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• How do you use FFMPEG to transcode h264_qsv from Apple PRORES Quicktime ?

  4 décembre 2022, par RCJetPilot

  I am trying to transcode an Apple Prores 444 to H.264 using qsv without success.

  


  If I use this command line :

  


  ffmpeg -i 10minute_Pipeline_Test.mov -c:v h264_qsv -c:a aac -pix_fmt qsv  chris.mp4

  


  I get :

  


  ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
  configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-nonfree --enable-libmfx
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '10minute_Pipeline_Test.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537134592
    compatible_brands: qt  
    creation_time   : 2020-12-19T12:43:38.000000Z
    com.apple.quicktime.author: 
    com.apple.quicktime.comment: 
    com.apple.quicktime.copyright: 
    com.apple.quicktime.description: 
    com.apple.quicktime.director: 
    com.apple.quicktime.genre: 
    com.apple.quicktime.information: 
    com.apple.quicktime.keywords: 
    com.apple.quicktime.producer: 
    com.apple.quicktime.displayname: 
    timecode        : 12:43:37;28
  Duration: 00:10:06.72, start: 0.000000, bitrate: 167429 kb/s
    Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 1970-01-04T00:49:14.000000Z
      timecode        : 12:43:37;28
    Stream #0:1(eng): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, GBR, progressive), 1280x720, 164985 kb/s, SAR 1:1 DAR 16:9, 59.94 fps, 59.94 tbr, 60k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:04.000000Z
    Stream #0:2(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Stream #0:3(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Metadata:
      creation_time   : 2003-10-05T11:26:56.000000Z
File 'chris.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:1 -> #0:0 (prores (native) -> h264 (h264_qsv))
  Stream #0:2 -> #0:1 (pcm_s24le (native) -> aac (native))
Press [q] to stop, [?] for help
[h264_qsv @ 0x56265b81a800] Selected ratecontrol mode is unsupported
[h264_qsv @ 0x56265b81a800] Low power mode is unsupported
[h264_qsv @ 0x56265b81a800] Current frame rate is unsupported
[h264_qsv @ 0x56265b81a800] Current picture structure is unsupported
[h264_qsv @ 0x56265b81a800] Current resolution is unsupported
[h264_qsv @ 0x56265b81a800] Current pixel format is unsupported
[h264_qsv @ 0x56265b81a800] some encoding parameters are not supported by the QSV runtime. Please double check the input parameters.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!
user@NUC:~$ ffmpeg -i 10minute_Pipeline_Test.mov -c:v h264_qsv -c:a aac -pix_fmt qsv  chris.mp4
ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
  configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-nonfree --enable-libmfx
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '10minute_Pipeline_Test.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537134592
    compatible_brands: qt  
    creation_time   : 2020-12-19T12:43:38.000000Z
    com.apple.quicktime.author: 
    com.apple.quicktime.comment: 
    com.apple.quicktime.copyright: 
    com.apple.quicktime.description: 
    com.apple.quicktime.director: 
    com.apple.quicktime.genre: 
    com.apple.quicktime.information: 
    com.apple.quicktime.keywords: 
    com.apple.quicktime.producer: 
    com.apple.quicktime.displayname: 
    timecode        : 12:43:37;28
  Duration: 00:10:06.72, start: 0.000000, bitrate: 167429 kb/s
    Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 1970-01-04T00:49:14.000000Z
      timecode        : 12:43:37;28
    Stream #0:1(eng): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, GBR, progressive), 1280x720, 164985 kb/s, SAR 1:1 DAR 16:9, 59.94 fps, 59.94 tbr, 60k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:04.000000Z
    Stream #0:2(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Stream #0:3(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Metadata:
      creation_time   : 2003-10-05T11:26:56.000000Z
File 'chris.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:1 -> #0:0 (prores (native) -> h264 (h264_qsv))
  Stream #0:2 -> #0:1 (pcm_s24le (native) -> aac (native))
Press [q] to stop, [?] for help
Impossible to convert between the formats supported by the filter 'Parsed_null_0' and the filter 'auto_scaler_0'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #0:1
Conversion failed!


  


  If I use :

  


  ffmpeg -i 10minute_Pipeline_Test.mov -c:v h264_qsv -c:a aac  chris.mp4

  


  I get :

  


  ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
  configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-nonfree --enable-libmfx
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '10minute_Pipeline_Test.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537134592
    compatible_brands: qt  
    creation_time   : 2020-12-19T12:43:38.000000Z
    com.apple.quicktime.author: 
    com.apple.quicktime.comment: 
    com.apple.quicktime.copyright: 
    com.apple.quicktime.description: 
    com.apple.quicktime.director: 
    com.apple.quicktime.genre: 
    com.apple.quicktime.information: 
    com.apple.quicktime.keywords: 
    com.apple.quicktime.producer: 
    com.apple.quicktime.displayname: 
    timecode        : 12:43:37;28
  Duration: 00:10:06.72, start: 0.000000, bitrate: 167429 kb/s
    Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 1970-01-04T00:49:14.000000Z
      timecode        : 12:43:37;28
    Stream #0:1(eng): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, GBR, progressive), 1280x720, 164985 kb/s, SAR 1:1 DAR 16:9, 59.94 fps, 59.94 tbr, 60k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:04.000000Z
    Stream #0:2(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Stream #0:3(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Metadata:
      creation_time   : 2003-10-05T11:26:56.000000Z
File 'chris.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:1 -> #0:0 (prores (native) -> h264 (h264_qsv))
  Stream #0:2 -> #0:1 (pcm_s24le (native) -> aac (native))
Press [q] to stop, [?] for help
Impossible to convert between the formats supported by the filter 'Parsed_null_0' and the filter 'auto_scaler_0'
Error reinitializing filters!
Failed to inject frame into filter network: Function not implemented
Error while processing the decoded data for stream #0:1
Conversion failed!
user@NUC:~$ ffmpeg -i 10minute_Pipeline_Test.mov -c:v h264_qsv -c:a aac  chris.mp4
ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
  configuration: --prefix=/root/ffmpeg_build --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --extra-libs=-ldl --enable-gpl --enable-libass --enable-libfdk-aac --enable-libmp3lame --enable-nonfree --enable-libmfx
  libavutil      56. 31.100 / 56. 31.100
  libavcodec     58. 54.100 / 58. 54.100
  libavformat    58. 29.100 / 58. 29.100
  libavdevice    58.  8.100 / 58.  8.100
  libavfilter     7. 57.100 /  7. 57.100
  libswscale      5.  5.100 /  5.  5.100
  libswresample   3.  5.100 /  3.  5.100
  libpostproc    55.  5.100 / 55.  5.100
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '10minute_Pipeline_Test.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 537134592
    compatible_brands: qt  
    creation_time   : 2020-12-19T12:43:38.000000Z
    com.apple.quicktime.author: 
    com.apple.quicktime.comment: 
    com.apple.quicktime.copyright: 
    com.apple.quicktime.description: 
    com.apple.quicktime.director: 
    com.apple.quicktime.genre: 
    com.apple.quicktime.information: 
    com.apple.quicktime.keywords: 
    com.apple.quicktime.producer: 
    com.apple.quicktime.displayname: 
    timecode        : 12:43:37;28
  Duration: 00:10:06.72, start: 0.000000, bitrate: 167429 kb/s
    Stream #0:0(eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 1970-01-04T00:49:14.000000Z
      timecode        : 12:43:37;28
    Stream #0:1(eng): Video: prores (Standard) (apcn / 0x6E637061), yuv422p10le(tv, GBR, progressive), 1280x720, 164985 kb/s, SAR 1:1 DAR 16:9, 59.94 fps, 59.94 tbr, 60k tbn, 60k tbc (default)
    Metadata:
      creation_time   : 1970-01-01T00:00:04.000000Z
    Stream #0:2(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Stream #0:3(eng): Audio: pcm_s24le (in24 / 0x34326E69), 48000 Hz, mono, s32 (24 bit), 1152 kb/s (default)
    Metadata:
      creation_time   : 2003-10-05T11:26:56.000000Z
File 'chris.mp4' already exists. Overwrite ? [y/N] y
Stream mapping:
  Stream #0:1 -> #0:0 (prores (native) -> h264 (h264_qsv))
  Stream #0:2 -> #0:1 (pcm_s24le (native) -> aac (native))
Press [q] to stop, [?] for help
[h264_qsv @ 0x55b3bb6e8800] Selected ratecontrol mode is unsupported
[h264_qsv @ 0x55b3bb6e8800] Low power mode is unsupported
[h264_qsv @ 0x55b3bb6e8800] Current frame rate is unsupported
[h264_qsv @ 0x55b3bb6e8800] Current picture structure is unsupported
[h264_qsv @ 0x55b3bb6e8800] Current resolution is unsupported
[h264_qsv @ 0x55b3bb6e8800] Current pixel format is unsupported
[h264_qsv @ 0x55b3bb6e8800] some encoding parameters are not supported by the QSV runtime. Please double check the input parameters.
Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height
Conversion failed!


  


  I cannot get ANYTHING to work. I can transcode other h264 files without issue. I cannot seem to transcode this prores file.

  


  Here is a link to the source file if anyone can help I would REALLY appreciate it...

  


  https://www.dropbox.com/s/ejrfzad20yzaifm/10minute_Pipeline_Test.mov?dl=1

  


• 12 ways Matomo Analytics helps you to protect your visitor’s privacy

  5 mai 2020, par InnoCraft — Analytics Tips, Privacy, Security

  This post was originally published on January 11, 2017, and updated on May, 2020.

  At Matomo we think privacy matters. From the beginning, Matomo has had a strong focus on privacy and ensuring the privacy of your visitors and analytics data. 

  Here are some ways how you can ensure your users and visitors privacy by using Matomo (Piwik).

  1. Owning the data gives you power to protect user privacy

  Whether you host Matomo on-premises yourself, or whether you use Matomo’s cloud, YOU keep control of your data and nobody else. By knowing exactly where your data is stored and having full control over what happens to it, you have the power to protect your user’s privacy. No-one else can claim ownership. 

  2. GDPR compliance

  GDPR is one of the most important privacy laws to have come out in the last few years. As such, Matomo takes GDPR compliance very seriously. There’s even a 12-step checklist for you to follow to ensure your Matomo is GDPR compliant. Not only that Matomo is HIPAA, CCPA, LGPD, and PECR compliant.

  3. Data anonymization

  For better privacy by default, Matomo implements a range of data anonymization techniques. One of the main techniques is not recording the full IP address of your visitors. Some countries even require you to anonymize additional info considered Personally Identifiable Information (PII).

  To change the IP anonymization settings go to “Administration > Privacy”. 

  

  4. Configuring Matomo to not process personal data or personally identifiable information (PII)

  To further protect the privacy of your visitors, you can learn how to not process any personal information or PII. 

  5. Deleting old visitor logs

  The is important because visitor logs contain information all the collected raw data about every visitor and every action. You can configure Matomo to automatically delete logs from the database. When you delete old logs, only the real time and visitor log reports will no longer work for this old time period, all other aggregated reports will still work.

  For privacy reasons, we highly recommend that you keep the detailed Matomo logs for only 3 to 6 months and delete older log data. This has one other nice side effect : it will free significant database space, which will, in turn, slightly increase performance !

  

  6. Supporting the Do Not Track preference

  Do Not Track enables users to opt out of any tracking by websites they do not visit, including analytics services, advertising networks, and social platforms. By default, Matomo respects users preference and will not track visitors which have specified “I do not want to be tracked” in their web browsers. Get more information about DoNotTrack.

  To make sure Do Not Track is respected, go to “Administration => Privacy”.

  7. Including an Opt-Out Feature on your website or app

  By embedding the Opt-Out feature in your website, you give your visitors the possibility to opt-out of the tracking. When you go to “Administration > Privacy”, you will be able to copy and paste an HTML Iframe code to embed the opt-out feature for example into your privacy policy page or in your ‘Legal’ page. Your users can then click on a link to opt-out.

  On the Matomo Marketplace there are also some plugins available to customize the Opt-Out experience. For example AjaxOptOut and CustomOptOut.

  

  8. Disabling Live features

  The Real-Time, Visitor Log and Visitor Profile features give you insights into the tracked raw data by showing you details about every visitor and every action they performed. To protect the privacy of your visitors you may decide to prevent access to such features by disabling the “Live” plugin in “Administration => Plugins”. This way only aggregated reports will be shown in your Matomo.

  9. Disabling fingerprinting across websites

  By default, when one of your visitors visits several of your websites, Matomo will create a fingerprint for this user that will be different across the websites to increase the visitors’ privacy. You can make sure that this feature is disabled by going to “Administration => Config file” and verifying that the value of “enable_fingerprinting_across_websites” is set to zero.

  10. Disabling tracking cookies

  Matomo uses first-party cookies to store some information about visitors between visits. In some countries, the legislation requires websites to provide a way for users to opt-out of all tracking, in particular tracking cookies. You can disable cookies by adding one line in the Matomo Javascript code.

  11. Creating the tool of your dreams by developing your own plugins and getting access to the API

  Matomo is an open platform that lets you extend and customise the tracking ; reporting ; and user interface to your needs and to protect your visitors’ privacy the way you want or need it. Learn more in the Matomo Developer Zone. You may also have a look at our Matomo Marketplace where you can find several free and premium features to extend your Matomo.

  12. Transparency

  By default, all information and all collected data in your Matomo server are protected and nobody can access it. However, Matomo allows you to optionally make your collected data public and you can export any Matomo report including the whole dashboard to embed it into your website. This way you can show your users exactly which information you track. When you decide to make reports public, we do our best to protect privacy and automatically hide any Personally Identifiable Information such as the Visitor Profile and we make sure to not show any Visitor IP address and the Visitor ID.

  Bonus tip – A privacy policy template for you

  When you use Matomo to track your visitors, we recommend you update your Privacy Policy to explain how Matomo is used and what data it gathers. Here’s a Privacy Policy template for you to copy on your site.

  Continuous privacy improvements

  We are always interested in improving the privacy. If you miss any feature or have an idea on how to improve the privacy, please let us know.

  More information about all the Matomo features

  If you want to learn more about all the features in Matomo, have a look at our User Guides and FAQ entries.

• Recording usb cam on raspberry pi with ffmpeg - usb troubleshooting

  18 septembre 2017, par Hwy2Hell

  I want to save video from an external usb cam on the raspberry pi 3. In order to avoid voltage drop issues, I use the offical raspberry power supply (2.5 Amp) and connected all usb devices by a separetely powered usb hub :

  pi@raspi:~/appdev/ffmpeg $ lsusb
  
  Bus 001 Device 037: ID 046d:09a1 Logitech, Inc. QuickCam Communicate MP/S5500
  
  Bus 001 Device 036: ID 046d:c03f Logitech, Inc. M-BT85 [UltraX Optical Mouse]
  
  Bus 001 Device 035: ID 04d9:1503 Holtek Semiconductor, Inc. Shortboard Lefty
  
  Bus 001 Device 012: ID 1a40:0101 Terminus Technology Inc. 4-Port HUB
  
  Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
  
  Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. 
  
  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

  When I try to test the functionality by running the following bash script (snippet) :

  function capture
  
  {
  
      capfile=$(date +%F_%Hh%Mm%Ss)
  
      echo saving to $wdir/$capfile.mp4
  
      echo $PATH
  
      ffmpeg -video_size 320x240 -i /dev/video0 \
  
      -vf drawtext="fontsize=18:x=10:y=220:fontcolor=red:\
  
      fontfile=/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf:\
  
      text=%{localtime}" -t 10 $wdir/$capfile.mp4
  
      # change -t to 3600 = 1h
  
  }
  
  
  
  for i in $(seq 1 10)
  
  do
  
      echo
  
      echo Pass $i ...
  
      capture
  
  done

  After a few loop-runs I always see device errors :

  Pass 5 ...
  
  saving to /home/pi/appdev/ffmpeg/2017-09-16_13h31m00s.mp4
  
  /usr/local/bin:/usr/bin/ffmpeg:/usr/bin:/bin:/sbin
  
  ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 4.9.2 (Raspbian 4.9.2-10)
  
    configuration: --arch=armhf --target-os=linux --enable-gpl --enable-libfreetype --enable-mmal --enable-nonfree --enable-omx --enable-omx-rpi
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  /dev/video0: Input/output error

  The kernel message log shows that the usb cam has been resetted :

  pi@raspi:~/appdev/ffmpeg $ dmesg | grep usb
  
  [ 4497.358195] usb 1-1.2.4: new high-speed USB device number 37 using dwc_otg
  
  [ 4497.573440] usb 1-1.2.4: New USB device found, idVendor=046d, idProduct=09a1
  
  [ 4497.573466] usb 1-1.2.4: New USB device strings: Mfr=0, Product=0, SerialNumber=2
  
  [ 4497.573481] usb 1-1.2.4: SerialNumber: A032D310
  
  [ 4497.605698] input: UVC Camera (046d:09a1) as /devices/platform/soc/3f980000.usb/usb1/1-1/1-1.2/1-1.2.4/1-1.2.4:1.0/input/input15
  
  [ 4497.625582] usb 1-1.2.4: Warning! Unlikely big volume range (=3072), cval->res is probably wrong.
  
  [ 4497.625606] usb 1-1.2.4: [5] FU [Mic Capture Volume] ch = 1, val = 4608/7680/1
  
  [ 5268.123764] usb 1-1.2.4: reset high-speed USB device number 37 using dwc_otg

  Next time I start the script, the usb cam gets disconnected and /dev/viedo0 disappears :

  pi@raspi:~/appdev/ffmpeg $ dmesg | grep usb
  
  [ 5621.216896] usb 1-1.2.4: USB disconnect, device number 37
  
  [ 5621.586804] usb 1-1.2.4: new full-speed USB device number 38 using dwc_otg
  
  [ 5621.686694] usb 1-1.2.4: device descriptor read/64, error -32
  
  [ 5621.896583] usb 1-1.2.4: device descriptor read/64, error -32
  
  [ 5622.106572] usb 1-1.2.4: new full-speed USB device number 39 using dwc_otg
  
  [ 5622.206574] usb 1-1.2.4: device descriptor read/64, error -32
  
  [ 5622.416577] usb 1-1.2.4: device descriptor read/64, error -32
  
  [ 5622.626586] usb 1-1.2.4: new full-speed USB device number 40 using dwc_otg
  
  [ 5623.046583] usb 1-1.2.4: device not accepting address 40, error -32
  
  [ 5623.146583] usb 1-1.2.4: new full-speed USB device number 41 using dwc_otg
  
  [ 5623.566603] usb 1-1.2.4: device not accepting address 41, error -32
  
  [ 5623.566670] usb 1-1.2-port4: unable to enumerate USB device

  Has anybody experienced similar problems and can provide a fix for it ?

  What tools can I use to troubleshoot the usb communication on the pi ?