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• Problems with muxing fmp4 stream with libav

  20 juillet 2020, par Elias Wagnerberger

  currently i have an application that is supposed to send fragmented mp4 data over a websocket to a client for it to be played there.

  


  i have a working implementation that pipes the raw frames to a spawned ffmpeg process and then reads fragmented mp4 segments from the output pipe before it sends those on to the client where the client then displays the video correctly.

  


  my problem is that when i try to make an implementation using libav it doesnt seem to work. my libav config uses libx264rgb to encode the frames before muxing them to a mp4, but when i try to play the provided segments in a browser using MSE it spits out an error. after having checked chrome ://media-internals i have figured out that the problem lies in the moov box that is one of the two initialization boxes of a fmp4 stream.

  


  chrome apparently has a problem with parsing that box when its sent from libav, but not when its sent from ffmpeg.

  


  my question is :
What is the correct muxer configuration of libav so that it creates a fragmented mp4 stream where the client can recieve media boxes from the middle, after having been provided the init boxes ?

  


• omxplayer - Seamless looping of a directory

  18 août 2021, par delk1ch

  I'm trying to make a script/program that will seamlessly loop through all video files in a directory using omxplayer. So far my best solution was using ffmpeg to concat the videos of the directory and loop the output using omxplayer —loop output, but I've kept running into issues with different framerates and codecs of videos and the concating itself takes way longer than I can afford. Does anyone have a clue or a snippet on how digital signage software solutions loop their videos ?

  


• checkasm : Generalize crash handling

  14 décembre 2023, par Martin Storsjö

  checkasm : Generalize crash handling
  This replaces the riscv specific handling from
  
  7212466e735aa187d82f51dadbce957fe3da77f0 (which essentially is
  
  reverted), with a different implementation of the same (plus a bit
  
  more), based on the corresponding feature in dav1d's checkasm,
  
  supporting both Unix and Windows.
  See in particular the dav1d commits
  
  0b6ee30eab2400e4f85b735ad29a68a842c34e21,
  
  0421f787ea592fd2cc74c887f20b8dc31393788b,
  
  8501a4b20135f93a4c3b426468e2240e872949c5 and
  
  d23e87f7aee26ddcf5f7a2e185112031477599a7, authored by Henrik Gramner.
  The overall approach compared to the existing implementation for
  
  riscv is the same ; set up a signal handler, store the state with
  
  sigsetjmp, jump out of the crashing function with siglongjmp.
  The main difference is in what happens when the signal handler
  
  is invoked. In the previous implementation, it would resume from
  
  right before calling the crashing function, and then skip that call
  
  based on the setjmp return value.
  In the imported implementation from dav1d, we return to right before
  
  the check_func() call, which will skip testing the current function
  
  (as the pointer is the same as it was before).
  Other differences are :
  
   Support for other signal handling mechanisms (Windows
  
    AddVectoredExceptionHandler)
  
   Using RtlCaptureContext/RtlRestoreContext instead of setjmp/longjmp
  
    on Windows with SEH
  
   Only catching signals once per function - if more than one
  
    signal is delivered before signal handling is reenabled, any
  
    signal is handled as it would without our handler
  
   Not using an arch specific signal handler written in assembly
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tests/checkasm/checkasm.c
  • [DH] tests/checkasm/checkasm.h
  • [DH] tests/checkasm/riscv/checkasm.S