Should we improve video quality?

[rgaudin]

I am not very satisfied with the video quality of the ZIM files we serve, especially given we provide a single flavour. AFAIK, we have not received any complain about it though (@Popolechien can you confirm) but it bugs me a little.

I also know that the current compression settings have been selected years ago so I was wondering if we should update it a bit, at the expense of bigger ZIM files, of course.

I wrote a little script to test a couple other presets and compare the output with the current encoding.

You can see the result in report.html. I am attaching a screenshot in case this goes away…

As you can see, I randomly selected sample videos from the channels we scrape and compressed all of them with 3 different presets:

• previous: the one we currently use in the scraper. HVGA resolution (480x270) with very aggressive quality range (30-42) and a 300k bitrate average (but with a weird 1000k bufsize).
• 240p: 240p resolution (426x240) with good quality range (16-26) but a constant video bitrate of 128k and audio bitrate of 48k.
• 360p: 360p resolution (640x360), similar to 240p but with 384k bitrate.

Unfortunately, the 240p while reasonably bigger than previous is not significantly better. It works best on animations and texts, but otherwise barely noticeable.

The 360p is way better but also way bigger.

I though it could easily demonstrate better quality without major size impact but could not. Still, we may want to tweak the converter in the future and I think that script is a good way to try and compare.

@kelson42 should I push it here in a contrib folder or should it be pushed somewhere else?

[kelson42]

@rgaudin Yes, please put the tool in contrib. This is a valuable script.

[rgaudin]

Script has been pushed ; @Popolechien any feedback from youtube users?

[Popolechien]

Only this one (from a Hotspot user): "Ted talks - not the most user friendly landing page (thumbnails are stretched, just having a long scroll list is not the most easy visual to browse videos, making some basic categorisations here would be good). It's good that you can scroll for different languages but I had issues making the page update with my language selection."