New Encoding Format for Videos - HMV Mania

We’re utilizing a new encoding format for videos.

Recent Videos

You may have noticed a difference in the recent releases with the filenames containing av1 in them. First we’ll provide some background on what videos have been using up until recently, and what we’d like to do moving forward.

The mp4 standard the past 3 years

Ever since HMV Mania started, videos have been standardized to the following:
– 1280×720 or 1920×1080. Higher resolution videos (e.g. 2560×1440, 3840×2160) got downscaled to 1920×1080. Nonstandard resolutions e.g. 1440×1080 got letterboxed on the sides to be a standardized resolution.
– 24 FPS
– 3 MB/s bitrate
– H264

Back then in 2021, encoding formats like AV1 were still going through extensive developments. This site grew to a point where we have over 3,000 videos using this H264 mp4 standard. We also were considering HLS streaming although the cons outweighed the pros when we discussed it internally.

This mp4 standard did give us very consistent results over the past 3 years, although it came with its drawbacks:
– more noticeable compression given H264 is less efficient at retaining quality than other formats such as HEVC and AV1.
– significantly lowered framerate, especially for 60 FPS videos.
– not sticking to the original video’s resolution.
– some videos were not as efficiently encoded as they could be with an encoding like AV1, so in a lot of cases we missed space savings.

The AV1 encoding format

Since the original HLS streaming plans didn’t follow through, AV1 could be considered with keeping the current site architecture.

AV1 encoding allows for efficient compression savings while retaining most of the original video’s quality. Some people have been able to accomplish reducing a video’s filesize by over 90% while retaining 99% quality or higher, although that came with incredibly slow encoding times.

After some initial testing, we found a balance of the following three topics:
– encoding time
– retained quality
– filesize savings

We found that for 1080p videos at 30 FPS, we could save around 50% the space compared to the previous 3 MB/s standard and at a higher retained quality. Initial testing done had results around 97% based on VMAF score.

A big drawback here is that we don’t have a nice predictability of filesize and storage, since higher resolution videos with higher framerates give larger filesizes with AV1. It’s a tradeoff we’re willing to make, however.

Compatibility with devices

Based on analytics data, 55% of users on the site are using a mobile device. 41% are on desktop.

AV1 video encoding is supported on most modern browsers, although there are some caveats, especially with mobile devices. The site “caniuse” is a great reference to see what devices and browsers could play this format.

The backend dev’s iPhone was able to play the AV1 videos, although we had a user with an earlier iPhone version that was unable to play the videos. The limitation seems to be the following based on caniuse:

Supported only on devices with hardware decoder, e.g. iPhone 15 Pro, M3 MacBook Pro, etc.


Safari browser users may also experience similar behavior.

Forum Link in the sidebar

The sidebar now has a link to the forums, which there is planned to be more activity about AV1 video updates there. As of now, the following AV1 replacement efforts have taken place on the site:
– Aleksandr Synii
– hentaibrox274
– NTRfella
– xeohmv

We have a planned AV1 replacement for videos under Martoise in the works. In the meantime, there is an mkv download archive in this thread.