[FFmpeg-cvslog] In retry_transfer_wrapper, do not check url_interrupt_cb,

[Martin Storsjö]

On Sun, 6 Mar 2011, Michael Niedermayer wrote:

> On Sun, Mar 06, 2011 at 11:48:22AM +0100, Nicolas George wrote:
> > Le sextidi 16 vent?se, an CCXIX, Michael Niedermayer a ?crit?:
> > > a 2 or 3 level abort should be used. Like unix TERM & KILL
> > 
> > It is an interesting solution, but is it necessary?
> > 
> > With the check for url_interrupt_cb at the end of the loop, the code works,
> > just as it has worked for a long time. It just needs a little clarification
> > in the documentation.
> > 
> > Adding this multi-level interrupt system would not solve any problem
> > currently known. And when a problem will actually arise, we do not know
> > whether this will be enough to solve it.
> > 
> > Designing a solution without a problem is rarely a good idea.
> > 
> > For now, I think it would be best to just restore the check of
> > url_interrupt_cb at the end of the loop and document that url_interrupt_cb
> > makes the protocol it has interrupted unusable.
> 
> we cannot make the writing protocol unuseable as a first level meassure to quit
> 
> when q is pressed we need to write, trailer + index + seek back to begin +
> update filesize and frame number in header for some formats.
> when q is pressed we didnt even yet start writing the index and trailer
> 
> multiple levels are the obvious solution.
> level 1, simply stop in the user app cleanly (this needs no call back value)
> level 2, hard abort any reading protocols returning incomplete data if needed
> level 3, hard abort any writing protocols this will cause inconsistence between
>          what is written and what the muxer wanted to write. Depending on file
>          this may render the file unplayable or some frames at the end missing

Yes, I think something like this would be useful. A simple first step 
would be without a distinction between level 2 and 3, only interpreting 
the first 'q'/ctrl+c as a graceful "please don't transcode any more data, 
start writing the trailer now", and only triggering url_interrupt_cb() on 
the second one.

// Martin