Recherche avancée

Sur d’autres sites (3886)

• 1080p video on Beagle

  10 février 2010, par Mans — Multimedia

  FOSDEM 2010 is over, and I’d like to call it a success for FFmpeg. The 11-man strong delegation showed the stunned audience a smashing demo featuring a Beagle-powered video wall. It looked like this :

  The people who pulled this off look like this :

  

• lavc/opusdsp : RISC-V V (512-bit) postfilter

  5 octobre 2022, par Rémi Denis-Courmont

  lavc/opusdsp : RISC-V V (512-bit) postfilter
  This adds a variant of the postfilter for use with 512-bit vectors.
  
  Half a vector is enough to perform the scalar product. Normally a whole
  
  vector would be used anyhow. Indeed fractional multiplers are no faster
  
  than the unit multipler.
  But in this particular function, a full vector makes up 16 samples,
  
  which would be loaded at each iteration of the outer loop. The minimum
  
  guaranteed CELT postfilter period is only 15. Accounting for the edges,
  
  we can only safely preload up to 13 samples.
  The fractional multipler is thus used to cap the selected vector length
  
  to a safe value of 8 elements or 256 bits.
  Likewise, we have the 1024-bit variant with the quarter multipler. In
  
  theory, a 2048-bit one would be possible with the eigth multipler, but
  
  that length is not even defined in the specifications as of yet, nor is
  
  it supported by any emulator - forget actual hardware.
  

  • [DH] libavcodec/riscv/opusdsp_init.c
  • [DH] libavcodec/riscv/opusdsp_rvv.S

• avfilter/formats : Make check for buffer overflow redundant

  13 août 2020, par Andreas Rheinhardt

  avfilter/formats : Make check for buffer overflow redundant
  and remove the redundant check.
  This check for whether the allocated buffer is sufficient has been added
  
  in commit 1cbf7fb4345a3e5b7791d483241bf4759bde4ece (merging commit
  
  5775a1832c4165e6acc1d307004b38701bb463f4). It is not sufficient to
  
  detect invalid input lists (namely lists with duplicates) ; its only use
  
  is to avoid buffer overflows. And this can be achieved by simpler means :
  
  Make sure that one allocates space for so many elements as the outer loop
  
  ranges over and break out of the inner loop if a match has been found.
  
  For valid input without duplicates, no further match will be found anyway.
  This change will temporarily make the allocated formats array larger
  
  than before and larger than necessary ; this will be fixed in a later
  
  commit that avoids the allocation altogether.
  If a check for duplicates in the lists is deemed necessary, it should be
  
  done properly somewhere else.
  Finally, the error message that is removed in this commit used
  
  __FUNCTION__, which is a GCC extension (C99 added __func__ for this).
  
  So this commit removes a warning when compiling in -pedantic mode.
  Reviewed-by : Nicolas George <george@nsup.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavfilter/formats.c