ffmpeg的错误码有时候很大，为了方便辨认这里做个记录：

AVERROR_BSF_NOT_FOUND = -1179861752
AVERROR_BUG = -558323010
AVERROR_DECODER_NOT_FOUND = -1128613112
AVERROR_DEMUXER_NOT_FOUND = -1296385272
AVERROR_ENCODER_NOT_FOUND = -1129203192
AVERROR_EOF = -541478725
AVERROR_EXIT = -1414092869
AVERROR_FILTER_NOT_FOUND = -1279870712
AVERROR_INVALIDDATA = -1094995529
AVERROR_MUXER_NOT_FOUND = -1481985528
AVERROR_OPTION_NOT_FOUND = -1414549496
AVERROR_PATCHWELCOME = -1163346256
AVERROR_PROTOCOL_NOT_FOUND = -1330794744
AVERROR_STREAM_NOT_FOUND = -1381258232
AVERROR_BUG2 = -541545794
AVERROR_UNKNOWN = -1313558101