Is there a way to use ffmpeg to determine the encoding of a file before transcoding?

问题

I am planning to use ffmpeg to ensure all video files uploaded to my website are encoded as mp4 h264.

Rather than automatically processing every file I would like to minimise the processing overhead by only processing those files that are not already mp4 h264. Is there an easy way to do this either with ffmpeg or with another command line utility?

回答1:

If you pass an input file to ffmpeg, without other parameters, it will give you information about the video source:

ffmpeg -i myfile.avi

Another way would be the -identify option of mplayer, which might be slightly easier to parse. There is a wrapper script midentify which gives you even better output. See this example.

回答2:

Use ffprobe.

Example command

$ ffprobe -v error -select_streams v:0 -show_entries stream=codec_name -of default=nokey=1:noprint_wrappers=1 input.mp4

Result

h264

Option descriptions

• -v error Omit extra information except for fatal errors.

• -select_streams v:0 Select only the first video stream. Otherwise the codec_name for all other streams in the file, such as audio, will be shown as well.

• -show_entries stream=codec_name Only output the codec_name instead of all stream info.

• -of default=nokey=1:noprint_wrappers=1 Select the default output format style and omit the key and wrapper info. Otherwise, without these options, it will output:

  [STREAM]
  codec_name=h264
  [/STREAM]
  

Also see

• ffprobe documentation
• FFmpeg Wiki: FFprobe Tips

回答3:

An alternative is to use ffprobe which is included with ffmpeg. The following will give the most terse output I can find from the ffmpeg tools:

ffprobe -hide_banner -stats -i myfile.avi

来源：https://stackoverflow.com/questions/5618363/is-there-a-way-to-use-ffmpeg-to-determine-the-encoding-of-a-file-before-transcod