[Live-devel] Re:Re: Problem about on-demand unicast live streaming m4v

[Ross Finlayson]

>I provide the file here and hope it helpful:
>http://www.tanmax.com.tw/upload/test.m4v

Your file is a valid MPEG-4 video Elementary Stream; however, in this file, 
Visual Object Sequence Headers (i.e., beginning with 0x000001B0) occur 
infrequently.  There is one at the very start of the file, but the next one 
does not occur until several seconds later.

This causes a problem when the file is read from 'stdin'.  The reason for 
this is that - before it can begin streaming data - the server needs to 
read a "Visual Object Sequence Header" from the input stream, so it can use 
this header for the stream's SDP description (in the "a=fmtp: ... config=" 
line).  And after this, the server looks for a "Visual Object Sequence 
Header" once again, to form the start of the stream.  If the server is 
reading from a file, then it can do this by reopening the file.  If, 
however, the server is reading from 'stdin', then it can't 'rewind'; 
instead, it has to keep reading until it sees the next "Visual Object 
Sequence Header".  (In this respect, I was incorrect earlier when I said 
that reading from 'stdin' was identical to reading from a file.)

The solution to your problem is to reconfigure your MPEG-4 encoder so that 
it inserts Visual Object Sequence Headers more frequently - e.g., once per 
second.  If you do this, then lose no more than the first two seconds of 
the input stream.


	Ross Finlayson
	LIVE.COM
	<http://www.live.com/>