Cast: Limit number of events/packets in EncodingEventSubscriber protos.

media/cast/logging/encoding_event_subscriber.h

Index: media/cast/logging/encoding_event_subscriber.h
diff --git a/media/cast/logging/encoding_event_subscriber.h b/media/cast/logging/encoding_event_subscriber.h
index ba9969bd2c986e245a20a2e55829465db6e250f5..e4d19c76af3d5afc64f31dc66b0f91d5b6a6ec17 100644
--- a/media/cast/logging/encoding_event_subscriber.h
+++ b/media/cast/logging/encoding_event_subscriber.h
@@ -23,6 +23,15 @@ typedef std::map<RtpTimestamp,
                  linked_ptr<media::cast::proto::AggregatedPacketEvent> >
     PacketEventMap;
 
+// Number of packets per frame recorded by the subscriber.
+// Once the max number of packets has been reached, incoming events will be
+// discarded.
+const int kMaxPacketsPerFrame = 64;

[Alpha Left Google, 2014/04/17 22:59:00]

This number seems small. Why is this 64? Instead of dropping events can we log
with an extra protobuf?

[imcheng, 2014/04/18 00:05:31]

How often will we have more than 64 packets per frame? What number would you
suggest?

I would rather keep it simple and just pick a max number here.

[Alpha Left Google, 2014/04/21 18:14:04]

Sometimes this can happen. A scene change frame can be large (~100kb). Plus
retransmission there can be many more. 

[imcheng, 2014/04/22 01:17:39]

ACK.

On 2014/04/21 18:14:04, Alpha wrote:

+// Number of events per proto recorded by the subscriber.
+// Once the max number of events has been reached, incoming events will be
+// discarded.
+const int kMaxEventsPerProto = 16;

[Alpha Left Google, 2014/04/17 22:59:00]

Why is this 16? It seems small..

[imcheng, 2014/04/18 00:05:31]

How about 32? Normally a proto will rarely have more than 10 events. The only
events that would repeat are retransmission and rtcp events (to a limited
extent).

[Alpha Left Google, 2014/04/21 18:14:04]

I don't see much value in this limit. This limits the types of events in a proto
right? If the most common event type is packet event then having this value
isn't very useful I think.

[imcheng, 2014/04/22 01:17:39]

This limits the number of events, this helps keep individual protos down in
size, when there are a lot of retransmit events for the same packet.

On 2014/04/21 18:14:04, Alpha wrote:

+
 // A RawEventSubscriber implementation that subscribes to events,
 // encodes them in protocol buffer format, and aggregates them into a more
 // compact structure.