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• 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

• How create with ffmpeg a *.mov file which could be opened in default WMP ?

  22 mai 2016, par xiaose

  How create MOV, QuickTime Movie (.mov) which could be opened in default Windows Media Player ? Actually, smth. like this : http://cdn.online-convert.com/example-file/video/mov/example.mov

  I have files MPEG-1 or MPEG-2 and want to convert it with ffmpeg to the mov. Sure, I can write smth. like this :

  ffmpeg -i in.mpg -level 3.1 -vformat mpeg4 -qscale 1 -f mov out.mov

  ...and this will be Ok. But I need resulting file which will be correct MOV but, may be, without mpeg4 in it and played in WMP without installing any additional codecs

• How to avoid that Mediafilesegmenter cuts the last frames ?

  26 avril 2021, par Alexander Khitev

  We use ffmpeg and mediafilesegmenter for creating HLS video, we also created shell script for convenience. I noticed one issue that if we use original video with float duration, for example 10.602 seconds mediafilesegmenter cuts some last frames. How can I fix it ? Or what other tools can I use to create HLS ? Thanks !

  


  ffmpeg -i movie.mp4 -vb 500K movie-500K.mp4
ffmpeg -i movie.mp4 -vb 1500K movie-1500K.mp4

mkdir small
mkdir big

mediafilesegmenter -f small -A -B segment -t 1 movie-500K.mp4
mediafilesegmenter -f big -A -B segment -t 1 movie-1500K.mp4
mv movie-500K.plist small/movie-500K.plist
mv movie-1500K.plist big/movie-1500K.plist

variantplaylistcreator -r -o prog_index.m3u8 small/prog_index.m3u8 small/movie-500K.plist big/prog_index.m3u8 big/movie-1500K.plist