Add pause/resume and auto resume to the offline API

[itaykinnrot]

Today if you try to download a big movie and stop in the middle - next time you'll need to restart the download since there isn't any logic that check what already downloaded.
The suggestion here is to check if the keys already stored and only fetch the missing ones.
In addition user may want to pause & resume download - add this API

[TheModMaker]

We'll consider it in the future. This will likely just have to be an explicit pause() and resume() methods, we may not be able to recover from a stopped download (e.g. by closing the tab). This is because it will be difficult or impossible to tell the difference between a download that stopped and one that is still going in another tab.

But we may be able to have an explicit pause method where we can store which pieces we have downloaded already. But this will be a low priority feature since we would need to store much more info in the database and we are already having troubles with different database versions.

Note that we can't just detect existing segments since: (a) we use unique keys so there will never be existing keys and (b) a segment that is the same as an existing one may be from another stream so we can't just reuse it. Currently we delete segments when we delete the manifest, so if we reused the segment, that segment would disappear when we deleted the other manifest.

Also note that if you stop a download using storage.destroy(), then we will delete any partially downloaded content, so there is no resuming.

[OrenMe]

Pause/resume of a download without closing the tab is indeed easy - already have a working POC with a checkPaused promise before calling download segment.
I think this is very narrow use case as clients would like a more rich experience.
Can you elaborate on the DB issues? Is this the only limitation as you currently see it? As I think it would be indeed mandatory to signal the download state between tabs via the DB with a manifest download state flag or some kind of signal.

[TheModMaker]

See #1248 for more info on DB issues. Basically we are having troubles with database versions and upgrades. We will need to make some major changes to the internals to allow for handling different database versions. Since this will require more changes to database structure including possible changes to the schema itself (e.g. maybe adding a new table for pending segments), I think this should wait for that issue to be closed.

[joeyparrish]

We will also need to consider how pause/resume interacts with background fetch in #879.

[odedhutzler]

Hey @joeyparrish, any updates here? Are you planning to add the new features?

[OrenMe]

Hi @joeyparrish @TheModMaker is there any update to pause/resume capabilities?

[OrenMe]

Hi, any update on this?

[joeyparrish]

Hi, any update on this?

We are not working on this internally at the moment.

Are you planning to add the new features?

Yes, Shaka Player development is still ongoing. We are still adding features and making releases.

[OrenMe]

thanks @joeyparrish, will you be open for us to work on it and contribute back? wouldn't want to start work on this without syncing with you first.

[joeyparrish]

@OrenMe, sure, that sounds good to me. We'd love to have a PR for this. Just give us an example of the API you're adding, so we can make sure it's in line with our own designs. Better to give you feedback on the API before you get all the way to a PR, so you don't waste time.