Hello, I've been writing a decoder using the spec and it's unclear to me where the value [lookup_offset] comes from when performing VQ vector value decode (page 23 of the spec). The wording in the spec is very confusing to me. Someone asked this question before ( http://lists.xiph.org/pipermail/vorbis-dev/2002-September/015282.html ), but it went unanswered. Could anyone help me (and anyone in the future) understand where this value is coming from?
On Sun, Apr 21, 2013 at 11:24 AM, N. Sidorova <n.sidorova at lunanite.com> wrote:> Hello, > > I've been writing a decoder using the spec and it's unclear to me where > the value [lookup_offset] comes from when performing VQ vector value > decode (page 23 of the spec). The wording in the spec is very confusing > to me. Someone asked this question before ( > http://lists.xiph.org/pipermail/vorbis-dev/2002-September/015282.html ), > but it went unanswered. > > Could anyone help me (and anyone in the future) understand where this > value is coming from?I assume you're talking about section 3.2.1. A codebook conceptually consists of a list of vectors; the input_offset is the number of a given vector in the list. The pseudocode is showing the decoding process for a single one of those vectors; there's an implied higher level loop that is decoding each vector in turn. Monty
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