riff-media: Align channel-mask to channels

Submitted by HoonHee Lee

Link to original bug (#797108)

Description

Dear All.

I have abnormal stream.

Please look attached file.

As I check the codec, it is GST_RIFF_WAVE_FORMAT_EXTENSIBLE, and channel-mask parse from codec_buffer. But the channel-mask does not match the channel value.

So, audio mute symptom is observed.

If I change channel-mask from 0x03 (2 channels) to 0x3f (6 channels), it could playback well.

Thanks.

Version: 1.14.0