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• Closed Captioned TS to Open Captioned MP4 (w/Accurate Positioning)

  19 décembre 2019, par Cody Greene

  I am attempting to convert closed captioned MPEG TS files to open captioned MP4s using ffmpeg.

  I am having trouble retaining the positioning of the captions.

  The closest I’ve gotten is with this simple script :

  ffmpeg -f lavfi -i movie=input.ts[out+subcc] -map 0:1 output.ass
  
  ffmpeg -i input.ts -vf "subtitles=output.ass" -c:v libx264 -pix_fmt yuv420p -b:v 8000k -c:a aac -b:a 192k target.mp4

  The result of this is the open captions are shifted FAR left and the bounding box draws black over the empty spaces left of wherever text is centered (ssa adds "/h", easily removed with sed, but then it’s left-aligned captions only)

  However, the vertical position, overall size, etc. all look great.

  Most subtitle formats force everything to the bottom center, but I’m trying to mimic the look of an open caption on the mp4 output.

  I’ve tried several formats with ccextractor and ffmpeg, but no luck. Any ideas what I’m doing wrong ?

• Revision 8cb09719a3 : vpxenc : open output file after setting pass # write_ivf_file_header would incor

  15 août 2013, par James Zern

  Changed Paths :
   Modify /vpxenc.c

  
  
  vpxenc : open output file after setting pass #

  write_ivf_file_header would incorrectly skip writing the file header in
  the 2nd pass, causing the initial frame header to be overwritten on
  close potential causing an overly large frame header to be read and a
  crash.

  most likely broken since :
  9e50ed7 vpxenc : initial implementation of multistream support

  fixes issue #585

  Change-Id : I7e863e295dd6344c33b3e9c07f9f0394ec496e7b

• Streaming video from nodejs to an open player

  27 août 2013, par Matthew Young

  Odd ball question for somebody just getting started with html5 players and streaming video....

  When using YouTube long videos can be scrolled towards then end then played from there. Assuming YouTube first pulls down metadata like total video start/stop points and a bunch of thumbnails for scrolling.

  Is this possible with an open html5 video player (like projekkter) ? Reason asking is that I have video data inside a mongo database that I would like to stream similar to the YouTube player.

  Inside mongo I have a bunch of smaller h264 files each in a document : actual raw h264 usually 1000kb (max 2 seconds), creation timestamp (long), and potentially a converted format (like mp4) for known clients. Idea is to query off a time range and order by creation time then piping the results into readable stream. There is a nice ffmpeg module to take streams and reformat if needed. Thought about piping the stream to the client with binaryjs and appending it into the player.

  But the source directives in the documentation are usually URLs plus I need to lock down the start/stop point for the total video being played plus thumbnails.