[Live-devel] OnDemandRTSPServer working with File as File source but not File as Pipe

[Ross Finlayson]

> Both File as File and File as Pipe look great on VLC over the lan.  But to the iPad, the File as File looks great but the File as Pipe is very blocky, as if compression info is missing or whatever.
> 
> This tells me two things:  (#1) it seems VLC may be more robust and forgiving than our iPad app, as expected; and (#2) there's some difference in what Live555 sends (perhaps presentation time?) depending on whether the stream came from File as File or File as Pipe.

No, the difference is not the frames' presentation times, because they are derived from the input H.264 data, which should be the same in both cases.

The difference is likely that reads from the pipe - and thus transmissions over the network - are not happening smoothly.  I.e., you are probably reading a large chunk of data from the pipe, then waiting a long time (for more data to become available in the pipe), then reading a large chunk of data from the pipe, etc.  Because of these 'bursty' reads from the pipe, network transmission (of RTP packets) is also happening in a 'bursty' fashion.

Your receiving application *should* be able to handle this OK, if it does reasonable buffering of incoming data (i.e., data that has just been read from the "RTPSource" object).  But the fact that it's not handling this OK (but VLC does) suggests that your receiving player (on the iPad) is not buffering incoming data enough before decoding/rendering it.  That is the first thing that you should fix (because bursty/jittery data can happen in many environments).

However, you should also fix whatever is causing reads from your pipe (i.e., on your server) to be so bursty.  Because I don't know anything about your server OS, I can't help you here.  But if you are running Windows (which often has a notoriously coarse process-switching granularity), then please stop.  In this day and age, Windows is simply not a serious OS for running server applications.

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

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