numberOfChannels/sampleRate check in AudioDecoderConfig/AudioEncoderConfig

[chrisguttandin]

Right now a valid AudioEncoderConfig needs to have a numberOfChannels and a sampleRate property greater than zero.

https://w3c.github.io/webcodecs/#valid-audioencoderconfig

A similar check does not exist to validate an AudioDecoderConfig.

https://w3c.github.io/webcodecs/#valid-audiodecoderconfig

Chrome seems to perform the same non-zero checks for an AudioEncoderConfig and AudioDecoderConfig. But as far as I can tell they are not covered by a WPT.

The checks for an AudioEncoderConfig were added here: #780.

[padenot]

Yeah, we talked about harmonizing implem and tests in an issue not too long ago, but I can't find it.

For decoding, it's not 100% required to provide the sample-rate and the channel count, sometimes it's possible to determine them from the bit stream. Sometimes it is required though.

For encoding, it's always required.