Frontend Services API GetStatus incorrect if playing live tv or recording

[lilleym]

• Platform: Debian Bullseye
  Linux pi1 5.15.32-v8+ #1538 SMP PREEMPT Thu Mar 31 19:40:39 BST 2022 aarch64 GNU/Linux

• MythTV version: mythtv-light 32~Pre-3360-ga1e72a209b-0

• Package version: Built from source

• Component: Frontend Services API

What steps will reproduce the bug?

1. Start myth frontend
2. Navigate to either live TV, or play a recording.
3. Issue call to Frontend GetStatus api (current code overrides port to 8081, so localhost:8081/Frontend/GetStatus

XML response should indicate that the current location is the playback box, but instead it shows (for live tv) mainmenu.

How often does it reproduce? Is there a required condition?

Always.

What is the expected behaviour?

Current location should indicate playbackbox, with program details available.

What do you see instead?

<FrontendStatus serializerVersion="1.1" version="1.1"> <Name>pi1</Name> <Version>v32-Pre-3360-ga1e72a209b</Version> <State> <String> <Key>currentlocation</Key> <Value>mainmenu</Value> </String> <String> <Key>menutheme</Key> <Value>defaultmenu</Value> </String> <String> <Key>state</Key> <Value>idle</Value> </String> </State> <ChapterTimes/> <SubtitleTracks/> <AudioTracks/> </FrontendStatus>

Additional information

Apparently the network control port shows the correct information (I haven't tested this yet).

[lilleym]

Further testing indicates the network control port does indeed return correct information. The reason the two interfaces react differently appears to be as follows:

When the network control port receives a location query, it calls GetMythUI::GetCurrentLocation which constructs a response based on the current actual status.

When the Services API receives a GetStatus request, it calls MythUIStateTracker::GetFreshState for the status. MythUIStateTracker caches responses for 500ms, but additionally never appears to be notified that the player is active.

I doubt that it's appropriate to be updating the MythUIStateTracker with current position in playback information (for example), especially given the data may never be examined. It seems reasonable to me, to expect it to be notified the player is running, and data about the active playback (once, at startup). I thought I'd open up the question to see if there are other reasonable alternatives.

[thomasboehm]

At some point I got an output where <State> was completely empty

curl 192.168.99.4:6547/Frontend/GetStatus
<?xml version="1.0" encoding="UTF-8"?><FrontendStatus xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.1" serializerVersion="1.1"><Name>desktop</Name><Version>v32.0+fixes.202204301748.d80a8da3f0~ubuntu22.04.1</Version><State/><ChapterTimes/><SubtitleTracks/><AudioTracks/></FrontendStatus>

I can't reproduce it anymore and always get the same output as in the post above.

[bennettpeter]

As a workaround you can use the network control port to get the info until this is fixed

telnet localhost 6546
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
MythFrontend Network Control
Type 'help' for usage information
---------------------------------
# query location
Playback Recorded 00:12:15 of 10:14:02 1x 10001 2022-03-13T19:07:59Z 22032 /home/storage/Video/mythtv-local/Default/10001_20220313190759.ts 29.97 Subtitles: *0:[None]* 1:[ATSC CC 1: Undetermined] 2:[ATSC CC 2: Undetermined] 3:[CC 1: Undetermined]
# exit
Connection closed by foreign host.
peter@rocinante:~$ 

[bennettpeter]

Bug is caused by this line being commented

mythtv/mythtv/libs/libmythtv/tv_play.cpp

Line 2948 in 09fd76c

// customEvent(Event);

Uncommenting that fixes it.
I am waiting for review before making the fix.