TTL or DNS resolve buggy, leads to VLC crashing

[mkdr]

Hello,

I have the following issue since forever with VLC. I can reproduce this with 90% chance if I let a live stream run. Over time, VLC will just force close or get stuck and you cant close it anymore but via task manager (Windows).

I hav reported this issue several times, but no VLC dev ever was interested in looking into this.

To me, the issue seems to be the name resolver of VLC, being "too picky". Either the time window is too strict or there is some strange bug with it.

The issie is, when watching a live stream, for example a twitch.tv live stream via an m3u8 file. The packets of the stream are reloaded and also resolved every 5-10 seconds or so, and with every resolve, there is a chance, VLC will crash. If I watch over LAN it never happens (happened too sometimes, but really really rare). But it happens often over WLAN. It seems to me, the higher the "chance" for a packet loss, the higher the chance VLC will crash when it wants to resolve.

Looks to me that the current implementation of resolving hosts and/or connecting to hosts is buggy or badly optimized/programmed in the following way

- seems VLC just will resolve 1 time, not trying more, if the one resolve or connect fails, it will close the stream and close itself (and then also crash with a high chance)
- seems there is no DNS cache, it resolves the same host every single time

The crash thing is another issue which I can reproduce with this very often. VLC will just stay in systray and wont be able to close via exit/close just via kill in task manager. This doesnt happen everytime, but very often, after a DNS resolve fails and VLC stays open with black screen and cant be closed anymore, even the GUI is responding.

Is there maybe some console command or some hidden option for TTL or retries of DNS resolve in the VLC settings?

How to extract m3u8 for a twitch.tv live stream: https://pwn.sh/tools/getstream.html

[unidan]

Hi, if I understand right, it's a known issue in the adaptive HLS access-demux, and not in the DNS resolver.

[Rémi Denis-Courmont]

VLC uses the system's DNS resolver. I don't know if that's too picky and/or lacks caching, but it's not part of VLC.

[mkdr]

This bug is still present after all these years in VLC 3.0.20.

Easy to reproduce:

- Open a video m3u8 stream in VLC, for example a twitch stream
- force a disconnect behind the PC, for example just drop the connection on the router
- VLC will now "crash" with high chance and enter a buggy "stuck state", not always, but with high chance. you cant close VLC anymore, systray icon is stuck, clicking exit in systray doesnt do anything

Only way to close VLC is force close the process via task manager or taskkill.

[Rémi Denis-Courmont]

You stated up-front that it is a bug in the DNS resolver. Since the DNS resolver is part of your Windows OS, and not of VLC, it should come to as no surprise that no attempt to fix the problem is forthcoming from VLC developers.

Besides, this is a volunteer project. If you are not satisfied with the development process, you are more than welcome to contribute a fix yourself (or pay someone else to do so).

[mkdr]

Video recordings you initiated in VLC with live streams are also corrupt if the connection drops and VLC not properly closing/finishing the recording, which is another connected bug to this one while the recording happens. Please stop debate if it is DNS issue or not. So yes it is not DNS related, I just assumed it was when I opened this post 2019. It is something else and a bug in VLC since over 10 years or mostly from the beginning of VLC. Clicking stop doesnt help in this case, video file is now corrupt and cant be used anymore even it recorded x amount of data to disk.

And another third bug to this, it happens often not always, that VLC restarts (video window rescales back if this happens, video recording also breaks), for the first moment of the m3u8 first part finishing and loading the next one. After this it goes on normally.