[Live-devel] Totally flummoxed about video quality, myDeviceSource->myOnDemandRTSPServer

[temp2010 at forren.org]

To Ross, I assume...  You're so insightful and you always seem to nail it
on the head.  Perhaps you can give me some guidance here again.

I got my named-pipe (actually I think it was an anonymous pipe) on Windows
working with good quality, from my video source software, through Live555,
and out to either VLC or custom iPad app.

But the pipe latency was over one second.  Far too long.  So I'm back to my
prior attempt that used myDeviceSource (MF_H264_DeviceSource in prior
emails) based solution.

Back on the pipe, I had similar bad quality.  It turned out to be mostly
due to the horsepower and speed with which I pushed into the pipe, as well
as the amount of memory given to the pipe (whatever that actually
controlled).  I discovered this by noticing VLC message logs about frames
being late by 100, 200, even 400ms.  Along the way, I put trace statements
into your Live555 code so that I could understand what's happening.
 Presentation time seemed important, although I recall you saying once it
wasn't so important.  But presentation time changes related directy to the
VLC late messages, and when I got rid of the VLC late messages, good
quality came through.

So now back on myDeviceSource, I've tweaked some presentation time stuff
and the VLC late messages have gone away.  In essence, just like is done by
ByteStreamFileSource and even H264VideoStreamFramer, the presentation time
is set once in the beginning, and then only ever incremented (25fps=40ms)
after that.  But even though VLC no longer complains about late frames, the
quality is still horrible.

I temporarily added a trace to H264VideoStreamParser to report both the
presentation time and the current time.  On the trace output, this helps me
tell not only what the presentation times are, but also if I'm feeding into
the parser (indirectly through myDeviceSource) frames at a high enough
speed.  It seems that I am.  So this should not be a case of not sending
fast enough, as was previously the case (on a different computer remote
from me) for the pipe.

I have no clue what to try or what to do or what day it is.  HELP!

(BTW, I tried to look up the specs for H.264.  I found a cryptic 500+ page
pdf.  That's just too overwhelming to even start.  I'm smart and I know
allot, but I don't know this already and can't afford the years it would
take to really understand it... like you do!)

Thanks...
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