Adventures with OBS Studio and ffmpeg

Here are some of the adventures I’ve had whilst trying to record from the Sky Stream puck using OBS Studio and ffmpeg.

I have split my Sky Stream box into two HDMI outs – one goes to the main TV and the other is coupled with a Ugreen HDMI to USB converter or capture card.

What I’ve tried: OBS Studio

I began by testing OBS Studio. It works and it works very well…when it worked. The main issue with OBS is my input from the Ugreen capture card. It consistently fails to display the preview image, requiring a disconnect and reconnect of the Ugreen capture card, or a cycle of the EPID modes on the splitter. At other times, it needs the Sky Stream box to be restarted. This happens a lot and is a pain in the backside when one expects to simply plug-and-play.

I initially thought that this was the Sky Stream box playing tough but the issue is the same from my Formuler box. The audio passes through immediately but the video does not display in the preview for some reason. And, of course, that translates through to the recording: if trying to record where no preview is shown, no image.

The recording capability of OBS is fantastic, and I cannot fault it. The only issue for me is the lack of consistency when connecting my laptop to initiate a recording. OBS Studio therefore cannot be relied upon as my recording solution.

I might add here that my initial OBS package was a Flatpak. However, this preview issue persisted even when using the official build from the Ubuntu repositories. OBS Studio is nice to work with, but it does not gel with me and my hardware, and we have now parted company.

What else I tried: ffmpeg

Connecting up directly with ffmpeg works flawlessly. Because there is no preview, a quick check of the input stream (video) shows that ffmpeg does not behave the same as OBS.

ffplay -f v4l2 /dev/v4l/by-id/usb-Actions_Micro_UGREEN-25854_-1575465188-video-index0

Before recording, I run that to check the input. Once I see an image, I’m good to go. ffmpeg has not failed nearly as much as OBS to preview the image. When it does fail, it doesn’t require playing around with EPID modes; a simple off/on of the Sky Stream puck is enough to kick it into life. And that I can live with.

One good thing that OBS studio showed me was that I can now record without using libx264. OBS would happily record a 1080p stream with my CPU sitting on 3%.

My first attempt with ffmpeg led me down my familiar path of encoding with libx264. CPU was at 75% and the fans were screaming blue murder after 3 minutes. So, VAAPI it has to be, using AMD’s onboard GPU.

See, I’ve long been used to using libx264 all my life due to the quirks of GPU encoding I experienced in the past with both AMD and Intel chips. That, however, was a very long time ago and it appears that things have improved drastically on that front. Also, I’ve never attempted recording streams before; my usage was always on a re-encode basis. Intel of old was always superior but I have AMD now and it is just fine for my needs.

My initial recordings experienced a bit of “choppiness” in some scenes. I’ve put that down to CPU encoding or frame rate and have made many, many tweaks to the massive ffmpeg command I have settled on.

We’ll get to that.