[Mp4-tech] Synchronizing MP4 files from multiple sources

[bobsadur aol.com]

I've got several video recorders recording MP4 at the same time.? I have an accurate common clock going to each recorder, so the access unit durations should be consistent between recordings.? What I don't control is the record button on each recorder.? They can be pressed at different times, and in some cases a recording will be made on one recorder but not the others.? Where there is overlap, though, I want to show the video synchronized on the same display.? Any advice about how to set this up?? I thought of having an OCR stream in each file, but I read that it's uncommon to use that with stored files, as it's meant to correct for network delays.? I've thought of creating another file with a BIFS stream that refers to the separate recordings, introducing each one as data is available.? Any other suggestions?
Bob Sadur
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Sent: Mon, 14 Jan 2024 12:07 pm
Subject: Mp4-tech Digest, Vol 54, Issue 4
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Today's Topics:
   1. question about mb_in_video_packet (Matthew)
   2. Corresponding block predictor in Reference frame in JM    12.2
      ME Algorithms (Peace)
----------------------------------------------------------------------
Message: 1
Date: Sun, 13 Jan 2024 17:26:00 -0800
From: "Matthew" <kingshine.matthew gmail.com>
Subject: [Mp4-tech] question about mb_in_video_packet
To: <Mp4-tech lists.mpegif.org>
Message-ID: <003a01c8564c$7519afa0$d332a8c0 MatthewWang>
Content-Type: text/plain; charset="iso-8859-1"
Hi, Dear all
In the MPEG-4 video syntax, "data_partitioned_i_vop"
There is a element "mb_in_video_packet", I don't know where this element can be 
obtained,
Is it in the system syntax or I can't compute it through other syntax elelments.
Thanks
Matthew
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Message: 2
Date: Mon, 14 Jan 2024 18:11:41 +0900
From: Peace <humaira.nisar gmail.com>
Subject: [Mp4-tech] Corresponding block predictor in Reference frame
    in JM   12.2 ME Algorithms
To: mp4-tech lists.mpegif.org
Message-ID:
    <139c4c630801140111l350336b3x9d7920c930e285f6 mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi,
I am looking for the predictor of the block that is located at the same
p[osition in the previous frame.
IN ME-umhex.c , i have found this....
//prediction using mV of last ref moiton vector
  if(pred_MV_ref_flag == 1)      //Notes: for interlace case, ref==1 should
be added
  {
    cand_x = pic_pix_x + (pred_MV_ref[0]/4);
    cand_y = pic_pix_y + (pred_MV_ref[1]/4);
    SEARCH_ONE_PIXEL
  }
However in Me-EPZS.c , i am unable to find this one, Probably there it does
not exists, as all the other temporal predictors are  present.
If yes then can anyone point out?
Thanks and Best REgards
Humaira
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