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I am trying to find out why the result of using scale2ref with overlay complex filters is returning audio-only mp4 output.

ffmpeg -i input.mp4 -i watermark.png -filter_complex "[1][0]scale2ref=w=oh*mdar:h=ih*0.1[logo][video];[video][logo]overlay=5:H-h-5" -c:a copy output.mp4

If I remove the scale2ref filter, then the output is a mp4 video.

ffmpeg -i input.mp4 -i watermark.png -filter_complex "overlay=5:H-h-5" -c:a copy output.mp4

One of the differences between the two is this line in the output:

[vost#0:0/libx264 @ 0x10f605de0] No filtered frames for output stream, trying to initialize anyway.

I am new to ffmpeg, any help will be appreciated.

Link to the log file

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  • Which version ?
    – Gyan
    Commented May 2 at 4:25
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    @Gyan latest 7.0 according to log.
    – Destroy666
    Commented May 2 at 12:16
  • 2
    try to add -loop 1 → ffmpeg -i "input.mp4" -loop 1 -i watermark.png -lavfi " [1][0]scale2ref=w=oh*mdar/sar:h=ih/10[l][v]; [v][l]overlay=5:H-h-5:shortest=1" output.mp4
    – Баяр Гончикжапов
    Commented May 2 at 13:55
  • Thanks, @БаярГончикжапов! I can see the output with audio and video however the command never finishes. I had to interrupt manually. The output before interruption was: frame=942170 fps=2243 q=-1.0 Lsize= 180036KiB time=00:07:56.91 bitrate=3092.5kbits/s dup=154642 drop=0 speed=1.14x Could this be due to the -loop 1 option?
    – Sushil
    Commented May 3 at 6:23
  • check this option of overlay → ...:shortest=1
    – Баяр Гончикжапов
    Commented May 3 at 12:07

2 Answers 2

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It looks like the 'scale2ref' filter is broken in the latest version of FFmpeg. It has been deprecated.

I have been experiencing the same problem as you, and when I tried some tricks to get around it, I got Assertion best_input >= 0 failed.

That led me to this question, and it also led me to this issue in the FFmpeg issue tracker: https://trac.ffmpeg.org/ticket/10795.

The 'scale2ref' filter was officially deprecated in this commit: https://github.com/FFmpeg/FFmpeg/commit/95568c4e316e8f5f3252596b1f01ce1de22216b6.

According to some of the commit messages and the communication in that issue, the FFmpeg developers plan to replace 'scale2ref' with the 'scale' filter by adding new reference options 'ref_w' and 'ref_h' to achieve the same functionality.

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As mentioned in other comments, scale2ref is deprecated. If you're using a recent version of ffmpeg, you should use scale=rw:rh instead when using a reference to scale. Since scale has only one output, just remove the tag [video] after the filter and replace its use with the second input used with scale2ref.

The command would end up as below:

ffmpeg -i input.mp4 -i watermark.png -filter_complex "[1][0]scale=w=oh*mdar:h=rh*0.1[logo];[0][logo]overlay=5:H-h-5" -c:a copy output.mp4

In summary:

  • Replace scale2ref with scale
  • Replace any iw and ih with rw and rh
  • Leave only one output after scale
  • Replace any use of the second output of scale2ref with its second input
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