PSNR filter not returning error with different input formats

[govind]

I am expecting the psnr-filter to return with error message "Inputs must be of same pixel format." if I try to run it on two inputs with different pixel format. But it is going ahead with the processing.
I don't know if this is the default behavior. But even if one of the input, again it is not sure which one, is undergoing reformatting before being fed to the psnr-filter, shouldn't it warn user about what is happening internally?

How to reproduce:

% ffmpeg -f rawvideo -s:v 1280x720 -pix_fmt yuv422p -i input1.yuv -f rawvideo -s:v 1280x720 -pix_fmt yuv420p -i input2.yuv -filter_complex psnr -f null -

ffmpeg version 2.5.git Copyright (c) 2000-2014 the FFmpeg developers
  built on Dec 14 2014 15:08:09 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
  configuration: 
  libavutil      54. 15.100 / 54. 15.100
  libavcodec     56. 14.100 / 56. 14.100
  libavformat    56. 15.105 / 56. 15.105
  libavdevice    56.  3.100 / 56.  3.100
  libavfilter     5.  3.101 /  5.  3.101
  libswscale      3.  1.101 /  3.  1.101
  libswresample   1.  1.100 /  1.  1.100

built on Ubuntu14.04

Patches should be submitted to the ffmpeg-devel mailing list and not this bug tracker.

[Carl Eugen Hoyos]

Please always add the complete, uncut console output if you open a ticket on this bug tracker.

From a quick look, the psnr filter does print an error if it is called with two streams with different pix_fmts but this is not the case when using ffmpeg: It makes sure that a common pix_fmt is chosen and the console output should show this.

[Elon Musk]

ffmpeg picks format and there is nothing that can be fixed from filter level.

[Cigaes]

Actually, there is. Look for “if pix_fmt is a single +” in the documentation.

[Elon Musk]

What documentation?

[Clément Bœsch]

Replying to richardpl:

What documentation?

​http://ffmpeg.org/ffmpeg.html#Advanced-Video-options