fix bug for blank audio (#1656)

jianganghan

2024-04-25 f8b4924060bb849680925e81ddf1e10ca406c225

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wget https://isv-data.oss-cn-hangzhou.aliyuncs.com/ics/MaaS/ASR/dep_libs/ffmpeg-N-111383-g20b8688092-linux64-gpl-shared.tar.xz
tar -xvf ffmpeg-N-111383-g20b8688092-linux64-gpl-shared.tar.xz