What are the differences and similarities between ffmpeg, libav, and avconv?

問題：

When I run ffmpeg on Ubuntu, it shows:當我在 Ubuntu 上運行ffmpeg時，它顯示：

$ ffmpeg 
ffmpeg version v0.8, Copyright (c) 2000-2011 the Libav developers
  built on Feb 28 2012 13:27:36 with gcc 4.6.1
This program is not developed anymore and is only provided for compatibility. Use avconv instead (see Changelog for the list of incompatible changes).

Or it shows (depending on the Ubuntu version):或者它顯示（取決於 Ubuntu 版本）：

$ ffmpeg
ffmpeg version 0.8.5-6:0.8.5-0ubuntu0.12.10.1, Copyright (c) 2000-2012 the Libav developers
  built on Jan 24 2013 14:49:20 with gcc 4.7.2
*** THIS PROGRAM IS DEPRECATED ***
This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.

I found avconv on http://libav.org .我在http://libav.org上找到了 avconv。 I am just perplexed by them.我只是被他們弄糊塗了。

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解決方案：

參考一： https://en.stackoom.com/question/dlQh
參考二： https://stackoom.com/question/dlQh