ref: f21970a65772fb189539f13dbb27bf2d9174ca8b
parent: 44f87362fbc10b64a5f2ece564c55f242cbde9b7
author: Timothy B. Terriberry <[email protected]>
date: Fri Jan 15 10:57:49 EST 2016
Docuemnt the source of the 2.5 ms and 48 kHz restrictions. Thanks to Joel Halpern for the suggestion.
--- a/doc/draft-ietf-codec-oggopus.xml
+++ b/doc/draft-ietf-codec-oggopus.xml
@@ -248,14 +248,16 @@
The granule position of an audio data page is in units of PCM audio samples at
a fixed rate of 48 kHz (per channel; a stereo stream's granule position
does not increment at twice the speed of a mono stream).
-It is possible to run an Opus decoder at other sampling rates, but the value
- in the granule position field always counts samples assuming a 48 kHz
- decoding rate, and the rest of this specification makes the same assumption.
+It is possible to run an Opus decoder at other sampling rates, but all of them
+ evenly divide 48 kHz.
+Therefore, the value in the granule position field always counts samples
+ assuming a 48 kHz decoding rate, and the rest of this specification makes
+ the same assumption.
</t>
<t>
-The duration of an Opus packet can be any multiple of 2.5 ms, up to a
- maximum of 120 ms.
+The duration of an Opus packet as defined in <xref target="RFC6716"/> can be
+ any multiple of 2.5 ms, up to a maximum of 120 ms.
This duration is encoded in the TOC sequence at the beginning of each packet.
The number of samples returned by a decoder corresponds to this duration
exactly, even for the first few packets.