CODEWITHSUNDEEP
ffmpeg
edwardsmarkf
edwardsmarkf

Reputation: 1417

using ffmpeg to create a wavefile image from opus

I have been trying to use ffmpeg to create a wavefile image from an opus file. so far i have found three different methods but cannot seem to determine which one is the best.

The end result is hopefully to have a sound-wave that is only approx. 55px in height. The image will become part of a css background-image.

Adapted from Generating a waveform using ffmpeg:

ffmpeg -i file.opus -filter_complex "showwavespic,colorbalance=bs=0.5:gm=0.3:bh=-0.5,drawbox=x=(iw-w)/2:y=(ih-h)/2:w=iw:h=1:[email protected]" file.png

which produces this image: enter image description here

Next, I found this one (and my favorite because of the simplicity):

ffmpeg -i test.opus -lavfi showwavespic=split_channels=1:s=1024x800 test.png

And here is what that one looks like:

enter image description here

Finally, this one from FFmpeg Wiki: Waveform, but it seems less efficient using a second utility (gnuplot) rather than just ffmpeg:

ffmpeg -i file.opus -ac 1 -filter:a aresample=4000 -map 0:a -c:a pcm_s16le -f data - | \ gnuplot -e "set terminal png size 525,050;set output 'file.png';unset key;unset tics;unset border; set lmargin 0;set rmargin 0;set tmargin 0;set bmargin 0; plot '

enter image description here

Option two is my favorite, but i dont like the margins on the top and bottom of the waveforms.

Option three (using gnuplot) makes the best 'shaped' image for our needs, since the initial spike in sound seems to make the rest almost too small to use (lines tend to almost disappear) when the image is sized at only 50 pixels high.

Any suggestions how might best approach this? I really understand very little about any of the options I see, except of course for the size. Note too i have 10's of thousands to process, so naturally i want to make a wise choice at the very beginning.

Upvotes: 3

Views: 1568

Answers (1)

llogan
llogan

Reputation: 133973

enter image description here enter image description here
Original and manipulated waveforms.

You can use the compand filter to adjust the dynamic range. drawbox is then used to make the horizontal line.

ffmpeg -i test.opus -filter_complex \
"compand=gain=-6,showwavespic=s=525x50, \
 drawbox=x=(iw-w)/2:y=(ih-h)/2:w=iw:h=1:color=white" \
-vframes 1 output.png

It won't be quite as accurate of a representation of your audio as the original waveform, but it may be an improvement visually; especially on such a wide scale.

Also see FFmpeg Wiki: Waveform.

Upvotes: 4

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