[Live-devel] Questions of bitrate

[Morgan Tørvolt]

On 22/02/07, xcsmith at rockwellcollins.com <xcsmith at rockwellcollins.com> wrote:
>
> >> But I wonder can I reduce or increase the bitrate by controlling the
> server?
>
> I thought that the bitrate for a presentation was fixed by the recording?
> I have an encoder which can create a TS stream (MPEG2 data) at 5 Mbps or 4
> Mbps for me to record, but the quality is different between the two
> streams.  If am streaming a recorded presentation later and i tell the
> server to change the bitrate, but the recording was a 5 Mbps stream,
> wouldn't that have wierd results?

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.

A small screen like that does not need all the information to show a
decent picture anyway. I guess they use the same technology as
progressive JPEG, where a picture gets better and better the more data
you download. If there is a way to tag the TS packets with what
quality they are ment for, one could actually just grab the data that
one need, making it possible to lower quality and bandwidth and
possibly resolution and framerate on demand.

I have noe firm information to base this on unfortunately, but i did
find this information with a very quick google search:
http://forum.doom9.org/archive/index.php/t-98849.html

-Morgan-