Note: this website forced me to select an operating system so I selected Android, but this is actually ChromeOs, on my laptop which I bought specifically for the purpose of casting in this way.
So on my new Chromebook laptop I can cast a chrome tab fine - works without any issues. If I attempt to cast the desktop to the same TV with the same Chromecast dongle (I believe it is a v1), I get horrendous audio corruption that makes it unusable.
My phone, my deskop, other phones etc can all cast VLC or mirror screen to the TV with this exact same chromecast dongle without any issues.
Clearly the problem is when casting the desktop, but googling this issue is pretty useless and just brings back lots of generic tips like "restart your chromecast" and "change HDMI port the chromecast dongle is plugged in to". I tried fiddling around with the audio / video settings of the Chromecast dongle on google home, I've tried changing the cast settings in VLC, I've set the audio to be handled by the TV within VLC, and I've forced both the laptop and dongle to be on the same 2.4GHz wifi connection (rather than 5GHz + 2.4GHz), but none of this worked.
I can open the exact same file from within Chrome using Ctrl + O shortcut, however it doesn't give me any video, just the audio when I do this, hence the need for the VLC app. When in this mode I can then cast this Chrome tab on to my TV, and it plays the audio crystal clear - again without any video.
VLC can similarly play the audio and video on the Chromebook display only without any issues, but as soon as I try to cast the desktop (because VLC ChromeOS app doesn't have it's own cast option) the sound is garbled. So I don't believe there is anything wrong with the media file itself.
As it is clear that the issue is from casting desktop on ChromeOS only and casting a tab works fine (which does not let me cast locally stored videos on the device using VLC app), most suggestions I see I haven't even bothered attempting because it's clear they aren't desktop-casting specific and that is the issue I am having.
Thanks for reaching out. Please try to reinstall the Chrome browser and restart your Chromebook. Resetting your Chromecast might also help.
Note: You can display your entire computer screen using Chrome on Mac, Windows, and Chrome OS but to play the audio on your TV, use a Windows computer. See the info here.
How do I reinstall Chrome on a Chromebook? That sounds pretty weird.
1. I bought a new chromecast 3 and put it on the same TV. Same result, so we can rule out the v1 chromecast being the problem. I have a second TV but haven't tried casting to it as at this point I am 99% sure it is a software issue on the chromebook. For my specific use case it doesn't really matter - if it can't cast media to the TV in my bedroom then it doesn't matter if it works on the lounge TV.
2. I had enabled the experimental desktop launcher feature for the chromebook, so I turned that (and a couple of other flags) off. No change.
3. Because this was one of the main use cases I had for this chromebook, and no one had bothered to reply to this thread, I have now arranged a refund for the chromebook through Amazon and will be sending it back to them sometime during this week, replacing it with a second hand Surface Book because I know that I can chromecast VLC videos from a Windows PC onto either of the TVs in this house without any issue, so that's really what I should have just done to begin with.
Anyway as part of #3, and since you've suggested it, I will be resetting the chromebook to factory defaults, so I'll give casting the desktop a try again after I've done that and update this thread so at least any other poor sucker that suffers this problem in the future might get some more guidance.