed 6 months ago by bib1963

This could take a long time and giving a clip won't work.

The reason it does not work, is when you go into live recording to review, you find that the clip is presented correctly, at least to a point.

I am hazarding a guess that it is either due to a general playback bug, or it is due to the FE catching up on the buffer.

There has always been a buffer catchup problem. My monitor is 59.95fps, where as, here in the UK, we are on 50/25fps. I assume there is a problem here.

Regardless though, there is still a problem with audio sync. The video starts to trail the audio. It's that bad after 10 minutes, that you have to stop and restart the view.

comment:3 Changed 5 months ago by bib1963

Finally got it to happen with live tv.

For the A/V issues, it's as if the FE, is saying it is behind and is correcting it, without actually doing so, or possible instead of subtracting, it adds or vice versa. This happens with recording as well.

Regardless, there is a total lack of rendezvousing between video & audio. It may think there is, but it's does not appear to be actually doing anything.

My system is only a 2C/4T, and it may also be that the cpu's are busy doing other things and the FE is not aware.

For the last 5 minutes of the log, the video went down to around 2FPS. The audio played normally.

I ended up pausing it, then unpausing it, whereupon the video raced through to catch up before settling down, but the audio was still massively out of sync. This could be caused by the FE getting ahead of the data, in that it tries to extract data from the buffer, but the card has not yet supplied it.

At the end of the log, the audio was around 10 seconds ahead of the video.

Sending the recording though vlc, shows no problems.

The audio sync issues are also caused by a corrupted transmission.

Changed 5 months ago by bib1963

comment:4 Changed 5 months ago by bib1963

And this was on the sat connection...

comment:5 Changed 4 months ago by paul-h

Owner: set to Mark Kendall
Status: infoneeded_newassigned
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