[FFmpeg-user] Unresolved concatenation and subtitle problems

[Mark Filipak]

On 12/28/23 07:47, Nicolas Gaullier wrote:
>> When ffmpeg's '-vf showinfo' and ffprobe's '-show_streams' disagree, which should I trust?
> 
> You should usually trust both, but their meanings are different.

You should trust neither.

I have more info that includes corrections to what I previously wrote -- gad, this is confusing and 
error prone work.

COMPUTE (exact)
     MPV     <------1:18:19.236208[3..]-----> end to end
             0..4699.1945 seconds, first..last
             0..112668 frames, computed from seconds
             :
SHOWINFO    0..112668 frames
             0..422927505 ticks <-----------+
FRAMECRC    1044806..423972311 ticks  vid  ¦
             :\________\__ 422927505 <------+
             1048560..423979440 ticks  aud
             :\________\__ 422930880
  STREAMS    1048560..?    vid start_pts <- not in showinfo, not vid PTS
             1048560..?    aud start_pts
              \ 3143152..? sub start_pts
               \_\__ 1st sub at 0:23.273 - confirmed.

if -framecrc is right, then
-showinfo "n:   0 pts:      0" <- wrong -- no equivocation, wrong
-show_streams vid "start_pts=1048560" <- wrong -- no equivocation, wrong

I previously wrote, "So '-framecrc' & '-showinfo' agree but they disagree with '-show_streams'." 
That was erroneous. They all disagree with each other. Apparently, ffmpeg/ffprobe should be fixed so 
that my chart would then be:

     MPV     <------1:18:19.236208[3..]-----> end to end
             0..4699.1945 seconds, first..last
             0..112668 frames, computed from seconds
             :
SHOWINFO    0..112668 frames
             1044806..423972311 ticks      <== when fixed
FRAMECRC    1044806..423972311 ticks  vid
             :\________\__ 422927505
             1048560..423979440 ticks  aud
             :\________\__ 422930880
  STREAMS    1044806..?    vid start_pts   <== when fixed
             1048560..?    aud start_pts
              \ 3143152..? sub start_pts
               \_\__ 1st sub at 0:23.273 - confirmed.

But is '-framecrc' actually correct?
I will use the '-framecrc' numbers to do the DTS-PTS shifting and packet concatenations and will 
report back.

-- Mark.