mpv cannot display the video bitrate in the OSC if there is only one keyframe in the file.

Important Information

• mpv version: shinchiro 20230701 0bfafd2
• Platform and Version: Windows 11 22621.1928
• Source of the mpv binary: shinchiro

Reproduction steps

Play the first provided sample file and bring up the info page. Compare to the second video.

Expected behavior

The video bitrate should be displayed.

Actual behavior

The audio bitrate is displayed, but the video bitrate is never displayed until the second keyframe in the video appears. In the second sample video that's about 5 seconds in. In cases where there is only one keyframe in the entire file (as with the first video) this leads to the bitrate never being displayed, ever.
The video bitrate can be inferred from the size of the 1 sec readahead cache, so that might be an entry vector for a fix. Or it may be changed to work how the audio bitrate works where it doesn't care about keyframes, although I'm sure that would have performance implications.

Log file

Broken: https://pomf2.lain.la/f/ktmk3ih7.txt
Working: https://pomf2.lain.la/f/mampr60a.txt

Sample files

Broken: https://pomf2.lain.la/f/jfk7pinl.webm
Working: https://pomf2.lain.la/f/k1fahjqe.webm

Start with mpv's OSC info page and compare the provided broken and working sample files and logs, focusing on when the video bitrate becomes available. Done means the video bitrate is displayed for the first sample without waiting for a second keyframe, while the existing working case remains correct.