Errata

Status:

Verified

Type:

Technical

Reported By:

Rostislav Pehlivanov

Date Reported:

2016-11-02

Verified by:

Ben Campbell

Date Verified:

2016-11-02

Section 5.1.1 says:

                                    rng
                        rng = rng - --- * (fh - fl)
                                    ft

It should say:

                                    rng
                        rng = rng - --- * (ft - fh)
                                    ft

Notes:

Equation should match with the one in the range decoder (section 4.1.2), however comparing the two and the reference implementation reveals the equation in section 5.1.1 to be incorrect.

Status:

Reported

Type:

Technical

Reported By:

Albert Mao

Date Reported:

2026-04-15

Section 4.3.7 says:

                                                         2
                          /   /pi      /pi   n + 1/2\ \ \
                   W(n) = |sin|-- * sin|-- * -------| | |
                          \   \2       \2       L   / / /

It should say:

                                      2
                             /pi       /pi   n + 1/2\ \
                   W(n) = sin|-- * sin |-- * -------| |
                             \2        \2       L   / /

Notes:

The Vorbis specification and the Opus reference implementation have the exponent 2 squaring the inner sine function, but RFC 6716 has it squaring the outer sine function.

Status:

Held for Document Update

Type:

Technical

Reported By:

Peter Budny

Date Reported:

2015-06-15

Held for Document Update by:

Ben Campbell

Date Held for Document Update:

2015-06-15

Section 2 says:

The Opus codec scales from 6 kbit/s narrowband mono speech to
510 kbit/s fullband stereo music, with algorithmic delays ranging
from 5 ms to 65.2 ms.

(further in the same section)

To
compensate for the different look-ahead required by each layer, the
CELT encoder input is delayed by an additional 2.7 ms.

It should say:

The Opus codec scales from 6 kbit/s narrowband mono speech to
510 kbit/s fullband stereo music, with algorithmic delays ranging
from 5 ms to 66.5 ms.

(further in the same section)

To
compensate for the different look-ahead required by each layer, the
CELT encoder input is delayed by an additional 4 ms.

Notes:

For the latter text, the delays for the CELT and SILK layers must match.  SILK has a "5 ms look-ahead for noise shaping estimation", and "1.5 ms delay for sampling rate conversion", totaling 6.5 ms.  CELT has a "2.5 ms look-ahead due to the overlapping MDCT windows".  Thus, the amount of delay needed to align CELT with SILK is 6.5ms - 2.5ms = 4ms.

The text at the beginning of the section must reflect this as well.  The "algorithmic delays" reported apparently include framing (minimum frame size 2.5ms + look-ahead delay in CELT-only mode 2.5ms = 5ms).  In that case, the maximum delay is the maximum frame size (60ms) + the maximum delay for look-ahead and resampling (6.5ms) = 66.5ms.

Confirmed by author ("Jmvalin") at https://en.wikipedia.org/wiki/Talk:Opus_(audio_format)/Archive_1#Codec_delay_values

Status:

Held for Document Update

Type:

Editorial

Reported By:

flacs

Date Reported:

2016-10-12

Held for Document Update by:

Ben Campbell

Date Held for Document Update:

2016-11-02

Throughout the document, when it says:

Coeffieients

It should say:

Coefficients

Notes:

Just a small typo in the Table of Contents.