[Live-devel] Questions of bitrate

[Ross Finlayson]

>There are some situations where this is not the case. I do not know
>the exact technology behind it, but I think that material can be
>encoded for two (or more?) different resolutions, and at two (or
>more?) different bitrates. The reason I suspect this because I have
>heard about some small handheld devices that uses DVB-T, but does not
>decode the whole transport-stream to save power. This demands special
>encoding from the provider though, but is still standard compliant I
>belive, as i guess the ordinary receivers still would work.

Remember also that not all streaming uses MPEG Transport Streams, and 
not all streaming is from pre-encoded data :-)  When streaming from a 
live source (e.g., a camera), it may make sense for a receiving 
client to send feedback to the server (camera+encoder+streamer), to 
request that it reencode/restream at a lower bitrate - especially 
when using codecs that are scalable.

As I noted in my previous message, the RTP/AVPF profile (as defined 
in RFC 4585) supports such feedback (using RTCP).  I don't know how 
widely used this is yet, but it would be nice to support (for both 
clients and servers) in the "LIVE555 Streaming Media" code at some 
point.  (This of this as being another addition to the (already very 
long) wishlist...)
-- 

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