[theora-dev] Theora Data Dump?

Tony O'Bryan theoradev at tonyobryan.com
Sat Feb 20 11:05:49 PST 2010

On Saturday February 20 2010, Timothy B. Terriberry wrote:

> Not that I know of. I've considered adding an example like this as an
> appendix to the spec, but never found the time.

While writing my decoder, I posted some of the data structures I've read from 
the first 320x240.ogg example file, and which match the numbers read by the 
dump-video program, to the theora mailing list.  I can repost them here if 
you'd like to include them in a future appendix.

> Please let us know if you find areas of the spec unclear, or have other
> specific questions that are not answered in it.

Section 6.4.3 of the specification (Computing a Quantization Matrix) says:

1. Assign qri the index of a quant range such that

qi >= summation from qrj=0 to qri-1 (QRSIZES[qti][pli ][qrj ])


qi <= summation from qrj=0 to qri (QRSIZES[qti ][pli ][qrj ])

How do I determine which qri to select so that qi will fall between the 
specified value range?  Or will a valid Theora file always result in a summation 
that automatically satisfies that requirement, regardless of which qri I 

More information about the theora-dev mailing list