[Ffmpeg-devel] Adaptive Streaming???

[Ravi Chandra Nallan]

Does that mean that the media files have to be encoded at different rates and stored at the server?
Is there any chance of re-encoding on the fly, I mean can I encode each of the packets that I am going to send at a different rate. I know this would be very time taking for the server, but I would like to know if it is possible. There would lot of information loss in encoding packets separately than encoding the whole file, but can it be done?

If the server has to just pick up the right rate stream and pass to client, why does the Video On demand systems need high infrastructure. Coz most of this would be offline task of encoding media into different rates.

My questions may seem silly, but I am trying to understand what needs to be done for an effective VoD setup.
Thanks,
-Ravi

-----Original Message-----
From: ffmpeg-devel-bounces at mplayerhq.hu [mailto:ffmpeg-devel-bounces at mplayerhq.hu] On Behalf Of Fran?ois Revol
Sent: Friday, July 29, 2005 2:28 PM
To: FFMpeg development discussions and patches
Subject: Re: [Ffmpeg-devel] Adaptive Streaming???

> Hi,
> I need some knowledge on what comprises of Adaptive Streaming.
> I have been hearing this for quite some time, especially in the
> context of
> network bandwidth adaptation.
> I wanted to know if the file would be re-encoded to a different bit
> rate for
> network adaptation or a portion of it.
> coz, if the whole whole is encoded, as for the network congestion,
> the next
> stream of packets may need to be encoded in a different rate, hence
> the
> original encoding may not be useful.

Starting from the real "surestream" thingy, afaik the basic way of
things is:
the source is always encoded at multiple bitrate, and the player asks
whichever bitrate it wants depending on the congestion it detected
recently.
The change probably happens only on keyframes though.
The source must always be encoded at all bitrates, since not all
players might want the same bitrate at the same time anyway.
For static files, they just have several video (and maybe audio)
streams, and are hinted for the server. Like quicktime but others
including asf do this as well.

Fran?ois.

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