Video playlists: Does it make sense to pre-convert?

[Moonbase59]

I’m using a video playlist for a webradio station. It has only a few (~10) videos which are in different formats, i.e. 1080p60, 1080p30, some even with 24000/1001 fps.

I’m outputting as ffmpeg 720p25 MPEG-TS, with AC3 sound.

In order to minimize CPU load on the radio station VM, does it make sense to pre-convert the source material into 720p25 format, or is Liquidsoap/ffmpeg fast enough that it doesn’t really matter?

If pre-converting, what format and container type would you suggest for optimal throughput with lowest CPU usage?

My output is currently:

output.icecast(%ffmpeg(format="mpegts",
  %audio(codec="ac3",channel_coupling=0),
  %video(codec="libx264",b="2600k",
         "x264-params"="scenecut=0:open_gop=0:min-keyint=150:keyint=150",
         preset="ultrafast")),
host="radio", port=8000, password="mysecretpassword", mount="/video.m2t", send_icy_metadata=true, public=false, s)

If all goes well, I plan to eventually add a HLS or DASH output to accomodate for various endpoint bandwidth requirements.

[Moonbase59]

Answering my own question, after watching closely what happens:

• No conversion seems necessary if the source material is max. 1080p, at a max. framerate of 30 fps.
• Pre-converting seems absolutely mandatory on 60 fps material, because LS simply can’t keep up when only minimal extra processing is required, like adding a logo, text or the like. LS will almost immediately start with "need to catch up" errors.

[gAlleb]

@Moonbase59 Hi! Figured out that maybe I could address to you here since no other means of communication are available)

I like how you're implementing your videostream. And I've noticed an interesting feature that you've added: the name of current playlist which is shown above the title. And I'd like to 'steal' it :) since i don't understand how to implement it myself. Would you be so kind to share the function/code of adding dynamic playlist name if it's ok? (Want to try it out with Azuracast)

Thanks!

[Moonbase59]

The code is still a mess (though it works stable for me since months). I plan to make it it available, either on GitHub or at least in a Gist, but let me clean some things up a little first, please. So many things to do, never enough time… Know how it is…

[gAlleb]

@Moonbase59 Sure thing.
Thank you! Looking forward!

[Moonbase59]

Just tag me if it tages too long, I’m just writing azuracast_xmltv, to generate EPG data from AzuraCast stations ;-)