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• Precisely trim a video with ffmpeg

  14 août 2021, par user16665676

  I want to precisely trim a video using ffmpeg (between keyframes), while keeping the original quality and audio in sync. I understand that using -c copy will do this and re-encoding is necessary. Rather than re-encoding the entire trim duration, I have a solution :

  


  assuming the following :

  


  

  • trim start is 00:00:10

  


  • trim end is 00:00:20

  


  • closest keyframe to trim start is 00:00:10.5

  


  


  trim from the specified start to the first keyframe (keyframes are provided by ffprobe) :

  


  ffmpeg -ss 00:00:10 -i input.mp4 -t 0.5 -enc_timebase -1 -vsync 2 1.mp4

  


  -enc_timebase -1 -vsync 2 are necessary otherwise 2.mp4 has a much slower playback speed (though audio remains the same and subsequently finishes much sooner than the video).

  


  trim, using -c copy, from the keyframe above to the end time :

  


  ffmpeg -ss 00:00:10.5 -t 00:00:09.5 input.mp4 -c copy 2.mp4

  


  finally, concatenate both of the videos :

  


  ffmpeg -f concat -i input.txt -c copy output.mp4

  


  This process works great and is quick as I'm only re-encoding up to the first keyframe (usually less than a second). However, when concatenating both the trimmed (1.mp4) and copied (2.mp4) there is a noticeable jitter (in both audio and video) on the concatenated output where the first keyframe starts.

  


  After extracting each individual frame from both videos, its evident that the keyframe is being included twice, once at the end of the trimmed (1.mp4) and once at the start of the copied (2.mp4). Also, if I don't include -enc_timebase -1 -vsync 2 and the output is played back in "slow motion" on the copied (2.mp4) part of the output, the first keyframe is on screen for much longer than the others. I believe this to be the cause.

  


  Is there a better way to do this process ? Am I messing up any timings/syncing ? I'm not entirely sure if the -enc_timebase -1 -vsync 2 are the right options to use.

  


• How you can use the Piwik AOM plugin to improve your data and make better online marketing decisions

  13 septembre 2017, par André Kolell — Plugins, AdWords, Bing, Case Study, Criteo, eccommerce tracking, Facebook Ads, how to install piwik analytics, how-to piwik, integration, piwik, Taboola

  Hi, this is André, one of the authors of the Piwik Advanced Online Marketing plugin, which has just hit 5,000 downloads on the Piwik marketplace. In this blog post I’ll show you how Piwik AOM improves your data and enables you to make better online marketing decisions.

  Piwik itself is excellent in tracking all kinds of visitor data, like where a visitor is coming from and what he’s doing on your page or app (pageviews, events, conversions). But what Piwik did not yet take a closer a look at, is how much you’ve invested into your marketing activities and how profitable they are.

  With the Piwik AOM plugin you can integrate data like advertising costs, advertising campaign names, ad impressions etc. from advertising platforms (such as Google AdWords, Microsoft Bing, Criteo, Facebook Ads and Taboola) and individual campaigns (such as such as cost per view/click/acquisition and fixed price per months deals) into Piwik and combine that data with individual Piwik visits.

  Piwik AOM adds a new marketing performance report to Piwik giving you a great overview of all your marketing activities with drill-down functionality :

  

   

  When taking a look at a specific visitor, Piwik AOM shows you the exact cost of acquiring a specific visit :

  

   

  Leveraging Piwik AOM’s full potential

  But although you can access Piwik AOM’s valuable data directly in the Piwik UI for ad-hoc analyses, Piwik AOM’s true strength comes into play when working with the raw data in an external business intelligence application of your choice, where you can further integrate Piwik AOM’s data with your most accurate backend data (like conversion’s contribution margins after returns, new vs. existing customer, etc.).

  Piwik AOM offers some API endpoints that allow you to fetch the data you need but you can also retrieve it directly from Piwik AOM’s aom_visits table, which includes all visits, all allocated advertising costs and advertising campaign details. As there is never data being deleted from aom_visits, the table can easily be connected to your ETL tool with its last update timestamp column. A third way to get data out of Piwik AOM is by developing your own Piwik plugin and listening to the AOM.aomVisitAddedOrUpdated event, which is posted whenever an aom_visits record is added or updated.

  Integrating Piwik AOM’s data with your backend data in the business intelligence application of your choice allows you to evaluate the real performance of your online marketing campaigns when applying different conversion attribution models, conduct customer journey analyses, create sophisticated forecasts and whatever you can think of.

  AOM Use case

  A company that followed this approach, is FINANZCHECK.de, one of Germany’s leading loan comparison websites. At the eMetrics summit 2016 in Berlin, Germany, I gave a talk about FINANZCHECK’s architectural online marketing setup. Until recently, FINANZCHECK used Pentaho data integration to integrate data from Piwik, Piwik AOM and additional internal tools like its proprietary CRM software into Jaspersoft, its data warehouse an BI solution. The enriched data in Jaspersoft was not only used for reporting to various stakeholders but also for optimising all kinds of marketing activities (e.g. bids for individual keywords in Google AdWords) and proactive alerting. Not long ago, FINANZCHECK started an initiative to improve its setup even further – I’ll hopefully be able to cover this in a more detailed case study soon.

  Roadmap

  In the past, we had the chance to make great progress in developing this plugin by solving specific requirements of different companies who use Piwik AOM. During the next months, we plan to integrate more advertising platforms, reimplement Facebook Ads, improve the support of individual campaigns and work on the general plugin stability and performance.

  Before you install Piwik AOM

  Before installing Piwik AOM, you should know that its initial setup and even its maintenance can be quite complex. Piwik AOM will heavily modify your Piwik installation and you will only benefit from Piwik AOM if you are willing to invest quite some time into it.

  If you are not familiar with Piwik’s internals, PHP, MySQL, database backups, cronjobs, creating API accounts at the advertising platforms or adding parameters to your advertising campaign’s URLs, you should probably not install it on your own (at least not in your production environment).

  Piwik AOM has successfully been tested with up to 25k visitors a day for a period of more than two years, running on an AWS server with 4 GB RAM, once CPU and a separate AWS RDS MySQL database.

  Ideas and Support

  If you have ideas for new features or need support with your Piwik AOM installation or leveraging your marketing data’s potential in general, feel free to get in touch with the plugin’s co-author Daniel or me. You can find our contact details on the plugin’s website http://www.advanced-online-marketing.com.

  How to get the Piwik AOM plugin ?

  The Piwik AOM plugin is freely available through the Piwik marketplace at https://plugins.piwik.org/AOM

  Did you like this article ? If yes do not hesitate to share it or give your feedback about the topic you would like us to write about.

• Higher quality of JPEG frames extracted with FFMPEG from MP4 video [on hold]

  5 juin 2019, par 2006pmach

  I got a 4k mp4 video file and my goal is to extract the individual frames. Unfortunately, the video is quite big 10GB and storing all the frames lossless (e.g. using png, results in 12MB per frame) is not an option. Therefore, I tired to save directly JPEG images. For me quality is more important than a small file size around 1MB would be good.
  To do so I used FFMPEG as follows :

  ffmpeg -ss 00:04:52 -i video.MP4 -qscale:v $quality -frames:v 1 output-$quality.jpg

  I tried the full range from 2 to 31 for $quality and obtained the blue curve in the plot (PSNR vs. File size)

  Additionally, I extracted the frame and saved it as PNG and used convert from ImageMagick to compress the PNG file as follows :

  convert -quality $quality% frame.png output-$quality.jpg

  Again I tried the full range for $quality from 10 to 100 and obtained the orange line in the plot (The highest quality is 50dB but uses 6MB, so I only show the results up to 2MB).

  Now, my questions are as follows. Why is the quality of ffmpeg that much worse than when using ImageMagick ? Is it possible to increase the quality of the JPEG frames using ffmpeg directly or do I need to go via the PNG and then to JPEG. The later method is somehow suboptimal because it requires storing the png and will be much slower. Any suggestions ? My guess is that ffmpeg trades quality vs. speed...