[PATCH 1/2] winegstreamer: Implement pausing the media source.

[Nikolay Sivov]

On 6/10/21 7:25 PM, Zebediah Figura (she/her) wrote:
> I agree with Derek's comment here. Assuming that buffering samples
> like this is the right thing to do, I also wonder:
>
> * should we buffer samples, or requests?
>
> * should the samples/requests be stored in a flat array instead of a
> linked list? Based on usage patterns it seems that'd be easier and
> more efficient.
>
Agreed, list vs array is not really important one. Why do we need to
buffer samples, is that to cover for discrepancy for already issued
requests before Pause() was called? And what should really happen there,
if we queue async command on RequestSample() (which is already
questionable) any number of times, and then call Pause(), or Stop(), we
should have a way to drop pending requests. And that's not possible with
MFPutWorkItem().

With this patch any Start() when paused results in draining all the
samples to the receiver, and that's not obviously correct, unless that
was somehow tested. I imagine if you seek to a new position in either
direction, you're not really interested in old samples. If session
currently does not handle this correctly (by resetting expected samples
counters, etc), we should figure out how to test it separately.

> -    unix_funcs->wg_parser_stream_seek(source->streams[0]->wg_stream, 1.0,
> -            position->hVal.QuadPart, 0, AM_SEEKING_AbsolutePositioning, AM_SEEKING_NoPositioning);
> +    if (position->vt != VT_EMPTY)
> +        unix_funcs->wg_parser_stream_seek(source->streams[0]->wg_stream, 1.0,
> +                position->hVal.QuadPart, 0, AM_SEEKING_AbsolutePositioning, AM_SEEKING_NoPositioning);
>      unix_funcs->wg_parser_end_flush(source->wg_parser);
Is this really relevant to Pause() ?

> @@ -318,6 +345,8 @@ static void start_pipeline(struct media_source *source, struct source_async_comm
>  
>              IMFMediaEventQueue_QueueEventParamVar(stream->event_queue,
>                  seek_message ? MEStreamSeeked : MEStreamStarted, &GUID_NULL, S_OK, position);
> +
> +            flush_pending_queue(stream, TRUE);
>          }
>      }
>  
This will send old samples before MESourceStarted/MESourceSeeked, which
is questionable.