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• avcodec/dvdsubdec, dvbsubdec : remove bitmap dumping in DEBUG builds

  28 mai 2022, par softworkz

  avcodec/dvdsubdec, dvbsubdec : remove bitmap dumping in DEBUG builds
  It's been a regular annoyance and often undesired.
  
  There will be a subtitle filter which allows to dump individual
  
  subtitle bitmaps.
  Signed-off-by : softworkz <softworkz@hotmail.com>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavcodec/dvbsubdec.c
  • [DH] libavcodec/dvdsubdec.c

• How to concatenate .mp4 files into one 4x4 movie using -ffmpeg- ?

  7 août 2021, par Clive Nicholas

  How should I best concatenate 16 separate .mp4 files into one 4x4 movie using -ffmpeg- ?

  


  I have workable code to create 2x2 movies (with changeable optional flag calls), with four equally-sized files, thus :

  


  ffmpeg -i foo1.mp4 -i foo2.mp4 -i foo3.mp4 -i foo4.mp4 \ 
 -filter_complex \
   "[0:v][1:v]hstack[t]; \
    [2:v][3:v]hstack[b]; \
    [t][b]vstack,format=yuv420p[v]; \
    [0:a][1:a][2:a][3:a]amerge=inputs=4[a]" \
-map "[v]" \ 
-map "[a]" \
-ac 2 -c:v libx264 \
foo.mp4


  


  and with four unequally-sized files, thus :

  


  ffmpeg -i foo1.mp4 -i foo2.mp4 -i foo3.mp4 -i foo4.mp4 \
 -filter_complex \
   "[0:v]scale=640:360[v0]; \
    [1:v]scale=640:360[v1]; \
    [2:v]scale=640:360[v2]; \
    [3:v]scale=640:360[v3]; \
    [v0][v1]hstack[t]; \
    [v2][v3]hstack[b]; \
    [t][b]vstack,format=yuv420p[v]; \
    [0:a][1:a][2:a][3:a]amerge=inputs=4[a]" \
-map "[v]" \
-map "[a]" \
-c:v libx264 -crf 23 \
-c:a aac -b:a 192k \
foo.mp4


  


  There is a solution posted here for splitting a single movie file into 16 4x4 pieces, but naturally I want to do the opposite ! I can't quite work out in my own mind how I can knit together the necessary elements from my 2x2 code routines and the 4x4 split code into a satisfactory 4x4 solution. It may well be that the 16 individual movie files each have to be re-scaled downwards.

  


  Any ideas would be gratefully received, especially coding solutions which are readily tweakable to any matrix combination (e.g., 3x3, 5x5, etc).

  


  Thanks very much, Clive

  


• Issue with creating Video files from Binary files

  22 septembre 2022, par user20057686

  We have a bunch of binary files that represent Video data.
This is how the binary files were created :

  


  

  1. Used MediaRecorder from a React application to capture the browser window.
To capture the screen stream we used (Navigator.)MediaDevices.getDisplayMedia() API

  


  2. Each video is recorded for 1-second duration

  


  3. This data is then encoded with base64 and sent through a websocket. The server decodes the base64 string and stores the binary data in a file (without any extension)

  


  


  So we now have a bunch of binary files each containing 1 second worth of video data.

  


  The issue is, we are not able to convert all the binary files back to a single video.

  


  


  1. We tried using ffmpeg

     


     copy /b * merged.

     


     ffmpeg -i merged merged.mp4

     


  


  


  Basically first merging all the binary files and converting to mp4. It didn't work. The resulting video duration is not equal to the (number_of_files) in seconds.

  


  


  2. We also tried converting individual chunks with ffmpeg but we get the below error :

     


     [h264 @ 000001522dc74b80] [error] non-existing PPS 0 referenced
[h264 @ 000001522dc74b80] [error] non-existing PPS 0 referenced
[h264 @ 000001522dc74b80] [error] decode_slice_header error
[h264 @ 000001522dc74b80] [error] no frame !
I can provide the complete logs if needed.

     


  


  3. Next thing we tried was to use MoviePy library in Python. We programmatically concatenated the files and saved them as WebM and imported it into MoviePy as a Video.

     


  


  


  In all the above approaches, we couldn't get the full video.