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• How do I change the speed of an audio file in Python, like in Audacity, without quality loss ?

  23 août 2023, par Somnia Quia

  I'm building a simple Python application that involves altering the speed of an audio track.
(I acknowledge that changing the framerate of an audio also make pitch appear different, and I do not care about pitch of the audio being altered).
I have tried using solution from abhi krishnan using pydub, which looks like this.

  


  from pydub import AudioSegment
sound = AudioSegment.from_file(…)

def speed_change(sound, speed=1.0):
    # Manually override the frame_rate. This tells the computer how many
    # samples to play per second
    sound_with_altered_frame_rate = sound._spawn(sound.raw_data, overrides={
         "frame_rate": int(sound.frame_rate * speed)
      })
     # convert the sound with altered frame rate to a standard frame rate
     # so that regular playback programs will work right. They often only
     # know how to play audio at standard frame rate (like 44.1k)
    return sound_with_altered_frame_rate.set_frame_rate(sound.frame_rate)


  


  However, the audio with changed speed sounds distorted, or crackled, which would not be heard with using Audacity to do the same, and I hope I find out a way to reproduce in Python how Audacity (or other digital audio editors) changes the speed of audio tracks.

  


  I presume that the quality loss is caused by the original audio having low framerate, which is 8kHz, and that .set_frame_rate(sound.frame_rate) tries to sample points of the audio with altered speed in the original, low framerate. Simple attempts of setting the framerate of the original audio or the one with altered framerate, and the one that were to be exported didn't work out.

  


  Is there a way in Pydub or in other Python modules that perform the task in the same way Audacity does ?

  


• fixing (with ffmpeg) the chrominance position on a video after capturing

  23 mai 2016, par APLU

  I’m trying to convert some video from VHS to digital using an (old) video capture card (and obviously an old VHS player). Due to the input from my video capture card and the output available from the VHS, I have no other choice than capture with an S-Video cable to a computer.

  Almost everything works except a little mis-synchronization between chroma and luma which do not happen on TV.

  For example, in the original video, I have something like that :
  

  After capturing the video looks like this :
  

  As you may see, there is a little desynchronization of the chroma with the luma channel (I will say about 10 lines errors).

  I’m capturing with ffmpeg on a Linux system with the following commands :

  $ v4lctl setnorm PAL-BG

  $ v4lctl setinput S-video

  $ ffmpeg -y -f alsa -ac 2 -i pulse -f video4linux2 -i /dev/video0 -c:a pcm_s16le -vcodec rawvideo -t $duration -r 25 -loglevel error -stats /tmp/tmp.mkv

  I tried other input norm in v4l, tried an other VHS player, tried an other conversion cable from SCART to S-Video but it didn’t change anything,

  My question is simple : is there a way to fix this with a post-processing video filter in ffmpeg ?

  I already looked at the long list of video filter available in ffmpeg but I didn’t find anything.

  Also, please note I can’t apply filter during the capture commands (old capture cards, old cpu, ..), this is why I capture in rawvideo and native audio. When the capture is done I convert the video/audio into h264/vorbis, at this step I can apply as much as audio/video filtering needed (even if it include extracting chroma & luma to new files, fixing and merging again).

  Thanks !

• iOS 17’s Impact on Marketing : Navigating Privacy Changes

  22 septembre 2023, par Erin — Analytics Tips, Marketing

  In the ever-evolving landscape of digital marketing, staying up-to-date with the latest changes is paramount. One such significant change came on 18 September 2023, in the form of iOS 17, Apple’s latest operating system update. With iOS 17, Apple has introduced new privacy features that are set to have a profound impact on marketers and how they track and analyse user behaviour. 

  In this blog, we will explore what iOS 17 is, how it affects tracking, which tracking parameters are impacted, what remains unaffected, and most importantly, how marketers can future-proof their campaign tracking URLs.

  What is iOS 17 ?

  iOS 17 is the latest update to Apple’s mobile operating system, used on millions of iPhones worldwide. While iOS updates often bring new features and improvements, iOS 17 has made waves in the digital marketing community due to its emphasis on user privacy.

  How does iOS 17 affect tracking ?

  One of the key features of iOS 17 that concerns marketers is its impact on tracking. Apple’s new update aims to enhance user privacy by limiting the information that can be tracked and collected by third-party entities, particularly through query parameters in URLs. This means that certain tracking mechanisms that marketers have relied on for years are now rendered ineffective on iOS 17 devices.

  Campaign tracking URLs, also known as tracking parameters or UTM parameters, are special codes added to the end of URLs. They are used by marketers to track various aspects of a user’s interaction with a digital marketing campaign. These parameters provide valuable data, such as the source of traffic, the medium through which users arrived and specific campaign details.

  For example, with Matomo (mtm) tracking parameters, a campaign tracking URL might look like this :

  https://www.example.com/products/example_product?mtm_campaign=summer-sale

  

  Understanding the impact of iOS 17 on campaign tracking URLs is essential for marketers who rely on this data to measure the effectiveness of their marketing campaigns.

  Which campaign tracking parameters are affected by iOS 17 ?

  Several tracking parameters commonly used by marketers will no longer work as expected on iOS 17. Some of these include :

  • Facebook (fbclid) : Employed for tracking Facebook advertising campaigns. 
  • Instagram (igshid) : Used to track user interactions with Instagram ads.
  • Google Ads (gclid) : Used to track Google Ads campaigns. 
  • Twitter (twclid) : Used to track user interactions with Twitter ads. 
  • Microsoft Ads (msclkid) : Employed for tracking Microsoft Ads campaigns. 
  • Mailchimp (mc_eid) : Used by Mailchimp for email campaign tracking. 

  These changes are significant, as they disrupt many of the common tracking methods that marketers rely on to measure the effectiveness of their campaigns.

  Which campaign tracking parameters are not affected by iOS 17 ?

  While many tracking parameters have been impacted, there are still some that remain unaffected on iOS 17. However, it’s important to note that the status of these parameters might change in the future as Apple continues to prioritise user privacy. Some of the tracking parameters that are still working as of now include :

  • Matomo (mtm) : Matomo campaign tracking parameters. 
  • Google Analytics (UTMs) : Google Analytics campaign tracking parameters.
  • Pinterest (epik) : Used for tracking Pinterest campaigns. 
  • Klaviyo (_kx) : Klaviyo for email marketing tracking. 
  • TikTok (tt-) : Used for tracking TikTok ad interactions. 
  • Hubspot (hsa) : Used for tracking Hubspot campaigns. 

  While these parameters offer some reprieve for marketers, it’s essential to keep a close eye on any potential changes in their functionality as Apple continues to roll out privacy-friendly features.

  How are Matomo users impacted ?

  Fortunately, Matomo, as a leading privacy-friendly web analytics solution, remains unaffected by the changes introduced by iOS 17. Specifically :

  For Matomo users who rely on mtm or UTMs

  If you’re using Matomo or GA tracking parameters, you can rest assured that iOS 17’s changes won’t affect your tracking capabilities in Matomo.

  Attention to gclids (Google Ads) and msclkid (Bing Ads)

  If you use Google Ads or Bing Ads tracking parameters with Matomo’s Advertising Conversion Export feature for tracking, iOS 17 presents a challenge. Your gclids and msclkids may not provide the same level of tracking accuracy on Apple mobile devices. This is a critical consideration, especially if your ad campaigns target mobile users.

  To stay informed about changes in the digital marketing landscape, including updates related to iOS 17, sign up for our newsletter where we regularly provide updates and insights on adapting your tracking and marketing strategies to ensure compliance and respect user privacy.

  How to future-proof your campaign tracking

  Given the impact of iOS 17 on tracking, it’s crucial for marketers to adapt and future-proof their campaign tracking strategies. Here are some steps you can take to mitigate the affects of iOS 17 on your marketing campaigns :

  Monitor platform updates

  Expect updates from advertising and analytics platforms in response to Apple’s privacy changes. These platforms are likely to develop alternative tracking methods or adapt existing ones to comply with iOS 17’s restrictions. Stay informed about these updates and incorporate them into your tracking strategy.

  Prioritise privacy-friendly tech stacks

  In the ever-evolving digital marketing landscape, it’s crucial to prioritise privacy-friendly tech stacks. Privacy-friendly tracking tools like Matomo are essential for maintaining trust and respecting user privacy.

  Matomo ensures the privacy of your users and analytics data. When using Matomo, you retain control of your data ; nobody else does. This commitment to user privacy aligns with the changing digital marketing landscape, where privacy is taking centre stage.

  Transition from affected campaign tracking parameters

  If you’ve been using tools like Mailchimp, whose campaign tracking URLs have been affected by iOS 17, consider transitioning to the campaign tracking URL parameters of your analytics solution. Whether you choose Matomo or Google Analytics, these solutions can help you understand how your email marketing campaigns are performing.

  Focus on data privacy compliance

  Embrace data privacy compliance practices. As privacy regulations evolve, it’s essential to prioritise transparency in data collection. Ensure that your tracking methods align with privacy standards to maintain trust with your audience.

  Regularly review and adapt

  The digital marketing landscape is dynamic, and iOS 17 is just one example of how quickly things can change. Regularly review your tracking methods and adapt to new developments in the industry. Staying agile and informed is key to long-term success.

  Marketers’ path forward

  iOS 17 has reshaped mobile user privacy, challenging marketers to adapt. While some tracking parameters are affected, savvy marketers can still thrive by embracing unique tracking solutions, staying informed about platform updates, and prioritising data privacy. 

  Explore Matomo for privacy-friendly analytics and navigate this evolving landscape successfully with our 21-day free trial – no credit card required.