Well, I'm glad I had an excuse to play around with Quartz Composer; I
knew about it but had never spent any time with it, very cool!
Unfortunately, it doesn't solve my immediate problem. As far as I
can tell, compositions won't play streaming video at all. They work
great with movies from files, and with local live sources (iSight,
DV). But giving the "Image With Movie" patch an .sdp file just
results in a static QuickTime logo, it never shows any actual video.
Now I have at least three different methods for adding overlays to
pre-recorded video, but none of those seem able to deal with RTSP/RTP
streaming video. I'm going out on a limb here and conclude this
isn't just one or the other of the APIs having an issue, rather it is
a fundamental limitation in QuickTime, which can't (or won't) break
out individual frames for compositing when it is playing streaming
video. There are still things I haven't tried (i.e. Core Animation),
but unfortunately I'm out of time to spend on this. I have a stop-
gap solution in the separate overlay window approach, which works on
anything, the drawback being a lousy frame rate if the overlay is in
motion. But it is better than nothing, and I can have my app use
that only when it is playing streaming video, switching to one of the
better methods for other sources.
Thanks very much to everyone for the suggestions and help!
Bob
On Apr 24, 2008, at 6:34 PM, douglas a. welton wrote:
Bob,
Scott took the words right out of my keyboard... ;^} Have you taken
a look at the QCTV sample code? It does almost exactly what you want.
regards,
douglas
On Apr 24, 2008, at 9:16 PM, Scott Anguish wrote:
On Apr 24, 2008, at 9:05 PM, Bob Smith wrote:
In my case all I want to do is be able to add a scrolling text
overlay to whatever video is being played. My app is an
informational video kiosk display driver, it's meant to run
mostly unattended from playlists of images and pre-recorded
video, but with occasional scheduled live segments from
streaming video cameras on the local network. I'll take a look
at Core Animation, however one of my limitations is the app has
to run under Tiger, and I thought most of the CA stuff was new
to Leopard.
Would using Quartz Composer directly be an option for your app?
I don't know about the performance issues, but overlaying text on
top of video should be easy this way.
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