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• riscv : probe for Zbb extension at load time

  8 juin 2024, par Rémi Denis-Courmont

  riscv : probe for Zbb extension at load time
  Due to hysterical raisins, most RISC-V Linux distributions target a
  
  RV64GC baseline excluding the Bit-manipulation ISA extensions, most
  
  notably :
  
   Zba : address generation extension and
  
   Zbb : basic bit manipulation extension.
  
  Most CPUs that would make sense to run FFmpeg on support Zba and Zbb
  
  (including the current FATE runner), so it makes sense to optimise for
  
  them. In fact a large chunk of existing assembler optimisations relies
  
  on Zba and/or Zbb.
  Since we cannot patch shared library code, the next best thing is to
  
  carry a flag initialised at load-time and check it on need basis.
  
  This results in 3 instructions overhead on isolated use, e.g. :
  
  1 :  AUIPC rd, %pcrel_hi(ff_rv_zbb_supported)
  
      LBU   rd, %pcrel_lo(1b)(rd)
  
      BEQZ  rd, non_Zbb_fallback_code
  
      // Zbb code here
  The C compiler will typically load the flag ahead of time to reducing
  
  latency, and can also keep it around if Zbb is used multiple times in a
  
  single optimisation scope. For this to work, the flag symbol must be
  
  hidden ; otherwise the optimisation degrades with a GOT look-up to
  
  support interposition :
  
  1 :  AUIPC rd, GOT_OFFSET_HI
  
      LD    rd, GOT_OFFSET_LO(rd)
  
      LBU   rd, (rd)
  
      BEQZ  rd, non_Zbb_fallback_code
  
      // Zbb code here
  This patch adds code to provision the flag in libraries using bit
  
  manipulation functions from libavutil : byte-swap, bit-weight and
  
  counting leading or trailing zeroes.
  

  • [DH] libavcodec/riscv/Makefile
  • [DH] libavcodec/riscv/cpu_common.c
  • [DH] libavdevice/riscv/Makefile
  • [DH] libavdevice/riscv/cpu_common.c
  • [DH] libavfilter/riscv/Makefile
  • [DH] libavfilter/riscv/cpu_common.c
  • [DH] libavformat/riscv/Makefile
  • [DH] libavformat/riscv/cpu_common.c
  • [DH] libavutil/riscv/Makefile
  • [DH] libavutil/riscv/cpu.h
  • [DH] libavutil/riscv/cpu_common.c
  • [DH] libswscale/riscv/Makefile
  • [DH] libswscale/riscv/cpu_common.c
  • [DH] tests/ref/fate/source

• Merge commit ’e481458bc308ee838deaeacac51929514762e7a7’

  26 avril 2016, par Derek Buitenhuis

  Merge commit ’e481458bc308ee838deaeacac51929514762e7a7’
  * commit ’e481458bc308ee838deaeacac51929514762e7a7’ :
  
    h264 : factor out pred weight table parsing into a separate file
  Merged-by : Derek Buitenhuis <derek.buitenhuis@gmail.com>
  

  • [DH] libavcodec/Makefile
  • [DH] libavcodec/dxva2_h264.c
  • [DH] libavcodec/h264.c
  • [DH] libavcodec/h264.h
  • [DH] libavcodec/h264_mb.c
  • [DH] libavcodec/h264_mc_template.c
  • [DH] libavcodec/h264_parse.c
  • [DH] libavcodec/h264_parse.h
  • [DH] libavcodec/h264_parser.c
  • [DH] libavcodec/h264_refs.c
  • [DH] libavcodec/h264_slice.c
  • [DH] libavcodec/vaapi_h264.c

• Ubuntu reduce video size with ffmepg and change format

  27 juillet 2015, par Arnas Pečelis

  I want to watermark, reduce weigth, resize and change format for selected videos.
  Also I need to keep quality as high as it possible.

  Now what I have :

  ffmpeg -i prepared/video.mp4 -i units/video_watermark.png -filter_complex overlay=10:10 -codec:a copy moved/video_test.mp4

  and I’m watermarking video, but the quality drops a lot. Also I have :

  ffmpeg -i prepared/video.mp4 -s 1280x720 -b 512k -vcodec mpeg1video -acodec copy

  but also I need to reduce weight also as lot as possible. The reconstructed videos will be shown as movies online. My question would be - is it possible to do it one line and change format to .mp4 ?

  PS. I have constructed command :

  ffmpeg -i downloaded/movie/movie.avi -c:v libx264 -acodec libfaac -b:a 64k -preset ultrafast -vf "movie=units/video_watermark.png [watermark]; [in][watermark] overlay=10:10 [out]" -movflags faststart prepared/movie.mp4

  but it returns me error :

  ffmpeg version 2.7.1 Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04)
  
    configuration:
  
    libavutil      54. 27.100 / 54. 27.100
  
    libavcodec     56. 41.100 / 56. 41.100
  
    libavformat    56. 36.100 / 56. 36.100
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 16.101 /  5. 16.101
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.100 /  1.  2.100
  
  Unrecognized option 'preset'.
  
  Error splitting the argument list: Option not found