diff options
Diffstat (limited to 'doc/draft-ietf-codec-opus.xml')
| -rw-r--r-- | doc/draft-ietf-codec-opus.xml | 38 |
1 files changed, 35 insertions, 3 deletions
diff --git a/doc/draft-ietf-codec-opus.xml b/doc/draft-ietf-codec-opus.xml index 2c767e08..4e2a808e 100644 --- a/doc/draft-ietf-codec-opus.xml +++ b/doc/draft-ietf-codec-opus.xml @@ -1226,7 +1226,7 @@ Each CELT frame can be encoded in a different number of octets, making it possib </section> -<section title="Codec Decoder"> +<section title="Opus Decoder"> <t> Opus decoder block diagram. </t> @@ -1556,6 +1556,26 @@ in celt_decode_lost() (mdct.c). </section> +<section title="Conformance"> + +<t> +It is the intention to allow the greatest possible choice of freedom in +implementing the specification. For this reason, outside of a few exceptions +noted in this section, conformance is defined through the reference +implementation of the decoder provided in Appendix <xref target="ref-implementation"></xref>. +Although this document includes an English description of the codec, should +the description contradict the source code of the reference implementation, +the latter shall take precedence. +</t> + +<t> +Compliance with this specification means that a decoder's output MUST be +<spanx style="emph">close enough</spanx> to the output of the reference +implementation. This is measured using the opus_compare.m tool provided in +Appendix <xref target="opus-compare"></xref>. +</t> +</section> + <section anchor="security" title="Security Considerations"> <t> @@ -1569,8 +1589,14 @@ audio stream must not cause the encoder to misbehave because this would allow an attacker to attack transcoding gateways. </t> <t> -In its current version, the Opus codec likely does NOT meet these -security considerations, so it should be used with caution. +The reference implementation contains no known buffer overflow or cases where +a specially crafter packet or audio segment could cause a significant increase +in CPU load. However, on certain CPU architectures where denormalized +floating-point operations result and handled through exceptions, it is possible +for some audio content (e.g. silence or near-silence) to cause such an increase +in CPU load. For such architectures, it is RECOMMENDED to add very small +floating-point offsets to prevent significant numbers of denormalized +operations. No such issue exists for the fixed-point reference implementation. </t> </section> @@ -1790,6 +1816,12 @@ tar xzvf opus_source.tar.gz </section> +<section anchor="opus-compare" title="opus_compare.m"> +<t> +<?rfc include="opus_compare_escaped.m"?> +</t> +</section> + </back> </rfc> |