解决VideoReader出现Thread worker: Error sending packet报错

• 问题现象：对于个别视频，单独读取该视频是正常，使用decord中的VideoReader读取会报如下的错误：

06:56:29 /github/workspace/src/video/ffmpeg/threaded_decoder.cc:292: 06:56:29 /github/workspace/src/video/ffmpeg/threaded_decoder.cc:218: Check failed: avcodec_send_packet(dec_ctx_.get(), pkt.get()) >= 0 (-11 vs. 0) Thread worker: Error sending packet.

• 问题定位：

# vr = VideoReader(video_path, ctx=cpu(0), num_threads=4)
vr = VideoReader(video_path, ctx=cpu(0), num_threads=1)

将线程数量设为1即可解决。初步怀疑是decord库在多线程处理某些视频时存在问题。