Run ffmpeg multiple commands

问题:

Im using this ffmpeg command to convert mp3 to wav:

ffmpeg -i audio.mp3 -acodec libmp3lame -ab 64k -ar 16000 audio.wav

and this command to create waveform from audio.wav:

wav2png --foreground-color=ffb400aa --background-color=2e4562ff -o example4.png papa2.wav

I would love to know, how to run this commands multiple? For example, when conversion from .mp3 to .wav is done, then run the wav2png command.

Thank You!

回答1:

You have several options here:

Option 1: Use &&

In Bash you can use an and list to concatenate commands. Each command will be executed one after the other. The and list will terminate when a command fails, or when all commands have been successfully executed.

ffmpeg -i audio.mp3 audio.wav && wav2png -o output.png audio.wav

• Using -acodec libmp3lame when outputting to WAV makes no sense, so I removed that.

• WAV ignores bitrate options, so I removed -ab.

• Do you really need to change the audio rate (-ar)? Removed.

Option 2: Pipe from ffmpeg to wav2png

Instead of making a temporary WAV file you can pipe the output from ffmpeg directly to wav2png:

ffmpeg -i audio.mp3 -f wav - | wav2png -o output.png /dev/stdin

Option 3: Just use ffmpeg

Saving the best for last, you can try the showwavespic filter.

ffmpeg -i music.wav -filter_complex showwavespic=s=640x320 showwaves.png

• If you want to make a video of the wave form, then try showwaves.
• You can see a colored example at Generating a waveform using ffmpeg.