Data.MediaBus.Media.SyncStream

A module for removing and creating sequence numbers and time stamps for Streams.

It's sometimes helpful to explicity use a SyncStream instead of a Stream.

For example, for a library function that consumes Frames and doesn't regard the sequence numbers and time stamps, such that the function does not handle any gaps and/or out of order packages or discrepancies in the time stamps and frame durations.

When the library author chooses SyncStream, the library users then know, that the library function relies on a synchronized stream.

Documentation

type SyncStream i p c = Stream i () () p c

A Stream without sequence numbers and time stamps is called a SyncStream, which is the abbreviation of synchronous stream, because when the sequence numbers and time stamps of a Stream, and by extension of a Frame and FrameCtx, are always (), the Frames of a Stream can be assumed to be (perfectly) synchronous.

assumeSynchronized :: Stream i s t p c -> SyncStream i p c

Convert a Stream to a SyncStream by simply forgetting the sequence numbers and timestamps of the input. This expresses the assumption that the Frames are either perfectly lined sequential or that this doesn't matter at all.

setSequenceNumberAndTimestamp :: (Num s, CanBeTicks r t, HasDuration c) => SyncStream i p c -> (s, Ticks r t) -> (Stream i s (Ticks r t) p c, (s, Ticks r t))

Set sequence numbers and timestamps. Increment the sequence numbers starting from 0 for every frame. Start the timestamp at 0 and add the Frame duration of the Next frame in the stream. This function has the signature required to turn it into a State monad.