1. 空的：压缩的时候,有一定的 bitrate,如果前面的画面太难压缩,用掉太多 bit,到了这个画面时 bit 用光了,无法分配 bit 给这个画面使用,这时这个Frame 无法压缩,只好 drop 掉, 产生一个空的(Null) Frame.

2. null的翻译

2. 无效：由于本文采用间接法计算应力场,因此模型建立与网格剖分必须与温度场的计算模型相同,将空气与感应线圈单元设为无效(NULL)单元,温度场所用单元PLANE55转换为结构单元PLANE42,保持单元数与结点数不变.

3. null：nul; 空行;空值

1. (协议、宣言或选举结果)无法律效力的，无效的
    If an agreement, a declaration, or the result of an election is null and void, it is not legally valid.

    e.g. A spokeswoman said the agreement had been declared null and void...
           女发言人称该协议已宣布无效。
    e.g. The declaration was null and void as it was proclaimed in completely illegal circumstances.
           该声明无效，因为它是在完全非法的情况下宣布的。

1. a quantity of no importance

    e.g. it looked like nothing I had ever seen before
           reduced to nil all the work we had done
           we racked up a pathetic goose egg
           it was all for naught
           I didn''t hear zilch about it

    Synonym: nothingnilnixnadaaughtciphercyphergoose eggnaughtzerozilchzipzippo

1. lacking any legal or binding force

    e.g. null and void

    Synonym: void