FFMPEG下常用命令参数

本篇文章作为自己将FFMPEG下一些命令的记录与学习，以供学习：

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命令参数讲解：

    -i 'udp://localhost:5000?fifo_size=1000000&overrun_nonfatal=1' tells ffmpeg where to pull the input stream from. The parts after the ? are probably not needed most of the time, but I did need it after all.    -crf 30 sets the Content Rate Factor. That's an x264 argument that tries to keep reasonably consistent video quality, while varying bitrate during more 'complicated' scenes, etc. A value of 30 allows somewhat lower quality and bit rate. See Encode/H.264.    -preset ultrafast as the name implies provides for the fastest possible encoding. If some tradeoff between quality and encode speed, go for the speed. This might be needed if you are going to be transcoding multiple streams on one machine.    -acodec aac sets the audio codec (internal AAC encoder)    -strict experimental allows use of some experimental codecs (the internal AAC encoder is experimental)    -ar 44100 set the audio sample rate    -ac 2 specifies two channels of audio    -b:a 96k sets the audio bit rate    -vcodec libx264 sets the video codec    -r 25 set the frame rate    -b:v 500k set the video bit rate    -f flv says to deliver the output stream in an flv wrapper    'rtmp://<wowza server IP>/live/cam0' is where the transcoded video stream gets pushed to

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