[Live-devel] Ever-slowing frame-rate =(

[Chad Ata]

Hi Again,

so sorry to bump this post, but i'm really stuck on this!
To recap, I've written an MPEG DeviceSource, which I pass into an
MPEG1or2VideoStreamDiscreteFramer, which I'm broadcasting out to Darwin via
the DarwinInjector.

In my DeviceSource I'm setting the following in deliverFrame()
      fDurationInMicroseconds = 0;
      gettimeofday(&fPresentationTime, NULL);

VLC can receive (via rtsp) the stream fine (at full frame rate) despite
regular messages like: main warning: backward_pts != current_pts (400000)
QuickTime Player can also receive (via rtsp), but it eventually slows the
frame rate down to 2fps.

I've tried saving some of the MPEG frames my encoder is producing to a
file. The file plays fine locally (at full frame rate). So I tried to
stream the file via testMPEG1or2AudioVideoToDarwin and I got similar
results as with my application( the frame rate wasn't quite as bad in
QuickTime, but still way too slow). I tried the test program again with an
MPEG movie that I didn't make myself, and I had the same results.

I'm pretty sure my streaming server is fine as it can serve my other
streaming applications just fine.
Do you think this is a bug in testMPEG1or2AudioVideoToDarwin,
MPEG1or2VideoStreamDiscreteFramer, or MPEG1or2VideoRTPSink? or none of the
above? Is there anything I can do, perhaps in the sdp announce or maybe the
mpeg header, to notify QuickTime to just pay all of the frames it gets?

i'm totally stuck! anything will help =)
Thanks,
-Chad

-

                                                                           
             Chad Ata                                                      
             <Chad_Ata at brightc                                             
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             10/17/2007 11:17                                      Subject 
                                       Re: [Live-devel] Ever-slowing       
                                       frame-rate =(                       
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Hi Ross,

Thanks for the feedback.

I got a chance just now to test against VLC and I was able to get more
specific error messages:
.....
main warning: late picture skipped (677621)
main warning: backward_pts != current_pts (400000)
main warning: backward_pts != current_pts (-40000)
main warning: late picture skipped (97585)
main warning: backward_pts != current_pts (-280000)
main debug: decoded 42/108 pictures
main warning: backward_pts != current_pts (240000)
main warning: late picture skipped (285592)
.....

I'm relatively confident that I'm broadcasting the 25fps -- or at least
close to it. So I'm thinking that maybe my encoder is setting weird
presentation time stamps on the MPEG frames. whatever it is i think i'm
cursed =)

any more info would always be appreciated,
thanks !
-Chad





             Ross Finlayson
             <finlayson at live55
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             10/16/2007 22:07                                      Subject
                                       Re: [Live-devel] Ever-slowing
                                       frame-rate =(
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>I've tried setting fDurationInMicroseconds to 0 and fPresentationTime to
>gettimeofday(...), but that didn't help.

Because you're reading from a live source (which delivers frames in
'real time'), it should be OK for you to do this.  However, because
you're still seeing your problem when you do this, this suggests tat
the problem is that your source object is not generating/delivering
frames at the correct rate.
--

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/
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