<div dir="ltr">Hi Ross,<br><br>
<i>" To avoid this, use unicast streaming, using "testOnDemandRTSPServer", or "live555MediaServer". </i>"<br><br>please can you explain us how different is <i>"testOnDemandRTSPServer", or "live555MediaServer" </i>with <i>testMPEG4VideoStreamer </i>in using to reduce or avoid green screen. <br>
<br>I have given below the reason for this green screen and i think it cannot be avoided. If i am wrong let know.<br><br>It has so happen that session with server has started after Key
frame (I-frame) is sent & he as missed it . When the session
starts it will be downloading only p-frame without Key-frames in
which case there is No reference frame for these P-frame to do motion
compensation and this green screen is nothing but motion estimation.
You can reduce this green screen period by reducing the GOV(group of
videos) or GOP (group of picture) size at the server side in camera
settings. <br><br>P.S : GOP or GOV - Number of P-frames between 2 consecutive I-frames(Key frames).<br><br>with regards<br>shiv<br><br><br><br><br><div class="gmail_quote">On Fri, Aug 15, 2008 at 11:51 AM, Ross Finlayson <span dir="ltr"><<a href="mailto:finlayson@live555.com">finlayson@live555.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div class="Ih2E3d"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
While receiving and playing back MPEG4 encoded streams using VLC, the first few frames happen to be green screen. The message window shows the following error<br>
"ffmpeg warning: warning: first frame is no keyframe". The playback gets back to normal state on the arrival on next MPEG4 keyframe. I observed this with testMPEG4VideoStreamer.exe. and the issue is consistent with repeated runs.<br>
Is it because client didn't get first few frames on MPEG4 stream?<br>
</blockquote>
<br></div>
Yes, probably.<div class="Ih2E3d"><br>
<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
where do the frames gets dropped?<br>
</blockquote>
<br></div>
Remember that "testMPEG4VideoStreamer" is a *multicast* application - it just sends the data to a multicast group, regardless of how many clients have subscribed to the group. Therefore, any data that it sends before the client runs (and subscribes to the group) will be lost.<br>
<br>
To avoid this, use unicast streaming, using "testOnDemandRTSPServer", or "live555MediaServer".<br><font color="#888888">
-- <br>
<br>
Ross Finlayson<br>
Live Networks, Inc.<br>
<a href="http://www.live555.com/" target="_blank">http://www.live555.com/</a></font><div><div></div><div class="Wj3C7c"><br>
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