How to find which of two AVI files that should be equal has an error?

Question

I've got two very large AVI files that are supposedly backup copies of one another. They differ in exactly one bit (yes bit, not even a byte):

Windows "fc /b" reports the following as the only difference:

3759B86F: B1 B3

ffmpeg -v error reports same errors on both. Otherwise they are:

 Duration: 00:33:33.17, start: 0.000000, bitrate: 30317 kb/s
   Stream #0:0: Video: dvvideo (dvsd / 0x64737664), yuv411p, 720x480 [SAR 8:9 DAR 4:3],     29.97 tbr, 29.97 tbn, 29.97 tbc
   Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s

They are huge (7,629,216,528 bytes - >7 GB) and I want to keep only the right one... but can't figure out which one it is...

EDIT I lied. ffmpeg reports same KINDS of errors BUT at different locations (03D... for one file and 03C... for another):

...>ffmpeg -v error -i file1.avi -f null -
[dvvideo @ 03D108E0] AC EOB marker is absent pos=64
    Last message repeated 2 times
    Last message repeated 2 times
[dvvideo @ 03D108E0] AC EOB marker is absent pos=67
[dvvideo @ 03D108E0] AC EOB marker is absent pos=69
[dvvideo @ 03D108E0] AC EOB marker is absent pos=64
    Last message repeated 1 times

...>ffmpeg -v error -i file2.avi -f null -
[dvvideo @ 03C108E0] AC EOB marker is absent pos=64
    Last message repeated 2 times
    Last message repeated 3 times
[dvvideo @ 03C108E0] AC EOB marker is absent pos=67
[dvvideo @ 03C108E0] AC EOB marker is absent pos=69
[dvvideo @ 03C108E0] AC EOB marker is absent pos=64
    Last message repeated 1 times

Note that the actual difference is at offset 3759b86f - not sure how that relates to ffmpeg locations but it seems to be well after them. On a side note, every time I run ffmpeg on the same file it reports different locations

EDIT 2 with more detail (-v verbose) ffmpeg reports that the error is at 00:26:11.64. The entire video is 00:33:33.17 and the one bit difference at ~12% of the length of the file. With CBR that would be at ~ minute 4.

Answer 1

OK... Found it. File 2 is better :) Here's how I did it.

1. I used ffmpeg to extract raw audio from both files and compared them. They were equal.
2. Then I extracted raw video from both files and compared those. They were different in that one bit.
3. Knowing that the difference is at approx. minute 4, I extracted all frames from minute 3 to minute 5 of videos as individual frames (uncompressed format to make sure I maintain the difference). One frame at ~4:05 was different.
4. The difference was almost invisible to the naked eye - had to compare the two frames in Photoshop first to see where it is before I could see what it was - a very slight green overcast in a small area.
5. Picked the file that does not have that green overcast as better :)