DVR: support mp3 audio codec

[duiniuluantanqin]

No description provided.

[codecov-commenter]

Codecov Report

Merging #2593 (eb90d77) into develop (a830289) will increase coverage by 0.04%.
The diff coverage is 95.83%.

@@             Coverage Diff             @@
##           develop    #2593      +/-   ##
===========================================
+ Coverage    59.24%   59.29%   +0.04%     
===========================================
  Files          122      122              
  Lines        51741    51803      +62     
===========================================
+ Hits         30653    30715      +62     
  Misses       21088    21088              

| Impacted Files | Coverage Δ | |'

Translated to English while maintaining the markdown structure:

'| Impacted Files | Coverage Δ | |
|---|---|---|
| trunk/src/app/srs_app_dvr.cpp | 0.00% <0.00%> (ø) | |
| trunk/src/kernel/srs_kernel_mp4.hpp | 100.00% <ø> (ø) | |'

Translated to English while maintaining the markdown structure:

'| trunk/src/app/srs_app_dvr.cpp | 0.00% <0.00%> (ø) | |
| trunk/src/kernel/srs_kernel_mp4.hpp | 100.00% <ø> (ø) | |
| trunk/src/kernel/srs_kernel_mp4.cpp | 88.61% <87.50%> (-0.01%) | ⬇️ |
| trunk/src/kernel/srs_kernel_codec.cpp | 90.09% <100.00%> (+0.01%) | ⬆️ |
| trunk/src/utest/srs_utest_kernel.cpp | 98.52% <100.00%> (+0.02%) | ⬆️ |
| trunk/src/protocol/srs_rtmp_handshake.cpp | 84.13% <0.00%> (+0.17%) | ⬆️ |

---

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Δ = absolute <relative> (impact), ø = not affected, ? = missing data'

Translated to English while maintaining the markdown structure:

'> Δ = absolute <relative> (impact), ø = not affected, ? = missing data

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TRANS_BY_GPT3

[winlinvip]

Merged as eac8996