[Live-devel] Get one frame at an absolute time

[Ross Finlayson]

> I want to be able to request one single frame at an absolute time from the RTSP Client. Is that possible?

The RTSP protocol specification has an optional mechanism that allows this: specifying a range that uses SMPTE-format times (that can address individual frames, by number).  However, the "LIVE555 Streaming Media" code does not support this, and it is unlikely to be added in the future (at least, not for free).


> In the server end, my own OnDemandServerMediaSubsession implements seekStreamSource and I pass absStart/absEnd to my own FramedSource.
> 
> How should I implement my FramedSource doGetNextFrame so it only sends frames until the absEnd is reached (in this case only one frame).

That's up to you to decide.  However, if your underlying data source uses a "ByteStreamFileSource" object, then note that the "ByteStreamFileSource ::seekToByteAbsolute()" function has an optional parameter "numBytesToStream".  If this parameter is non-zero, then our implementation of "ByteStreamFileSource" will automatically limit the stream to deliver that many bytes only, before treating it as EOF.  So, if you can figure out how many bytes you want to deliver, and are using a "ByteStreamFileSource", you can do it that way.


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

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