[rtmpdump] librtmp performance and high latency

[ctetrick at satx.rr.com]

Hi, 
I'm using a windows build of ffmpeg from zeranoe which uses librtmp.
There is a long standing problem that I'm trying to fix.

There is a case on the ffmpeg bug tracker: 
https://trac.ffmpeg.org/ticket/1604

And a related thread on the forum:
http://ffmpeg.zeranoe.com/forum/viewtopic.php?f=7&t=657&sid=276f96e2c4ff9f62a2733007f2e82e1c

I've posted on both.

The basic problem is that RTMP_SendPacket() writes to the socket in 128 byte chunks, and when the destination server has a long RTT the stream stalls.  I've tested with a simple fix - there is code there to buffer the chuncks for HTTP, but if the buffering is enabled for all sends, the whole packet is written to the socket, and the stream works much better.

I'd really like to get this or something like it into a patch. I think it may fix this problem.

Anybody have any feedback on this? 

Thanks, 
Cary