Resolves: https://github.com/untangledco/streaming/issues/41

The rest are initialised to zero values so we don't have to do it ourselves.

There was probably a bug here. Anyway it's less code!

No need to annotate the error; caller knows we're unmarshalling.

Consistent with the rest of playlist fields. While here delete duplicate Map writing function

fmt.Stringer is not really meant for larger multi-line text. It sucks a bit that we may return an error, but this lets us put some validation logic in; we don't have any validation yet.

Clearer than keeping most of the code indented

Return early with guard statements

Couple of problems. First we were unnecessarily masking bits. Secondly we were toggling the wrong bits in the final byte of an encoded audio channel in an AudioDescriptor. Resolves: https://github.com/untangledco/streaming/issues/39

Everything else are essentially guard statements

The layout is meant to be used internally; the external interface is regular time.Time values.

It's a bit of a hack that we read one item too many from the lexer. This change modifies segment parsing by sending the already consumed lexer items and subsequent lexer items back through another channel. Maintaining the original order through a channel means we can parse a segment in a single loop. Much shorter than dealing with the first item and all other items separately. This puts off looking into any redesigns of the lexer. For now...?

So we all know where it comes from if we want to get more.

Tests fail, but at least we have exposed the bugs

Playlist from https://test-streams.mux.dev/dai-discontinuity-deltatre/manifest.m3u8 containing discontinuities exposed the bugs.

We weren't really testing whether variants we parse from a playlist were what we expect. References: https://github.com/untangledco/streaming/issues/34

We don't necessarily need to make it easier to specify Variant test cases, we can pick the already easy-to-test bits of Variant to make better. References: https://github.com/untangledco/streaming/issues/34

The idea was to have a little playground using the packages we developed. But it didn't really turn out to be useful.