FFMPEG option order

ffmpeg [global_options] {[input_file_options] -i input_file} ... {[output_file_options] output_file} ...

 

As a general rule, options are applied to the next specified file. Therefore, order is important, and you can have the same option on the command line multiple times.Each occurrence is then applied to the next input or output file.Exceptions from this rule are the global options (e.g. verbosity level), which should be specified first.

 

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例如：

./ffmpeg-re -analyzeduration 10M-probesize10M -i rtmp://test/myapp/teststream  -report -acodec libfaac -vcodec libx264 -profile:v high -level:v 40 -preset medium  -r 30 -b:v 800k  -profile:a aac_low -ar 48000 -ac 2 -s 200x200 -f flv rtmp://test/myapp/newstream

 -analyzeduration   和-probesize    必须放到-i之前，否则不起作用。也就是说这两个参数是输入文件的选项

-tduration(input/output)

When used as an input option (before-i), limit thedurationof data read from the input file.

When used as an output option (before an output filename), stop writing the output after its duration reachesduration.

durationmay be a number in seconds, or inhh:mm:ss[.xxx]form.

-to and -t are mutually exclusive and -t has priority.

./ffmpeg -t 1 -i test.ts -c copy -vcodec libx264 -y out.ts
解码了25 frames

 ./ffmpeg -report  -i test.ts -c copy -t 1 -vcodec libx264 -y out.ts
编码了25 frames

注释：test.ts的码率为25