[rtmpdump] Experimental patch to automatically disable BUFX

[Gunnar]

Thanks, not yet time to check your patches, but some quick observations 
I made in regards to the CSPAN server and stream.

EOF good as trigger, 20k mastodont packets 2.75s apart, keyframes?, 
stream feed always returns, jumps "backwards" to earlier, latest one.
---
Triggered debugging using the EOF ctrl message from CSPAN, seemed to 
work very well
I checked with wiresshark too, easy to search for "pause", found in 
notify and unpause,etc as ASCII

Checked actual last timestamp before the EOF and the ones used by 
rtmpdump to restart stream, and first arrived after restart.
Some odd behavior, but then noticed the restarted feed continues, or 
"backwards-jumps" to "nice decimal numbers".
Additionally a nearby 'mastodont packet" (npacketlenght? somewhere in 
rtmp.c).
OK set a print-test for more than 10K, looked good, then 20k, PERFECT!! 
Catches only these 2.75s packets.

FInal observation-result.

- Not sure, not dble-chked, but CSPAN-server seems to want 5.5s buffer
- every 2.75s, a "huge mastodont rtmp-packet" (have not digged deeper, 
video keyframe probably??)
- Most important, after the restart of the stream the feed always starts 
from the earlier latest "20k mastodont packet"

That is, typical behavior

- CSPAN server does notify/pause, EOF at some random point (obv after a 
20k-packet)
- after BUFX-restart the stream-feed starts from the earliest "already 
streamed" 20k-packet (keyframe?)

Nice timestamps like in your log,the 1800,000 + 6ms

1807985 ms to 1800006 ms"

when  accounting for  the "small milliseconds", 6ms, closest timestamp 
to that exact N x 2.750s

PS Additional observation, I am getting these EOFs appr every 4-8th 
2.75s (mastodont packet).
Maybe 2.75s or 5.5s also is some kind of  quarter or half buffering 
size?? Wld make sense togther with keyframe interval,

This when streaming speed was appr 300kB/s, compared to nominal, hmm.. 
60-80kB/s?
(with some CSPAN servers and sometimes, I actually get upto 800kB/s 
although"far away")


Gunnar