Commit f8546d1f authored by Wim Taymans's avatar Wim Taymans

Some notes about pad disconnect

Original commit message from CVS:
Some notes about pad disconnect
parent 8d1e6c52
......@@ -398,7 +398,7 @@ NOTES:
- We probably need to set a limit on the maximum number of
recursions and size of the bufpen list.
- elements run non-preemtively, a group is done scheduling when all
- elements run non-preemptively, a group is done scheduling when all
elements in that group complete their chain/loop function.
- can we only have a stack overflow when there is a loop in the
......@@ -424,12 +424,60 @@ NOTES:
The time it takes for the first buffer to arrive at osssink equals
the time needed to decode the N-1 other buffers.
Of course, given the right buffersize for filesrc N can be reduced
Of course, given the right buffersize for filesrc, N can be reduced
to 1. mad can also suggest a buffersize to filesrc with the
BUFFER_SIZE event.
Ungrouping
----------
Ungrouping might be the hardest part. especially in the case where
an element is still running (state changes and pipeline modifications
in element callbacks).
Ungrouping involves two tasks:
- breaking up groups. This can happen when a pad connection is broken
so that the group contains two clusters of unconnected elements.
- breaking up chains. This happens when a pad connection is broken
so that the chains contains two clusters of unconnected groups.
case1
-----
The most simple case is where two elements are disconnected and one
of the elements does not belong to a group. In this case, we don't need
to do anything at all.
case2
-----
if the elements are part of different groups, we need to check if the
chain needs to be broken. A chain is broken if it contains two sets
of unconnected groups.
To test this case, we will create a new chain and recursively move
one of the groups with all of its connected groups to it. If the
origial chain is empty after this operation, there was still a connection
and the new chain replaces the old one, else we end up with two chains.
case3
-----
When the elements are part of the same group we check if both elements
still have a connection to some other element in that group. The elements
without connections are removed from the group.
It is possible that when an element still has a connection with some other
element in the group, the group has to be split up anyway. This can happen
in fakesrc ! indentity ! identity ! fakesink when we break the connection
between the two identity elements. We have to be careful here in the cothread
case that we don't take away the running cothread from under the elements.
In the non-cothread case we can just move the elements to another new group.
......
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