The origin in protection events is optional, the stream id in
stream-start events is not.

Also return a segment reference instead of a segment copy when parsing a
segment event.

It can contain no value.

Also use &ToSendValue instead of an actual value for building the
message.

Also ::copy_deep() can fail, return an Option<_>

The implementation for Option<_> is doing exactly what we did manually
here.

These are gst::ClockTime, not u64

There's a buffer() for immutable references on all types now, and a
buffer_mut() for getting a mutable reference on the writable videoframe

Also some minor other cleanup

Move the constructor of the builder to the main type

Various nullability, types and usability fixes. The player configuration
is a new type now that can deref to a structure

No need to map the buffer again, we can just compare the slice directly.

Replace AppSrcCallbacks/AppSinkCallbacks with a builder so that no empty closures have to be provided for unused callbacks

Philippe Normand authored Dec 10, 2017 and Sebastian Dröge committed Dec 10, 2017

In the previous generated player bindings the position-updated was Send+Sync but
only Send is actually needed. In addition to this change the position-updated,
duration-changed and seek-done signals now invoke their handler with a
gst::ClockTime value instead of u64.

Otherwise we conflict with GLib translation traits, which causes some
annoyances.

FormatValue is now renamed to GenericFormattedValue and the API slightly
changed. In addition there is now a FormattedValue trait, and a
SpecificFormattedValue trait plus types for Bytes, Buffers and the
existing ClockTime.

This allows to create functions like
  Pad::query_duration<F: SpecificFormattedValue>() -> Option<F>
and doesn't require the caller to unwrap the generic value anymore,
which is completely unneeded in these cases.

In addition, Segment became FormattedSegment<T> with API to
upcast/downcast between the specific formatted values and the generic
formatted value. This greatly simplifies usage of Segments.

This is guaranteed to be of the correct type.

We need to scale the number of samples, not the buffer size.

And implement the Value traits for ClockTime