ffmpeg does not copy audio file's cover art when start time in not zero

[zymos]

Summary of the bug:
When converting an audio file with cover art in metadata/id3, with the start time(-ss) option used. The cover art is not copied, no matter how the the "cover art/video/visual" element is attempted to be copied.

• -codec copy
• -c:v copy
• -c:v png
• -c:v mjpeg

I believe this is because the cover art is treated as a single frame of video at time zero, and when start time is not zero, there is no video. Obviously cover art is not a video stream, but I'm guessing this was done as a work around. But that's only my guess

How to reproduce:

* Use any audio file with cover art in metadata/id3
* Convert file with a non-zero start time
* Audio is copied as expected, metadata is copied as expected, no cover art

% fmpeg -i sample.mp3 -ss 10 -codec copy output-start-at-10-sec.mp3


ffmpeg version
ffmpeg version 4.2.4-1ubuntu0.1 Copyright (c) 2000-2020 the FFmpeg developers
built with gcc 9 (Ubuntu 9.3.0-10ubuntu2)
configuration: --prefix=/usr --extra-version=1ubuntu0.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-nvenc --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
libavutil      56. 31.100 / 56. 31.100
libavcodec     58. 54.100 / 58. 54.100
libavformat    58. 29.100 / 58. 29.100
libavdevice    58.  8.100 / 58.  8.100
libavfilter     7. 57.100 /  7. 57.100
libavresample   4.  0.  0 /  4.  0.  0
libswscale      5.  5.100 /  5.  5.100
libswresample   3.  5.100 /  3.  5.100
libpostproc    55.  5.100 / 55.  5.100

[Balling]

ffmpeg -ss 10 -i C:\Users\ZAQU\Downloads\sample.mp3 -c copy fcnaqwsc.mp3

works here. -ss option before -i.