[FFmpeg-user] comparison of apparently same media files …

[Albretch Mueller]

if you use youtube-dl and for the naming use just the URI or the name
given in the verbal description of the file the files contents differ
even though their lengths are the same and they "look" the same even
if you download the files one right after the other (they don't use
tildes ("~") in youtube URIs):

export _YT_URI=qkSuYoexbiY
echo ${_YT_URI}

date
youtube-dl --no-overwrites --continue --no-progress --audio-format
best --max-quality mp4 -o
'%(uploader)s'"/"'%(stitle)s'"~"${_YT_URI}.'%(ext)s'
"http://www.youtube.com/watch?v=${_YT_URI}&hd=1"
date
youtube-dl --no-overwrites --continue --no-progress --audio-format
best --max-quality mp4 -o '%(uploader)s'"/"${_YT_URI}.'%(ext)s'
"http://www.youtube.com/watch?v=${_YT_URI}&hd=1"
date

$ ls -lR
.:
total 4
drwxr-xr-x 2 knoppix knoppix 4096 Aug 29 12:03 TheYoungTurks

./TheYoungTurks:
total 260528
-rw-r--r-- 1 knoppix knoppix 133389811 Jun  4 23:31
Bradley_Manning_Trial_Update~qkSuYoexbiY.mp4
-rw-r--r-- 1 knoppix knoppix 133389811 Jun  4 23:31 qkSuYoexbiY.mp4

$ md5sum -b TheYoungTurks/Bradley_Manning_Trial_Update~qkSuYoexbiY.mp4
d7c2064ee789dd79395da15ab2bcd1b2
*TheYoungTurks/Bradley_Manning_Trial_Update~qkSuYoexbiY.mp4

$ md5sum -b TheYoungTurks/qkSuYoexbiY.mp4
d7a5937fda4ad2d8819e97e1c041b29b *TheYoungTurks/qkSuYoexbiY.mp4

 Is there a way to use ffmpeg to see what is different in the files,
and if the difference lies in some metadata or it is just some other
kind of corruption?

 What do you think is going on here?

 thanks
 lbrtchx