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• How can I store a live stream when internet connection is interrupted ?

  5 juin 2019, par Marcello Moreira

  I’m building a solution using drone and 3g/4g connection.
  I have an IP camera encoded in H.264 by a hardware encoder connected to a raspberry pi and a 3g/4g moldem. The hardware encoder livestream de video via RTMP to a remote server I have. All these devices are in a moving platform, and sometimes the moldem loses connection with internet for a few seconds/minutes. When this happens, I want to store the live footage in the raspberry with ffmpeg, and when the connection restores I can send it back to the server. I have access to the encoded livestream from the raspberry pi over LAN even when internet is down.

  I do not know how and where should I start.
  I see two approaches for this.

  First approach

  One is to do all the streaming via ffmpeg, and disable the automatic hardware stream, when ffmpeg detects that it can’t send stream to the remote server, it starts to store the video (like a buffer) until the connection is restore. The issue with this, is that I don’t know if ffmpeg can detect if internet connection is down, and how can I buffer the video. Also by doing this, when connection is restored, live video would have a huge delay, and I can’t have lot’s of delay in my solution.

  Second approach

  The second is simultaneously store with ffmpeg the live video, when internet goes down, a process records the timestamp, and keeps watching until internet connection is restored. Then it sends to my server only the missing piece. At my server I would need to figure out a way to join those streams back up.. (I would gladly accept tips on that too). Issue with this is that there’s limited space in my raspberry, so I can only store a limited amount. Also, my device may be turned off when it lands so I need to send the video recording ASAP after connection is restored.

  So, which approach seems to be the better one ?

• Store a live stream when internet connection is interrupted ?

  6 juin 2019, par Marcello Moreira

  I’m building a solution using drone and 3g/4g connection.
  I have an IP camera encoded in H.264 by a hardware encoder connected to a raspberry pi and a 3g/4g modem. The hardware encoder livestream de video via RTMP to a remote server I have. All these devices are in a moving platform, and sometimes the modem loses connection with internet for a few seconds/minutes. When this happens, I want to store the live footage in the raspberry with ffmpeg, and when the connection restores I can send it back to the server. I have access to the encoded livestream from the raspberry pi over LAN even when internet is down.

  I do not know how and where should I start.
  I see two approaches for this.

  First approach

  One is to do all the streaming via ffmpeg, and disable the automatic hardware stream, when ffmpeg detects that it can’t send stream to the remote server, it starts to store the video (like a buffer) until the connection is restore. The issue with this, is that I don’t know if ffmpeg can detect if internet connection is down, and how can I buffer the video. Also by doing this, when connection is restored, live video would have a huge delay, and I can’t have lot’s of delay in my solution.

  Second approach

  The second is simultaneously store with ffmpeg the live video, when internet goes down, a process records the timestamp, and keeps watching until internet connection is restored. Then it sends to my server only the missing piece. At my server I would need to figure out a way to join those streams back up.. (I would gladly accept tips on that too). Issue with this is that there’s limited space in my raspberry, so I can only store a limited amount. Also, my device may be turned off when it lands so I need to send the video recording ASAP after connection is restored.

  So, which approach seems to be the better one ?

• Using ffmpeg on Ubuntu, how can the audio and video from an audio-video USB capture device be recorded ?

  11 avril 2022, par BlandCorporation

  I have a USB audio-video capture device, something used to digitize video cassettes. I want to record both the video and audio from the device to a video file that has dimensions 720x576 and video codec H.264 and good audio quality.

  


  I am able to record video from the device using ffmpeg and I am able to see video from the device using MPlayer. I am able also to see that audio is being delivered from the device to the computer by looking at Input tab of the Sound Preferences window or by recording the audio using Audacity, however the audio gets delivered from the device apparently only when the video is being accessed using ffmpeg or MPlayer.

  


  I have tried to get ffmpeg to record the audio and I have tried to get MPlayer to play the audio and my efforts have not been successful.

  


  The device is "Pinnacle Dazzle DVC 90/100/101" (as returned by v4l2-ctl --list-devices). The sound cards listing shows it as "DVC100" :

  


  $ cat /proc/asound/cards 
 0 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0x601d118000 irq 171
 1 [DVC100         ]: USB-Audio - DVC100
                      Pinnacle Systems GmbH DVC100 at usb-0000:00:14.0-4, high speed
29 [ThinkPadEC     ]: ThinkPad EC - ThinkPad Console Audio Control
                      ThinkPad Console Audio Control at EC reg 0x30, fw N2LHT33W


  


  The PulseAudio listing for the device is as follows :

  


  $ pactl list cards short
0   alsa_card.pci-0000_00_1f.3  module-alsa-card.c
14  alsa_card.usb-Pinnacle_Systems_GmbH_DVC100-01   module-alsa-card.c


  


  The following ffmpeg command successfully records video, but records severely distorted, broken and out-of-sync audio :

  


  ffmpeg -y -f rawvideo -f alsa -thread_queue_size 2048 -ar 48000 -i hw:0 \
    -c:a aac -video_size 720x576 -pixel_format uyvy422 -i /dev/video2 out.mp4


  


  The following MPlayer command successfully displays the video but does not play the audio :

  


  mplayer -tv driver=v4l2:norm=PAL:device=/dev/video2:width=720:height=576 \
    -ao alsa:device=hw=1.0 -vf pp=lb tv://


  


  Now, when the above MPlayer command is running (not the ffmpeg command) and displaying the input video in a window, Audacity can be opened and set recording audio, and it records the audio from the device clearly and in good quality. While Audacity is doing this, the input device is listed in pavucontrol as "Dazzle DVC Audio Device Analogue Stereo". Equivalently, arecord can be used also to record the audio using the following command (with output shown) :

  


  $ arecord -vv -D plughw:DVC100 -fdat out.wav
Recording WAVE 'out.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Stereo
Plug PCM: Hardware PCM card 1 'DVC100' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 16
  buffer_size  : 24000
  period_size  : 6000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 6000
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 24000
  silence_threshold: 0
  silence_size : 0
  boundary     : 6755399441055744000
  appl_ptr     : 0
  hw_ptr       : 0


  


  Looking at the output of arecord -L, I tried a variety of audio device input names with ffmpeg and none of them seemed to work. So, for example, I tried commands like the following :

  


  ffmpeg -y -f rawvideo -f alsa -i plughw:DVC100 \
    -video_size 720x576 -pixel_format uyvy422 -i /dev/video2 out.mp4


  


  And tried the following audio device names :

  


  plughw:DVC100
plughw:CARD=DVC100,DEV=0
hw:CARD=DVC100,DEV=0
plughw:CARD=DVC100
sysdefault:CARD=DVC100
iec958:CARD=DVC100,DEV=0
dsnoop:CARD=DVC100,DEV=0


  


  So, how might I get ffmpeg to record the audio successfully to the video file ? Is there some alternative approach to this problem ?

  


  ---

  


  EDIT : The relevant output from the command pactl list sources is as follows :

  


  Source #20
    State: SUSPENDED
    Name: alsa_input.usb-Pinnacle_Systems_GmbH_DVC100-01.analog-stereo
    Description: Dazzle DVC100 Audio Device Analogue Stereo
    Driver: module-alsa-card.c
    Sample Specification: s16le 2ch 48000Hz
    Channel Map: front-left,front-right
    Owner Module: 45
    Mute: no
    Volume: front-left: 99957 / 153% / 11.00 dB,   front-right: 99957 / 153% / 11.00 dB
            balance 0.00
    Base Volume: 35466 /  54% / -16.00 dB
    Monitor of Sink: n/a
    Latency: 0 usec, configured 0 usec
    Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY 
    Properties:
        alsa.resolution_bits = "16"
        device.api = "alsa"
        device.class = "sound"
        alsa.class = "generic"
        alsa.subclass = "generic-mix"
        alsa.name = "USB Audio"
        alsa.id = "USB Audio"
        alsa.subdevice = "0"
        alsa.subdevice_name = "subdevice #0"
        alsa.device = "0"
        alsa.card = "1"
        alsa.card_name = "DVC100"
        alsa.long_card_name = "Pinnacle Systems GmbH DVC100 at usb-0000:00:14.0-4, high speed"
        alsa.driver_name = "snd_usb_audio"
        device.bus_path = "pci-0000:00:14.0-usb-0:4:1.1"
        sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-4/1-4:1.1/sound/card1"
        udev.id = "usb-Pinnacle_Systems_GmbH_DVC100-01"
        device.bus = "usb"
        device.vendor.id = "2304"
        device.vendor.name = "Pinnacle Systems, Inc."
        device.product.id = "021a"
        device.product.name = "Dazzle DVC100 Audio Device"
        device.serial = "Pinnacle_Systems_GmbH_DVC100"
        device.string = "front:1"
        device.buffering.buffer_size = "352800"
        device.buffering.fragment_size = "176400"
        device.access_mode = "mmap+timer"
        device.profile.name = "analog-stereo"
        device.profile.description = "Analogue Stereo"
        device.description = "Dazzle DVC100 Audio Device Analogue Stereo"
        alsa.mixer_name = "USB Mixer"
        alsa.components = "USB2304:021a"
        module-udev-detect.discovered = "1"
        device.icon_name = "audio-card-usb"
    Ports:
        analog-input-linein: Line In (priority: 8100)
    Active Port: analog-input-linein
    Formats:
        pcm


  


  I tested the name from this with ffmpeg (version 4.3.1, compiled with -enable-libpulse) in the following way :

  


  ffmpeg -y -f video4linux2 -f pulse \
    -i alsa_input.usb-Pinnacle_Systems_GmbH_DVC100-01.analog-stereo \
    -video_size 720x576 -pixel_format uyvy422 -i /dev/video2 out.mp4


  


  Unfortunately this hasn't worked.