The per-stream variant_bitrate is not a reliable selection key. FFmpeg
attributes the whole variant's bandwidth to individual streams, and for
streams shared by multiple variants the value was bogus or missing
depending on the number of variants sharing the stream. The program
metadata always carries the exact HLS variant BANDWIDTH, so use it as
the only key and drop the per-stream fallback.
Note that with `--flatten-editions` tracks are selected by their own
tags, so they may still use bogus values.
For context, there is currently a bug in lavf where, depending on the
number of variants sharing a stream, the stream may or may not get
`variant_bitrate`. This will be fixed in a future FFmpeg release.
Kacper Michajłow
e7191f2a65