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• libavutil : add an FFT & MDCT implementation

  2 mai 2019, par Lynne

  libavutil : add an FFT & MDCT implementation
  This commit adds a new API to libavutil to allow for arbitrary transformations
  
  on various types of data.
  
  This is a partly new implementation, with the power of two transforms taken
  
  from libavcodec/fft_template, the 5 and 15-point FFT taken from mdct15, while
  
  the 3-point FFT was written from scratch.
  
  The (i)mdct folding code is taken from mdct15 as well, as the mdct_template
  
  code was somewhat old, messy and not easy to separate.
  A notable feature of this implementation is that it allows for 3xM and 5xM
  
  based transforms, where M is a power of two, e.g. 384, 640, 768, 1280, etc.
  
  AC-4 uses 3xM transforms while Siren uses 5xM transforms, so the code will
  
  allow for decoding of such streams.
  
  A non-exaustive list of supported sizes :
  
  4, 8, 12, 16, 20, 24, 32, 40, 48, 60, 64, 80, 96, 120, 128, 160, 192, 240,
  
  256, 320, 384, 480, 512, 640, 768, 960, 1024, 1280, 1536, 1920, 2048, 2560...
  The API was designed such that it allows for not only 1D transforms but also
  
  2D transforms of certain block sizes. This was partly on accident as the stride
  
  argument is required for Opus MDCTs, but can be used in the context of a 2D
  
  transform as well.
  
  Also, various data types would be implemented eventually as well, such as
  
  "double" and "int32_t".
  Some performance comparisons with libfftw3f (SIMD disabled for both) :
  
  120 :
  
    22353 decicycles in     fftwf_execute,     1024 runs,      0 skips
  
    21836 decicycles in compound_fft_15x8,     1024 runs,      0 skips
  128 :
  
    22003 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
    23132 decicycles in monolithic_fft_ptwo,   1024 runs,      0 skips
  384 :
  
    75939 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
    73973 decicycles in compound_fft_3x128,    1024 runs,      0 skips
  640 :
  
   104354 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
   149518 decicycles in compound_fft_5x128,    1024 runs,      0 skips
  768 :
  
   109323 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
   164096 decicycles in compound_fft_3x256,    1024 runs,      0 skips
  960 :
  
   186210 decicycles in      fftwf_execute,    1024 runs,      0 skips
  
   215256 decicycles in compound_fft_15x64,    1024 runs,      0 skips
  1024 :
  
   163464 decicycles in       fftwf_execute,   1024 runs,      0 skips
  
   199686 decicycles in monolithic_fft_ptwo,   1024 runs,      0 skips
  With SIMD we should be faster than fftw for 15xM transforms as our fft15 SIMD
  
  is around 2x faster than theirs, even if our ptwo SIMD is slightly slower.
  The goal is to remove the libavcodec/mdct15 code and deprecate the
  
  libavcodec/avfft interface once aarch64 and x86 SIMD code has been ported.
  
  New code throughout the project should use this API.
  The implementation passes fate when used in Opus, AAC and Vorbis, and the output
  
  is identical with ATRAC9 as well.
  

  • [DH] libavutil/Makefile
  • [DH] libavutil/tx.c
  • [DH] libavutil/tx.h

• Connect FFServer multiple instances

  3 mars 2020, par absentio

  I am trying to deploy FFServer on Kubernetes and try to use the power of distributed systems.
  It’s the first time I am using both and so I am a bit confused.
  Got my Kubernetes setup working on my bare metal server, LoadBalancer and CNI are working flawlessly. I then created an FFServer deployment and a FFServer service. Then I made an NFS storage to share ffserver.conf and feed files, but there is something strange happening.

  All my ffserver k8s pods load the ffserver.conf file with not problem, then when I start to stream using ffmpeg the loadbalancer gives my stream to one of my server(i’ll call it pod1). The problem is that I can get the stream played if connecting directly to pod1 but will not work if i try to get it from pod2 although pod2 could read the feed.ffm written from pod1.

  NFS storage is setup with ReadWriteMany. How could I get it to work ? Is there any way to use multiple ffserver without having to ffmpeg to all of them one by one ?

• How to identify exact type or variation of a .mp4 file

  5 octobre 2017, par Dave502619

  Can anyone tell me if there are different variations of mp4 file and if so, how to identify the exact type or variation of a mp4 file ?

  The reason I need to know this is if I pass an .mp4 through FFMPEG to create an uncompressed grayscale rgb24 avi file, depending on
  where the .mp4 file has been sourced from will produce a different internally structured avi file as output from FFMPEG. Ie, the file header
  and interframe header sizes differ.

  The ffmpeg command i am using is :
  ffmpeg.exe -i source.mp4 -b 1150 -r 20.97 -g 120 -an -vf format=gray -f rawvideo -pixfmt rgb24 -s 384x216 -vcode rawvideo -y fileX.avi

  So far I have identified that .mp4 files generated by my Samsung S5 mobile phone differ from .mp4 files generated by Power Director 14. So I suspect there are different variations of .mp4 files.

  I have written some software which steps into the FFMPEG output .avi file to extract video frames, but it requires fixed offset positions to work so I can only make it work for one variation of .mp4.