[PATCH 0/1] MR1853: mf: Request more samples for MFT when needed.

[Shaun Ren (＠shaunren)]

When an upstream node has not given enough samples to the transform,
we need to request more samples from it to avoid stalling the
pipeline.

[PATCH 1/1] mf: Request more samples for MFT when needed.

[Shaun Ren]

From: Shaun Ren

When an upstream node has not given enough samples to the transform,
we need to request more samples from it to avoid stalling the
pipeline.
---
 dlls/mf/session.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/dlls/mf/session.c b/dlls/mf/session.c
index b2371763150..f8c00fbb4e7 100644
--- a/dlls/mf/session.c
+++ b/dlls/mf/session.c
@@ -3142,8 +3142,8 @@ static void session_deliver_sample_to_node(struct media_session *session, IMFTop
         IMFSample *sample)
 {
     struct sample *sample_entry, *sample_entry2;
-    DWORD stream_id, downstream_input;
-    IMFTopologyNode *downstream_node;
+    DWORD stream_id, downstream_input, upstream_output;
+    IMFTopologyNode *downstream_node, *upstream_node;
     struct topo_node *topo_node;
     MF_TOPOLOGY_TYPE node_type;
     BOOL drain = FALSE;
@@ -3213,7 +3213,15 @@ static void session_deliver_sample_to_node(struct media_session *session, IMFTop
                     WARN("Drain command failed for transform, hr %#lx.\n", hr);
             }

-            transform_node_pull_samples(session, topo_node);
+            hr = transform_node_pull_samples(session, topo_node);
+            if (hr == MF_E_TRANSFORM_NEED_MORE_INPUT && !drain)
+            {
+                if (SUCCEEDED(IMFTopologyNode_GetInput(node, input, &upstream_node, &upstream_output)))
+                {
+                    session_request_sample_from_node(session, upstream_node, upstream_output);
+                    IMFTopologyNode_Release(upstream_node);
+                }
+            }

/* Remaining unprocessed input has been discarded, now queue markers for every output. */
             if (drain)

[Nikolay Sivov (＠nsivov)]

Nikolay Sivov (@nsivov) commented about dlls/mf/session.c:
>                  WARN("Drain command failed for transform, hr %#lx.\n", hr);
>          }
>
> -
>        transform_node_pull_samples(session, topo_node);
> -
>        hr = transform_node_pull_samples(session, topo_node);
> -
>        if (hr == MF_E_TRANSFORM_NEED_MORE_INPUT && !drain)
> -
>        {
> -
>            if (SUCCEEDED(IMFTopologyNode_GetInput(node, input, &upstream_node, &upstream_output)))
> -
>            {
> -
>                session_request_sample_from_node(session, upstream_node, upstream_output);
> -
>                IMFTopologyNode_Release(upstream_node);
> -
>            }
> -
>        }

In general we don't really know which input branch to request from. That's why there is a fixme in session_request_sample_from_node() in similar logic. When ProcessOutput() returns need-more-input it means currently accumulated input samples across all inputs are not enough to produce any output. I suspect it could be caching per-input MF_E_NOTACCEPTING status, and trying to balance requests. Anyway, my point is that, I suspect, logic here should be the same as logic in session_request_sample_from_node(). Probably another helper would be in order.

Also, please add new request call under else branch of the following 'drain' check.