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• Joining Lots of clips with crossfade filter using FFmpeg

  26 juillet 2020, par Mr. Who

  I have many video-only clips and I would like to join them with crossfade filter using FFmpeg. My Idea was that I join first two then join it with the next and so on. I implemented the loop in the python and run bash commend using os.system(). My code has been demonstrated below :

  


  out_n = '0.mp4' # output of step n (current step)
for i in range(1,10):
    out_np1 = 'mm%d.mp4'%(i)  # output of step n+1 (next step)
    t0 = time.time() 
    o = os.system('ffmpeg  -i %s -i %d.mp4  -f lavfi -i "color=black:s=1920x1080:d=9" -filter_complex "[0:v]format=pix_fmts=yuva420p,fade=t=out:st=4:d=1:alpha=1,setpts=PTS-STARTPTS[va0];[1:v]format=pix_fmts=yuva420p,fade=t=in:st=0:d=1:alpha=1,setpts=PTS-STARTPTS+4/TB[va1];[2:v][va0]overlay[over1];[over1][va1]overlay=format=yuv420[outv]" -vcodec libx264 -map [outv] %s'%(out_n, i, out_np1))
    print('# %d'%i,(time.time() - t0)/60,o)
    os.remove(out_n) 
    out_n = out_np1  


  


  My Problem is that it won't work properly, the very last output does not even contain all of the last clip and there is no trace of previous ones.

  


• FFMPEG RTMP stream that is recorded by Nginx loses quality

  31 octobre 2022, par Devin Dixon

  I have an Nginx RTMP Replay server with the following config :

  


  user www-data;
worker_processes auto;
pid /run/nginx.pid;
include /etc/nginx/modules-enabled/*.conf;

events {
    worker_connections 768;
    # multi_accept on;
}

http {

    ##
    # Basic Settings
    ##

    sendfile on;
    tcp_nopush on;
    tcp_nodelay on;
    keepalive_timeout 65;
    types_hash_max_size 2048;
    # server_tokens off;

    # server_names_hash_bucket_size 64;
    # server_name_in_redirect off;

    include /etc/nginx/mime.types;
    default_type application/octet-stream;

    ##
    # SSL Settings
    ##

    ssl_protocols TLSv1 TLSv1.1 TLSv1.2 TLSv1.3; # Dropping SSLv3, ref: POODLE
    ssl_prefer_server_ciphers on;

    ##
    # Logging Settings
    ##

    access_log /var/log/nginx/access.log;
    error_log /var/log/nginx/error.log;

    ##
    # Gzip Settings
    ##

    gzip on;

    # gzip_vary on;
    # gzip_proxied any;
    # gzip_comp_level 6;
    # gzip_buffers 16 8k;
    # gzip_http_version 1.1;
    # gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

    ##
    # Virtual Host Configs
    ##

    include /etc/nginx/conf.d/*.conf;
    include /etc/nginx/sites-enabled/*;
}


#mail {
#   # See sample authentication script at:
#   # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
# 
#   # auth_http localhost/auth.php;
#   # pop3_capabilities "TOP" "USER";
#   # imap_capabilities "IMAP4rev1" "UIDPLUS";
# 
#   server {
#       listen     localhost:110;
#       protocol   pop3;
#       proxy      on;
#   }
# 
#   server {
#       listen     localhost:143;
#       protocol   imap;
#       proxy      on;
#   }
#}

rtmp {
    server {
        listen 1935;
        chunk_size 4096;

        application live {
            live on;
            #Set this to "record off" if you don't want to save a copy of your broadcasts
            record all;
            # The directory in which the recordings will be stored.
            record_path /var/www/html/recordings;
            record_unique on;
            record_suffix -%d-%b-%y-%T.flv;
            on_record_done http://127.0.0.1:3000/recorded;

            # Turn on HLS
            exec /usr/bin/ffmpeg -i rtmp://127.0.0.1:1935/live/$name -map 0:v -c:v copy -map 0:a -c:a copy -map 0:a -f flv rtmp://127.0.0.1/show/$name;
        }

        application show {
            live on;
            # Turn on HLS
            hls on;
            hls_path /mnt/hls/;
            hls_fragment 3;
            hls_playlist_length 60;
            # disable consuming the stream from nginx as rtmp
            deny play all;
        }
    }
}


  


  The stream that that is pushed the stream into nginx looks great ! But the nginx recording looks very granny and pixelated. What could be causing the loss in quality as nginx records the stream ?

  


• avcodec/svq1enc : Workaround GCC bug 102513

  25 octobre 2022, par Andreas Rheinhardt

  avcodec/svq1enc : Workaround GCC bug 102513
  GCC 11 has a bug : When it creates clones of recursive functions
  
  (to inline some parameters), it clones a recursive function
  
  eight times by default, even when this exceeds the recursion
  
  depth. This happens with encode_block() in libavcodec/svq1enc.c
  
  where a parameter level is always in the range 0..5 ;
  
  but GCC 11 also creates functions corresponding to level UINT_MAX
  
  and UINT_MAX - 1 (on -O3 ; -O2 is fine).
  Using such levels would produce undefined behaviour and because
  
  of this GCC emits bogus -Warray-bounds warnings for these clones.
  Since commit d08b2900a9f0935959303da668cb00a8a7245228, certain
  
  symbols that are accessed like ff_svq1_inter_multistage_vlc[level]
  
  are declared with hidden visibility, which allows compilers
  
  to bake the offset implied by level into the instructions
  
  if level is a compile-time constant as it is in the clones.
  
  Yet this leads to insane offsets for level == UINT_MAX which
  
  can be incompatible with the supported offset ranges of relocations.
  
  This happens in the small code model (the default code model for
  
  AArch64).
  This commit therefore works around this bug by disabling cloning
  
  recursive functions for GCC 10 and 11. GCC 10 is affected by the
  
  underlying bug (see
  
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102513), so the workaround
  
  also targets it, although it only produces three versions of
  
  encode_block(), so it does not seem to trigger the actual issue here.
  The issue has been mitigated in GCC 12.1 (it no longer creates clones
  
  for impossible values ; see also commit
  
  1cb7fd317c84117bbb13b14851d62f77f57bb9ce), so the workaround
  
  does not target it.
  Reported-by : J. Dekker <jdek@itanimul.li>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  
  Signed-off-by : J. Dekker <jdek@itanimul.li>
  

  • [DH] libavcodec/svq1enc.c