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• Concatenating video clip with static image causes buffer errors

  16 février 2020, par jgaeb

  I’m trying to concatenate a 15 second clip of a video (MOVIE.mp4) with 5 seconds (no audio) of an image (IMAGE.jpg) using FFmpeg.

  Something seems to be wrong with my filtergraph, although I’m unable to determine what. The command I’ve put together is the following :

  ffmpeg \
  
  -loop 1 -t 5 -I IMAGE.jpg \
  
  -t 15 -I MOVIE.mp4 \
  
  -filter_complex "[0:v]scale=480:640[1_v];anullsrc[1_a];[1:v][1:a][1_v][1_a]concat=n=2:v=1:a=1[out]" \
  
  -map "[out]" \
  
  -strict experimental tst_full.mp4

  Unfortunately, this seems to be creating some strange results :

  1. On my personal computer (FFmpeg 4.2.1) it correctly concatenates the movie with the static image ; however, the static image lasts for an unbounded length of time. (After entering ctrl-C, the movie is still viewable, but is of an extremely long length—e.g., 35 min—depending on when I interrupt the process.)

  2. On a remote machine where I need to do the ultimate video processing (FFmpeg 2.8.15-0ubuntu0.16.04.1), the command does not terminate, and instead, I get cascading errors of the following form :

  Past duration 0.611458 too large
  
  ...
  
  [output stream 0:0 @ 0x21135a0] 100 buffers queued in output stream 0:0, something may be wrong.
  
  ...
  
  [output stream 0:0 @ 0x21135a0] 100000 buffers queued in output stream 0:0, something may be wrong.

  I haven’t been able to find much documentation that elucidates what these errors mean, so I don’t know what’s going wrong.

• FFmpeg truncates untrunc'ed video

  18 mars 2020, par petrpulc

  Background : Colleague's Panasonic consumer camera had issues with high-capacity SD card and yielded two different types of truncated files (mp4 and mdt) with both header and index corrupted. Both were "fixable" with following steps :

  



  

  1. Locate with hex editor the ascii sequence "mdat" in both a truncated and a corresponding known good file. In mp4 the "mdat" is quite deep in the file as it contains some (but bad) headers, the mdt type almost starts with it.

  


  2. Replace everything up to the "mdat" sequence with known good header. BUT this also means that metadata on length are copied over.

  


  3. Run https://github.com/ponchio/untrunc on the file with corrected header (it refused to run on original files).

  


  4. Profit ! VLC plays the file fine, ffprobe shows correct length. BUT ffmpeg encoding stops at the end timecode of the file I taken the known good header from in step 2.

  


  5. A somewhat ugly solution is to recode the file in VLC (video copy seems to be breaking file up again).

  


  



  I am wondering if I overlooked something ; big time. I guess I do, but simple timecode operations on input file do not seem to have any effect at all.

  



  Is there a way to persuade ffmpeg to encode the whole file that ffprobe and VLC see ?

  



  Files may be provided for analysis on personal basis only, sorry.

  


• Different results between windows and Linux in opencv c++

  24 mars 2020, par Samer

  I have tried this opencv and ffmpeg C++ code to demux a video and edit it and mux it back again but it doesn’t seem to work properly on windows (using Visual Studio)

  the problem occurs by skipping some frames especially at the end of the video and increasing the video output size not on all windows PCs. We have tried it on a 35 MB video and when we did the editing the output video size was 2.8GB on some windows PCs and the last frames skipped (the problem) and some other PCs the output video size was 500MB and there were no skipped frames (all fine).

  so the question is, why would the same code with the same build and windows versions behave differently and produce problems on some Pcs ?

  (we also did it on linux ubuntu and macos and it was working fine on different PCs)

  https://github.com/WajdiMuh/parallelalgo for the files

  https://gjuedujo-my.sharepoint.com/personal/m_albizreh1_gju_edu_jo/_layouts/15/onedrive.aspx?id=%2Fpersonal%2Fm%5Falbizreh1%5Fgju%5Fedu%5Fjo%2FDocuments%2FParallel%20Project%2Fbinr&originalPath=aHR0cHM6Ly9nanVlZHVqby1teS5zaGFyZXBvaW50LmNvbS86ZjovZy9wZXJzb25hbC9tX2FsYml6cmVoMV9nanVfZWR1X2pvL0VzaHFWNDJCVThkQ25KOFV0dm82NHJNQmdoOWdCeEZOblkwQWtRMkQ0MU5UV3c_cnRpbWU9TTl4Zi1YblAxMGc for the release version (vidd.MP4 is the video)

  Thanks in Advance