[theora-dev] Re: bitstream changes

Christian HJ Wiesner chris at wiesneronline.net
Tue Mar 18 14:09:32 PST 2003

Dan Miller wrote:
> ok now I see why we need another packet in the header.  The first one is basically for ID purposes (theora_decode_header()).  I've jammed my huffman trees in there but it sucks because I need them later on when I actually build the huffman tree structs (theora_decode_init, calls InitHuffmanSet()).  At that point the original header packet is gone so I've been keeping it around in a buffer.  Gross!!
> Someone please help.  This is likely the last bitstream change before we lock it down for Beta, so I want to get it right.
>  ___  Dan Miller


if you need your trees for decoding, make sure you can read them from an
element that can be easily accessed in the container from outside. If
you plan to have DirectShow support for Theora on Windows, bare in mind
DShow needs to know this stuff *BEFORE* building the graph. You can not
build the DShow graph and then read some chunks of data to initialize
your decoder correctly, unless this stuff doesnt change anything vital
in the decoding graph affecting the graph itself ( resolution, colour
space output, etc. ).... this is, assuming you plan to have a Theora
splitter/parser filter on DShow and a Theora decoder filter as separate
elements in the playback chain ....


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