[BUG] Removal of "Simulated Live" breaks VOD transcoding

[SoraBytes]

I use to enable "Simulated Live" checkbox because it made "Stream Processes" actually work on VOD content, but now that its been removed (Wasn't ment to be available?) all of my VOD playback fails now.

I'm using "MP4" (AAC, H264) recorded from OBS via RTMP with an automatic push to a file saved in a "VOD Folder" served via mistserver for playback. Accessing that file works with "vod+sora.mp4.mp4" but because the "Simulated Live" is no longer toggable all transcoding fails.. e.g. "vod+sora.mp4.jpg", "vod+sora.mp4.mp3" or "vod+sora.mp4.webm" are unplayable.

Is this intended? Was I using this feature in a way that wasn't intended (e.g. Should be serving multiple files instead?)

[Thulinma]

Oh wow - I had no idea anyone had a working configuration with that flag manually enabled. 👀 Interesting!
Normally, correct functioning of the simulated live mode requires some very precise setup, which is done by MistInPlaylist. You can still use the functionality as you were by creating a .pls extension text file and writing the filename of your media (either relative or absolute path) as a single line as the contents of that file.

While doing this indeed allows on-the-fly transcoding, it's missing a few important things:

• There is no cache, so every playback attempt more than ~15s after the previous will re-transcode the media
• There is no tracking of playback position, so a second viewer joining some time later will not be able to receive the "missed" transcoded media and start playback part way into the file

We're actually working on improvements to our VoD support, including support for a "generated media" cache (where you'll be allowed to set a max cache size and the oldest data is thrown away to make room for new data, and then re-generated if it was removed from the cache on next access) and the ability to associate "derivative files" with an "original file" (for lack of better terms) so that the system knows these represent different codecs/qualities/versions of the original. This system could also generate the "alternate" versions in advance, rather than just-in-time (though that will also be an option, of course) for a smoother user experience.

That said: we currently have no clear ETA on that functionality being ready. In the meanwhile, you can simply revert the changes in input.cpp that were made in commit aa61d1a and things should work as they did in the past again.

Finally: if you have the time to talk about it, I would love to hear more about what you're using MistServer for - it sounds like a use case we're not very familiar with and learning more about the "why" behind your setup would help us keep that usage in mind for the future as well! 👍

[SoraBytes]

Thanks for this information, and the commit I'll revert input.cpp to the listed commit to restore functionality. I would be glad to explain my setup and use case (its personal stuff mostly), If I dont provide information you need/want (or make it confusing) let me know!

I recently started hosting from home, so my setup is a bit "complicated" if you go beyond the mistserver/webserver setup, atleast for networking due to firewalls and VPN usage with custom ACL's and restrictions.. The reason I'm doing what I'm doing is mistserver is a free and its webui is amazing with good ACL restrictions via triggers for live streaming, or video playback access so I can limit who can view, access, and I have created a "custom" website (PHP) that allows you to see who is live (akin to twitch) but for more "personalized for friends" type stuff (More similiar I would think to "owncast" project, but supporting multiple streams)

But the reason VOD is important with actual live transcoding for me is because I play a lot of games, and some of my games feature "media players" or "live radios" ingame either via libVLC, or CEF, or some other manner. If i download a video with yt-dlp (or stream via OBS for "gameplay" recordings) some game(s) dont support "mp4" or "webm" or "ogg" or "mp3" or various other media types for playback due to licensing restrictions, or aging media playback, but with the live transcoding (VOD's "Simluated Live") I can serve any type of media "ingame" that it might want and keep it synced between clients roughly so they all watch/listen at the same time ( like twitch, but in most circumstances they cannot skip around with the ingame media player so its not much of a concern I just want to sync it so we can all watch/listen together ) while also making any format possibly needed accessible on the fly on the off chance a particular game doesn't support a specific format..

Generally this is a setup for mainly my family to listen to real music, or videos together in games, and not publicly accessible.

Garry's Mod for example, with out the "CEF" patch by the community (which we dont want to install) cannot play a vast majority of content but using the live transcoding for live streams and VOD ("Simulated Live"), anything could be served that would normally fail for regular playback due to lacking proper "CEF" patch fixes for multimedia codecs.

Unfortunately I deleted my Arma 3 youtube video I recorded showing off "live" radio playback via Arma 3's radio plugin using mistserver's VOD ("Simulated Live") functionality via ".mp3" format that served actual music in a endless web radio to clients but also was accessilbe with ".mp4", ".aac", ".ogg" and ".wav" to support other games..

Another game this would be viable for is "American Truck Simulator" or "Euro Truck Simulator 2" both of which support "live" ingame radios, and I can have a single media server processing all the music and control it litterally ingame. (lower/higher volume, on/off)

[SoraBytes]

Another reason for live encoding for me with VOD content, is I have more than enough GPU/CPU power, but not a lot of storage to make duplicates (Despite a 1TB NVME for the server. Most of it is consumed by game servers and other data)

[Thulinma]

Thanks, that makes sense! What kind of formats do you find yourself converting from/to, to get the compatibility you want/need? (At least I assume some combinations are more common than others.)

[SoraBytes]

Generally, so far I end up using the following as the most common depending on the games that I live transcode to.

These are not listed in any particular order, but I tried to place them in how I often check against them in games.

1. MP4 (hit or miss due to licensing, or availablity)
2. AAC (above, but if MP4 works and I dont need video)
3. WebM/VP9 (usually accepted with Chromium Embedded Framework in game, or newer games)
4. OGG (If WebM/VP9 works and dont need video)
5. MP3 (generally accepted and used if i need audio only)
6. WAV (generally accepted and used if I need audio only).

In general I try to keep a single copy of a file on the server (no duplicates to save space) I often will convert my own media to "aac" for audio only, or "mp4" for videos and from that have mistserver transcode to whatever format I need. Alternatively if I pull say a youtube video with yt-dlp to play in games that youtube support is broken but allows links it usually pulls "mp4" or "webm" and it transcodes from that to the above formats as needed.

You can still use the functionality as you were by creating a .pls extension text file and writing the filename of your media (either relative or absolute path) as a single line as the contents of that file.

I tried this with for f in *.aac; do echo "$PWD/$f" >> playlist.pls; done when accessing the stream it took forever to load and was spamming something about "invalid track index 0" and wouldn't play any of the media except the first one after like full minute of waiting, skipping through it or the song ending just reset to the first one. I can create an issue for that if you'd like. Probably user error I didn't spend a lot of time testing it.

[SoraBytes]

I would also like to point out that I use the "folder" method for VOD not any single files or playlists, so media is directly accessible as needed via wildcard streams. This makes it easier to pull what I need in any format and also works with VOD recording of gameplay streams with OBS via AUTO PUSH to a file in the VOD folder. Not sure if this would matter currently but pointing it out for the future VOD system