[vlc-devel] Re: How to parse MPEG-2 or MPEG-4 stream to get "layers"

Christophe Massiot massiot at via.ecp.fr
Tue Nov 2 01:15:13 CET 2004

At 19:06 -0500 1/11/04, Alvin Chin wrote:

>I know that MPEG-2 allows you to encode in layers using MPEG-2 
>scalability and MPEG-4 can encode layers using FGS, but I am 
>wondering how I can read that information so that I can just send 
>only those layers to the client.  In other words, create a 
>progressive streaming media video that just retrieves the base layer 
>and then the user can request enhancements of the video by getting 
>other layers.
>I am trying to read the source code and the API documentation, but I 
>am kind of lost as to where to read.  I think I have to parse the 
>MPEG header.  I know that the stream description can be viewed as a 
>tree but where can I access that tree?

VLC is an MP at HL MPEG-2 decoder. We do not support scalability. AFAIK 
no one supports MPEG-2 scalability. And I have never seen any file 
with a base layer and an enhancement layer. I have only seen it 
mentioned in ISO/IEC 13818-2 (you probably should get it from 

Good luck,

Christophe Massiot.

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