FFmpeg Convert to JPEG works in VLC but not in Mac Preview?

Question

I'm trying to convert a PNG image to a JPEG image using ffmpeg. As far as I can tell, it's working fine, but it doesn't display properly in Mac Preview.

I'm running the following:

$ ffmpeg -i foo.png foo.jpg

And it produces the following output:

ffmpeg version 4.1.3 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple LLVM version 10.0.0 (clang-1000.11.45.5)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/4.1.3_1 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags='-I/Library/Java/JavaVirtualMachines/adoptopenjdk-11.0.2.jdk/Contents/Home/include -I/Library/Java/JavaVirtualMachines/adoptopenjdk-11.0.2.jdk/Contents/Home/include/darwin' --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libbluray --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libsnappy --enable-libtesseract --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-videotoolbox --disable-libjack --disable-indev=jack --enable-libaom --enable-libsoxr
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, png_pipe, from 'foo.png':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: png, rgba(pc), 200x231, 25 tbr, 25 tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (png (native) -> mjpeg (native))
Press [q] to stop, [?] for help
[swscaler @ 0x7ffeaf00ae00] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'foo.jpg':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0: Video: mjpeg, yuvj444p(pc), 200x231, q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
    Metadata:
      encoder         : Lavc58.35.100 mjpeg
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
frame=    1 fps=0.0 q=3.7 Lsize=N/A time=00:00:00.04 bitrate=N/A speed= 4.7x    
video:12kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

When I open foo.jpg in most applications, such as VLC or Google Chrome, I get exactly what I expected: an image that looks exactly the same as foo.png, the input.

However, this is what is displayed in the Finder preview, and the same this is displayed when I open up the file in "Preview."

~~~I wonder if this has something to do with the deprecated pixel format used, make sure you did set range correctly error, but I'm not sure, especially since the image is fine, the problem seems to be elsewhere.~~~

It seems the deprecated pixel format error is not the issue (that's an internal thing), so I guess I just need to specify pixel formats properly.

Answer 1

Looks like QT / AVFoundation doesn't like fully-sampled chroma in JPEG.

First try

ffmpeg -i foo.png -pix_fmt yuvj422p foo.jpg

else,

ffmpeg -i foo.png -pix_fmt yuvj420p foo.jpg

The warning about deprecated format relates to ffmpeg internals and not the produced output.