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• avformat/mpegtsenc : fix incorrect PCR selection with multiple programs

  2 août 2019, par Marton Balint

  avformat/mpegtsenc : fix incorrect PCR selection with multiple programs
  The MPEG-TS muxer had a serious bug related to the use of multiple programs :
  
  in that case, the PCR pid selection was incomplete for all services except one.
  
  This patch solves this problem and selects a stream to become PCR for each
  
  service, preferably the video stream.
  This patch also moves pcr calculation attributes to MpegTSWriteStream from
  
  MpegTSService. PCR is a per-stream and not per-service thing, so it was
  
  misleading to refer to it as something that is per-service.
  Also remove *service from MpegTSWriteStream because a stream can belong to
  
  multiple services so it was misleading to select one for each stream.
  You can check the result with this example command :
  ./ffmpeg -loglevel verbose -y -f lavfi -i \
  
    "testsrc=s=64x64:d=10,split=2[out0][tmp1] ;[tmp1]vflip[out1] ;sine=d=10,asetnsamples=1152[out2]" \
  
    -flags +bitexact -fflags +bitexact -sws_flags +accurate_rnd+bitexact  \
  
    -codec:v libx264 -codec:a mp2 -pix_fmt yuv420p \
  
    -map '0:v:0' \
  
    -map '0:v:1' \
  
    -map '0:a:0'  \
  
    -program st=0:st=2 -program st=1:st=2 -program st=2 -program st=0 -f mpegts out.ts
  You should now see this :
  [mpegts @ 0x37505c0] service 1 using PCR in pid=256
  
  [mpegts @ 0x37505c0] service 2 using PCR in pid=257
  
  [mpegts @ 0x37505c0] service 3 using PCR in pid=258
  
  [mpegts @ 0x37505c0] service 4 using PCR in pid=256
  Fixes ticket #8039.
  v2 : a video is stream is preferred if there are no programs, just like before
  
  the patch.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mpegtsenc.c

• installing yasm / nasm on heroku with vulcan

  21 novembre 2013, par scientiffic

  I'm trying to do a build of ffmpeg on Heroku, and I need to use libvpx. In order to install libvpx, I need to have nasm or yasm. I tried installing both using vulcan, but I keep getting the error Neither yasm not nasm has been found

  Here is what I did

  Installing Nasm

  • get nasm source from http://www.linuxfromscratch.org/blfs/view/svn/general/NASM.html
  • tar file using : tar -xJf nasm-2.10.09.tar.xz
  • build using : vulcan build -v -s . -c "./configure -prefix=/app/vendor/nasm && make && make install"
  • add the output of the tar file from vulcan to vendor/nasm
  • push to heroku

  Installing Yasm

  • get yasm source from http://www.linuxfromscratch.org/blfs/view/svn/general/yasm.html
  • extra tar file and build using : vulcan build -v -s . -c "./configure -prefix=/app/vendor/yasm && make && make install"
  • add the output of the tar file from vulcan to vendor/yasm
  • push to heroku

  Installing Libvpx

  • get libvpx source from http://www.linuxfromscratch.org/blfs/view/svn/multimedia/libvpx.html
  • build libvpx using : vulcan build -v -s . -c "./configure —enable-shared —disable-static —prefix=/app/vendor/llibvpx && make && make install"

  Attemping to build libvpx yields this error :

  Packaging local directory... /.rvm/gems/ruby-1.9.2-p320/gems/vulcan-0.8.2/lib/vulcan/cli.rb:49: warning: Insecure world writable dir /usr/local in PATH, mode 040777
  
  done
  
  Uploading source package... done
  
  Building with: ./configure --enable-shared --disable-static --prefix=/app/vendor/llibvpx && make && make install
  
  Configuring selected codecs
  
    enabling vp8_encoder
  
    enabling vp8_decoder
  
  Configuring for target 'x86_64-linux-gcc'
  
    enabling x86_64
  
    enabling pic
  
    enabling runtime_cpu_detect
  
    enabling mmx
  
    enabling sse
  
    enabling sse2
  
    enabling sse3
  
    enabling ssse3
  
    enabling sse4_1
  
  **Neither yasm nor nasm have been found**
  
  
  
  Configuration failed. This could reflect a misconfiguration of your
  
  toolchains, improper options selected, or another problem. If you
  
  don't see any useful error messages above, the next step is to look
  
  at the configure error log file (config.err) to determine what
  
  configure was trying to do when it died.

  How can I successfully build libvpx on heroku using vulcan ?

  The instructions I've been (loosely) following are from here :

  https://gist.github.com/czivko/4392472

  And the reason I need to use libvpx is that I'm using the carrierwave-video gem in my Rails app to convert videos, and it needs libvpx to convert to webm to support video playback in Firefox.

• Restream ongoing Youtube live stream using ffmpeg

  19 juin 2020, par Steve Mitto

  Is there a way I can pull an ongoing live video from youtube(maybe with sth like youtube-dl) and restream it using FFmpeg to another social media platform ?

  



  Will appreciate any helpful response.

  



  Thank you.