MediaConch (incorrectly?) identifies errors in 2-pass encoded FFV1 files: invalid values for "ec" / fails strict validation

[JohnstonJ]

MediaConch 24.06 identifies problems in FFV1 files that were encoded using FFmpeg's 2-pass encoding feature. The FFmpeg project suspects that there is not a bug in FFmpeg, so it might be a bug in MediaConch.

Here are the corresponding FFmpeg bug reports, with far more details in each and sample attached files:

• https://trac.ffmpeg.org/ticket/11127 - FFV1 sometimes encodes invalid values for "ec" (CRC error detection/correction) header parameter field when using 2-pass encoding
  • Summary: FFV1 sometimes encodes invalid values for the "ec" header parameter, which declares the CRC error detection/correction type. This results in the file failing validation in both MediaConch and MediaInfo.
  • MediaConch fails verification with: FFV1-HEADER-ec
  • 
• https://trac.ffmpeg.org/ticket/11128 - FFV1 encodes files that fail strict 3rd-party MediaConch validation when using 2-pass encoding
  • Summary: FFmpeg / FFV1 encodes FFV1 slices that fail multiple MediaConch validation rules when using 2-pass encoding.
  • MediaConch fails verification with: FFV1-SLICE-SliceContent
  • 

I initially suspected these might be bugs in FFmpeg. However, maybe it's a verification bug in MediaConch?