timedemo skips lots of ticks on low-tick rate demos, tells wrong duration

[hoffor]

Description

demos are recorded at whatever tick rate the client is using. for some reason timedemo plays back the demo at an unreasonably fast pace the lower the tick rate was during recording. it doesn't scale linearly and the issue involves timedemo skipping ticks. playdemo doesn't have this issue

for instance: 125 ticks (tickrates at 24) in demo1 250 ticks (tickrates at 48) in a practically identical demo2

with timedemo, demo2 will report that it rendered 155 frames, and demo1 will report only 24 frames. both demos and especially demo1 couldn't even have played all of its ticks, since it only played 24 and 155 frames, and ticks are constrained by framerate. it could be lying, but I'd believe it for demo1 since it's sped up like mad here

in addition, the entire demo does appear to play (beginning is not cut off or anything, like the 'freeze' upon recording may lead one to believe), but for some reason the timedemo output text says the timedemo duration was way shorter than it actually was, eg. 1/2 - 1/8 the actual duration. this applies to both ~5.5s demos in question

so, both rendered frames and duration are reported as suspiciously low values for both demos. i might be inclined to believe the frame value is reported accurately and that it is skipping ticks. the reported duration is definitely lower than actual.

Checklist

• [x] None of the open or closed issues document this problem.
• [x] This is a bug, not a new idea.
• [x] This is objectively a bug, and not something that people commonly disagree on.
• [?] This issue occurs on the latest Team Comtress release, or the master branch.
• [x] This issue occurs on the latest vanilla TF2 update.

• [x] This bug is in the code of the game, not in the textures, sounds, or other resources.
• [ ] This issue is listed on the Source 1 official bugtracker.
• [ ] This issue occurs with DirectX level 100.
• [x] This issue occurs when using no custom content.
• [ ] This issue occurs when using start_tf2.bat (or start_server.bat) with no custom launch options.
• [ ] This issue occurs when using a listen server (using the map command ingame).
• [ ] This issue occurs when using a dedicated server.
• [ ] This bug is in the internal procedures or tooling (e.g. the build process).

Reproduction

1. join listen server and record a demo a few seconds long
2. lower client cmdrate/updaterate by half and record nearly identical demo with same duration
3. timedemo both and observe severe lack of rendered frames, + lower-tickrate demo playing at up to 8x the speed of the other + wrong timedemo duration

Screenshots

Setup Details

Client Settings

• Server or client: client + listen server
• Operating system: win7 lol
• Team Comtress version:
• Custom content:
• Launch options:

Driver Version

• Graphics driver:
• DirectX level:

Hardware Specs

• CPU model: fx-6300
• GPU model: rx 570
• RAM amount: 8gb
• TF2 install location: ssd
• TC2 install location:
• TC2 installation method: