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• mp4 video doesn't play on mobile, but it plays locally [closed]

  20 août 2023, par Simon

  I built a mp4 video from jpg images using this command :

  


  ffmpeg -framerate 1 -i img%d.jpg -c:v libx264 -pix_fmt yuv420p -r 1 output.mp4


  


  I can open and play video on my computer (in VLC and in a browser), but I can't play it on mobile (Chrome on Android). There's an info about duration, I can press the "play" button, but the video doesn't play at all.

  


  How to fix that ?

  


• avcodec/movtextenc : Simplify writing to AVBPrint

  15 octobre 2020, par Andreas Rheinhardt

  avcodec/movtextenc : Simplify writing to AVBPrint
  The mov_text encoder uses an AVBPrint to assemble the subtitles ;
  
  yet mov_text subtitles are not pure text ; they also have a binary
  
  portion that was mostly handled as follows :
      uint32_t size = /* calculation */ ;
  
      size = AV_RB32(&size) ;
  
      av_bprint_append_data(bprint, (const char*)&size, 4) ;
  Here AV_RB32() is a no-op on big-endian systems and a LE-BE swap
  
  on little-endian systems, making the output endian-independent.
  Yet this is ugly and unclean : On LE systems, the variable size from
  
  the snippet above won't contain the correct value any more. Furthermore,
  
  using this pattern leads to lots of small writes to the AVBPrint.
  This commit therefore changes this to using a temporary buffer instead :
      uint8_t buf[4] ;
  
      AV_WB32(buf, /* size calculation */) ;
  
      av_bprint_append_data(bprint, buf, 4) ;
  This method also allows to use bigger buffers holding more than one
  
  element, saving calls to av_bprint_append_data() and reducing codesize.
  Reviewed-by : Philip Langdale <philipl@overt.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/movtextenc.c

• FFMPEG output to multiple rtmp and synchronize them

  26 mai 2020, par voncount

  presume I have a video, and I use filter to crop them let say 1/2 and 1/2 width to 2 rtmp output streams.

  



  Now 2 clients will subscribe to these stream let say

  



  vlc1 - stream 1 | vlc2 - stream 2

  



  how can I synchronize them to play at the same time (I always see 1 client play faster or slower than other)

  



  Here is the code

  



  ffmpeg -re -stream_loop -1 -i sample.mp4 \
  -filter:v "crop=in_w/2:in_h:0:0" -c:a copy -f flv rtmp://localhost/live/1 \
  -filter:v "crop=in_w/2:in_h:in_w/2:0" -c:a copy -f flv rtmp://localhost/live/2


  



  Gotcha1

  



  Found out the problem was stream_loop and with each iteration and filter it produces some delay.

  



  From now, the only solution works for me is

  



  

  1. Playing the original file (with loop) and output to a rtmp stream

  


  2. Create 2 stream that read the origin stream, do cropping and then output 2 rtmp streams

  


  



  ffmpeg -i rtmp://localhost/live/feed -filter:v crop=in_w/2:in_h:0:0 -c:a copy -f flv rtmp://localhost/live/1

ffmpeg -i rtmp://localhost/live/feed -filter:v crop=in_w/2:in_h:in_w/2:0 -c:a copy -f flv rtmp://localhost/live/2