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• ffmpeg recording audio / video sync issues [closed]

  1er novembre 2022, par sling jones

  I'm using ffmpeg to record NTSC analog video on Linux Fedora 36 using a Blackmagic Intensity Pro 4K for video and a Scarlett 2i2 for audio. I'm using a TBC to avoid dropped frames and to ensure a constant S-Video Y/C framerate on the analog end.

  


  The problem I'm running into is that on playback the audio will start out relatively in sync with the video at the beginning of the captured file but will eventually run ahead of the video eventually becoming many seconds off.

  


  Nothing I do seems to change this or change the degree to which it happens. The audio and video stay in sync throughout the entire video as I'm monitoring the source so I don't understand how they can diverge so much once encoded into a digital file ?

  


  Here is the command I am using :

  


  ffmpeg -hwaccel cuda -fflags +igndts -format_code ntsc -f decklink -raw_format auto -vsync passthrough -rtbufsize 1500M -thread_queue_size 512 -i 'Intensity Pro 4K' -f pulse -rtbufsize 500M -thread_queue_size 512 -i 'Scarlett 2i2 Camera Analog Stereo' -c copy -map 0:1 -map 1:0 "/tmp/ffmpeg-raw/file-raw.avi"


  


  here's the ffprobe output from one of my files :

  


  Input #0, avi, from 'test2-raw.avi':
  Metadata:
    software        : Lavf59.33.100
  Duration: 00:11:42.87, start: 0.000000, bitrate: 169341 kb/s
  Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x486, 167801 kb/s, 59.94 fps, 59.94 tbr, 59.94 tbn
  Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s



  


  As you can see in my code snippet, I've been throwing things at the wall for a bit. I've tried different rtbufsizes, adding -copyts, and going through the different -vsync options. I've tried it with and without hardware acceleration ( I do have a NVIDIA card), +igdts did get rid of a warning but did not help with the sync, as did changing the thread queue sizes.

  


  OBS can do this, why can't I ?

  


• Extracting a bit broken AC3 audio from a video file

  3 janvier 2023, par WYSIWYG

  I Googled for about 2 hours for this problem and I can't seem to find the answer anywhere.

  


  So I have a 1080p video file which has about 2 seconds within it that's broken (at 3 minutes and 53 seconds). I found a way to extract the non-broken parts of it, also I got a replacement for the broken frames from another version of the same video (in 720p), upscaled them to 1080p and replaced them in the 1080p file (reencoding the whole file in the process). Here comes the problematic part - at the same time (3 min 53 sec), the audio is also broken and it's in Dolby Digital 5.1 AC3 format. When I try to extract the audio track from the original 1080p file and place the result in the new fixed version, which contains the upscaled video frames, the audio obviously is cut at the problematic 2 seconds and it desyncs (starts to play earlier) for the rest of the file.

  


  What I want to do and I'm unable to understand how to do it is to extract the AC3 stream in such a way that the 2 broken seconds are filled with silence and the total length of the audio stay the same as the original, so it won't desync. Is this possible and if it is, what is the correct FFMPEG command for it ?

  


  Thank you in advance.

  


  I've tried :

  


  ffmpeg -i broken.mkv -c:a copy audio.ac3

  


  which presented an output AC3 file, which is missing the 2 seconds from 03:53 to 03:55

  


  so when I combine the resulting AC3 file with the repaired video, by using :

  


  ffmpeg -i fixed.mkv -i audio.ac3 -c copy fixed-with-audio.mkv

  


  it is desynced, so at video time 03:53 I hear the audio that should play at 03:55

  


• Matomo maker InnoCraft named 2023 Hi-Tech Awards finalist

  20 avril 2023, par Erin — Press Releases

  WELLINGTON, N.Z., April 20, 2023 – InnoCraft, the makers of world-leading open-source web analytics platform Matomo, has been named an ASX Hi-Tech Emerging Company of the Year finalist in the 2023 Hi-Tech Awards. 



  Matomo founder Matthieu Aubry says, “At Matomo, we believe in empowering individuals and organizations to make informed decisions about their digital presence. By providing an open-source website analytics platform, we have created a more transparent and trustworthy digital ecosystem. We are proud to be recognised as a finalist for the Hi-Tech Awards, and we will continue to work towards a more open and ethical digital landscape, and grow the business in New Zealand and worldwide.”



  About Matomo

  Matomo, launched in 2007 as an open-source, privacy-friendly Google Analytics alternative, is trusted by over 1.5 million websites in 220 countries and has been translated in over 50 languages. Matomo tracks and analyses online visits and traffic to give users a deeper understanding of their website visitors to drive conversions and revenue ; while keeping businesses compliant with privacy laws worldwide, such as the EU’s General Data Protection Regulation (GDPR) and The California Consumer Privacy Act (CCPA).

  Aubry says Matomo is performing extremely well internationally as consumers and organizations look for privacy-focused analytics solutions, with several European countries already ruling the use of Google Analytics illegal due to data transfers to the US. In addition, Matomo’s user increase was recognized earlier this year with W3Tech’s award for the best web analytics software in its Web Technologies of the Year 2022 – with previous winners including Google Analytics and Facebook Pixel.



  A record number of companies entered the 2023 Hi-Tech Awards, with entries coming in from across the country and from all areas of the Hi-Tech sector. This depth is reflected in the line-up of finalists this year, according to David Downs, Chair of the Hi-Tech Trust, who says the standard of entries continue to grow every year.

”

  The hi-tech sector continues to flourish and it’s fantastic to see the success that so many of our companies enjoy on the international stage. This sector continues to prove its resilience and is at the forefront of our export economy in turbulent times,” says Downs.



  The Hi-Tech Awards Gala Dinner will take place on Friday, the 23rd of June, in Christchurch. 


   

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