[Feature] Add audio demo

[Dai-Wenxun]

Motivation

Add audio demo

[codecov]

Codecov Report

Patch coverage: 28.57% and project coverage change: -0.03 ⚠️

Comparison is base (c548788) 76.18% compared to head (b2517b3) 76.16%.

❗ Current head b2517b3 differs from pull request most recent head 4ba613f. Consider uploading reports for the commit 4ba613f to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           dev-1.x    #2603      +/-   ##
===========================================
- Coverage    76.18%   76.16%   -0.03%     
===========================================
  Files          170      170              
  Lines        13792    13797       +5     
  Branches      2361     2363       +2     
===========================================
+ Hits         10507    10508       +1     
- Misses        2718     2720       +2     
- Partials       567      569       +2     

Flag	Coverage Δ
unittests	76.16% <28.57%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmaction/apis/inference.py	79.59% <28.57%> (-3.21%)	⬇️

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