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• ffmpeg with double ethernet interfaces works wrong

  21 janvier 2019, par CharlesCui

  A server with double interfaces.

  1. One(eht0) is used for WAN which provides http/ssh services for internet users.

  2. The other(eth1) is used to receive multicast data from intranet.

  218.108.132.177 is public network gateway.

  125.210.198.1 is private network gateway.

  233.49.3.*/24 is multicast address.

  10.0.11.*/24 is the source of multicast data.

  When the route table is like below, ffmpeg can’t read the udp data from eth1, ffmpeg hung up :

  rrca@rcasnap02:~$ route
  
  Kernel IP routing table
  
  Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
  
  218.108.132.176 *               255.255.255.252 U     0      0        0 eth0
  
  125.210.198.0   *               255.255.255.240 U     0      0        0 eth1
  
  default         218.108.132.177 0.0.0.0         UG    100    0        0 eth0
  
  default         125.210.198.1   0.0.0.0         UG    100    0        0 eth1

  or

  rrca@rcasnap02:~$ route
  
  Kernel IP routing table
  
  Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
  
  218.108.132.176 *               255.255.255.252 U     0      0        0 eth0
  
  125.210.198.0   *               255.255.255.240 U     0      0        0 eth1
  
  default         218.108.132.177 0.0.0.0         UG    100    0        0 eth0
  
  10.0.11.0       125.210.198.1   0.0.0.0         UG    100    0        0 eth1

  or

  rrca@rcasnap02:~$ route
  
  Kernel IP routing table
  
  Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
  
  218.108.132.176 *               255.255.255.252 U     0      0        0 eth0
  
  125.210.198.0   *               255.255.255.240 U     0      0        0 eth1
  
  default         218.108.132.177 0.0.0.0         UG    100    0        0 eth0
  
  233.49.3.0      125.210.198.1   255.255.255.0   UG    100    0        0 eth1

  I want to the ffmpeg work right,but now I think the two default route in route table disturb eachother, and I take a try, when the public gateway route is deleted, or the private gateway route is at the head of public default gateway route, ffmpeg works well, I think it read multicast from eth1.But the route table is not thus, ffmpeg can’t read data from eth1, I think it read data on eth0(which is not private network interface).

  How to do ffmpeg works well with two interfaces at the same time ?

• ffmpeg : cut video but getting the wrong length

  2 août 2024, par nathan wu

  I'm using ffmpeg to cut a video.
Here is the input information :

  



      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 5113 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)


  



  And this is the command I use :

  



      ffmpeg -y -ss 10 -t 5 -i test.mp4 -c copy output.mp4


  



  But the output duration is about 9.66 seconds.

  



  It worked when I removed the '-c copy' option or the input doesn't contain the 'tv, bt709' tag. But it's slower.

  



  I wonder how I can use '-c copy' and get the right piece of video I need ?

  


• ffmpeg low speed and wrong bitrate

  31 août 2018, par ngc3o34

  My goal is to compress video making it’s bitrate lower.
  For experiment I used following command

  ffmpeg -ss 00:00:00 -i V.mkv -to 00:10:00 -c:a copy -b:v 7500k -maxrate 7500k -minrate 5500k -bufsize 1M V7500.mkv

  1. What are possible reasons speed of conversion was close to 1.0x utilizing all 8 cores ?
  2. Bitrate of output video stream is about 4700 (5500 was set as minrate). Is there proper way to specify bitrate ?

  Stream mapping:
  
    Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  [libx264 @ 0x55e54ad189a0] using SAR=1/1
  
  [libx264 @ 0x55e54ad189a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
  
  [libx264 @ 0x55e54ad189a0] profile High, level 4.0
  
  [libx264 @ 0x55e54ad189a0] 264 - core 152 r2854 e9a5903 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=23 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=cbr mbtree=1 bitrate=7500 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=7500 vbv_bufsize=1000 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00
  
  Output #0, matroska, to 'V7500.mkv':
  
    Metadata:
  
      title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
  
      encoder         : Lavf57.83.100
  
      Chapter #0:0: start 0.000000, end 600.000000
  
      Metadata:
  
        title           : Chapter 01
  
      Stream #0:0(eng): Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 1920x804 [SAR 1:1 DAR 160:67], q=-1--1, 7500 kb/s, 23.98 fps, 1k tbn, 23.98 tbc (default)
  
      Metadata:
  
        title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
  
        DURATION        : 02:17:03.277000000
  
        encoder         : Lavc57.107.100 libx264
  
      Side data:
  
        cpb: bitrate max/min/avg: 7500000/0/7500000 buffer size: 1000000 vbv_delay: -1
  
      Stream #0:1(eng): Audio: aac (LC) ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, fltp (default)
  
      Metadata:
  
        title           : Valerian.and.the.City.of.a.Thousand.Planets.2017.1080p.BluRay.x264.DTS-HD.MA.7.1-FGT
  
        ENCODER         : Lavc57.107.100 aac
  
        DURATION        : 02:17:03.317000000
  
  Past duration 0.994987 too large
  
  frame=14385 fps= 31 q=-1.0 Lsize=  363641kB time=00:09:59.99 bitrate=4964.9kbits/s speed=1.28x