[Live-devel] HD MPEG2 TrickPlay

[Ross Finlayson]

>Is there a way that the MPEG2 TrickPlay stream that is generated can 
>be generated in a way so that it will be streamed at the same 
>bitrate as in normal playback mode?

Note that - in the current implementation - the *average* bit rate of 
'trick play' streams is actually a bit *less* than that of normal 
playback mode, because 'trick play' streams stream only I-frames, 
which are a subset of the entire video data that's streamed in normal 
playback mode.  (E.g. in 6x fast-forward more, we stream every 6th 
I-frame, but nothing else, at 6x the normal rate.)

The problem, however, is that the current implementation transmits 
'trick mode' streams in a very bursty fashion, and this is apparently 
overwhelming the limited buffer space of some clients.  (Some people 
have reported the same problem with excessively VBR files even in 
normal playback mode.)

As previously dscussed on this mailing list, we have a solution in 
mind (it will require updating the index file format to include a new 
'duration' field, and implement a new Transport Stream 'framer' class 
that uses this).  There is currently no ETA for this, though.
-- 

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