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• Streaming video over named PIPE with limited "channel" bandwidth

  13 mars 2019, par fmagno

  I have a video container vid.mp4 that I want to play with ffplay through a named PIPE and be able to tweak the maximum bandwidth allowed by the "channel". Follows what I did :

  1. Create a named PIPE :

  mkfifo pipe_in

  2. Send the container to the pipe with a limited bandwidth (150kB/s) with the help of pipe viewer pv :

  cat vid.mp4 | pv -L 150k > pipe_in

  3. Play the video with ffplay :

  ffplay cache:./pipe_in

  My expectation : To watch the video come through immediately but slowly given the bandwidth constraint.

  What really happens : The video begins to show at normal speed only when command 2. finishes running.

  Thank you in advance !

• ffmpeg issues "501 Not Implemented" while recording an RTSP stream

  28 février 2019, par atsushi

  I have a 4K camera (Sony SNC-VB770) streaming RTSP.

  I’m trying to record the stream into files (each has handy length, say, 1hour)
  using a simple script to repeatedly launch ffmpeg (ver 4.1) :

  while : ; do
  
    # (set $url and $outfile, and then)
  
    ffmpeg -rtsp_transport tcp -t 3600 -y -i $url -c copy -map 0:0 -b:v 16000k $outfile
  
  done

  If I run the script on a local PC directly connected to the camera, it works (longer than a week, at least).
  However, if I do the same on a server machine located in a data center, it fails randomly with no error message.
  Sometimes it runs for a few days, sometimes it dies in one minutes.

  Typical output looks like the following :

  # devname: snc-vb770
  
  # url: rtsp://10.40.35.90/media/video1
  
  # vb: 16000k
  
  # datefmt %d%H
  
  # addtimestamp 0
  
  no timestamp
  
  ffmpeg version 4.1 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 4.4.7 (GCC) 20120313 (Red Hat 4.4.7-18)
  
    configuration: --prefix=/usr/local/ffmpeg-4.1 --enable-openssl --enable-gpl --enable-version3 --enable-nonfree --enable-shared --enable-libx264 --enable-libvorbis --enable-filter=drawtext --enable-libfreetype --enable-libfribidi --enable-fontconfig
  
    libavutil      56. 22.100 / 56. 22.100
  
    libavcodec     58. 35.100 / 58. 35.100
  
    libavformat    58. 20.100 / 58. 20.100
  
    libavdevice    58.  5.100 / 58.  5.100
  
    libavfilter     7. 40.101 /  7. 40.101
  
    libswscale      5.  3.100 /  5.  3.100
  
    libswresample   3.  3.100 /  3.  3.100
  
    libpostproc    55.  3.100 / 55.  3.100
  
  Input #0, rtsp, from 'rtsp://10.40.35.90/media/video1':
  
    Metadata:
  
      title           : Sony RTSP Server
  
    Duration: N/A, start: 0.066667, bitrate: N/A
  
      Stream #0:0: Video: h264 (High), yuv420p(tv, bt709, progressive), 3840x2160 [SAR 1:1 DAR 16:9], 14.99 fps, 14.99 tbr, 90k tbn, 29.97 tbc
  
  Output #0, mp4, to './2811.mp4':
  
    Metadata:
  
      title           : Sony RTSP Server
  
      encoder         : Lavf58.20.100
  
      Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 3840x2160 [SAR 1:1 DAR 16:9], q=2-31, 16000 kb/s, 14.99 fps, 14.99 tbr, 90k tbn, 90k tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp4 @ 0x24e4ec0] Timestamps are unset in a packet for stream 0. This is deprecated and will stop working in the future. Fix your code to set the timestamps properly
  
  [mp4 @ 0x24e4ec0] pts has no value
  
  [mp4 @ 0x24e4ec0] Non-monotonous DTS in output stream 0:0; previous: 0, current: 0; changing to 1. This may result in incorrect timestamps in the output file.
  
  frame=   33 fps=0.0 q=-1.0 size=    1792kB time=00:00:02.00 bitrate=7332.9kbits/s speed=3.57x
  
  ...
  
  frame=  104 fps=8.4 q=-1.0 Lsize=    6532kB time=00:00:06.74 bitrate=7939.6kbits/s speed=0.548x
  
  video:6531kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.023506%

  I’ve looked into RTSP packet and found an "RTSP/1.0 501 Not Implemented" is sent from ffmpeg to the camera.
  After that the camera eventually sent back "RTSP/1.0 505 RTSP Version not supported" and then ffmpeg quits shortly.

  The "501" packet seems to be generated by libavformat/rtsp.c:ff_rtsp_read_reply(),
  when ffmpeg receive a malformed RTSP packet with method=(null), status_code=0.
  I don’t know why such packets arrive at random timing and who is wrong (maybe the camera, maybe any of network switches or routers in the middle of the network path from the camera to the server machine).
  But anyway, I don’t want the recording to be stopped
  due to those malformed packets.

  Is there any workaround to make ffmpeg ignore invalid RTSP packets and just continue the recording ?

  Additional information :

  • I’ve tested the recording with both ffmpeg ver4.1 and 2.8.4 and no difference observed.

  • No difference observed at lower resolution nor at lower bitrate.

  • I have 3 cameras from various manufacturers in the same network environment.
    All of the three are working without problem for more than a month.
    Only the Sony SNC-VB770 shows the strange behavior.

• Pausing ffmpeg : "slow motion" after resume

  15 février 2019, par macmac

  I’m trying to pause/resume ffmpeg process during encoding. The OS is Windows.

  I pause ffmpeg.exe and resume it after a while. The problem is, that during replaying of created movie, it looks like played in "slow-motion" for some time since the moment of pausing. After a while replay speed catches up with actual frame rate.

  The "slow-motion time" seems similar to pause-time, but it is rather not 1:1 relation.

  I use Win32 process/thead API to pause and resume ffmpeg process. But it behaves exactly same when paused/resumed using Windows resource monitor, or using keyboard Pause key.

  Interestingly, same problem occurs when you enter ’c’ key at ffmpeg input and wait a while instead of entering command. Looks like the process blocks at I/O function and then has a problem with frame timestamps.

  I’m neither ffmpeg nor multimedia expert, but it looks to me like problem with some kind of time-stamps and the gap between the moment ffmpeg is paused and resumed.

  Is there maybe some ffmpeg commands or filters that could fix it ? Or a better way to pause/resume it during recording ?