[theora-dev] Dynamically changeable parameters in theora

Maik Merten maikmerten at gmx.net
Tue Oct 30 11:49:20 PDT 2007


as a rule of thumb you cannot on-the-fly change those things that are
transmitted in the header, which includes:

 - quant tables
 - loop filter limits
 - scale values
 - frame dimension
 - framerate
 - colorspace
 - color plane subsampling

etc. (list not complete)

You can, however, e.g. change the quality value for each frame (and even
for each block with certain restrictions) - which means you can choose
what quant values get applied. This is the normal mode of operation for
basically every bitrate management solution on the field of video coding.

Albeit one cannot change the framerate you can decide to drop frames.

If you want to make bigger changes you can always append a new Theora
stream with a new set of parameters to an Ogg stream. Players MUST
support concatenation, but most don't do this properly (seeking problems
etc.) - but for online streaming without seeking etc. I think most
players offer "usable" support.

Maik Merten

janaka priyadarshana schrieb:
> hi all,
> please can anyone tell me that what are the possible parameters in
> theora codec, that can be changed dynamically in execution time like
> DCT coefficient matrix
> frame rate....etc. ( still i do not know whether those are dynamically
> changeable)

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