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• Metadict in ffmpeg does not have rotate information

  14 juillet 2022, par Lucky Sunda

  My aim is to extract frames out of a video but many times the frames are inverted. This is happening because "VideoCapture" in cv2 does read the rotate flag data present in the video metadata. I am running it on mac and installed "ffmpeg" package (5.0.1) using brew package manager. This is my code to check rotation present in a video using ffmpeg.

  


  import ffmpeg 
import cv2   
import pprint 
pp = pprint.PrettyPrinter(depth=4)
def check_rotation(path_video_file):
    # this returns meta-data of the video file in form of a dictionary
    meta_dict = ffmpeg.probe(path_video_file)
    pp.pprint(meta_dict)

    # from the dictionary, meta_dict['streams'][0]['tags']['rotate'] is the key
    # we are looking for
    rotateCode = None
    if int(meta_dict['streams'][0]['tags']['rotate']) == 90:
        rotateCode = cv2.ROTATE_90_CLOCKWISE
    elif int(meta_dict['streams'][0]['tags']['rotate']) == 180:
        rotateCode = cv2.ROTATE_180
    elif int(meta_dict['streams'][0]['tags']['rotate']) == 270:
        rotateCode = cv2.ROTATE_90_COUNTERCLOCKWISE

    return rotateCode



  


  Here the meta_dict is supposed to have information about the rotation but it is not there.
printing out meta_dict gives :

  


  {'format': {'bit_rate': '18498544',
            'duration': '3.584000',
            'filename': 'video.mp4',
            'format_long_name': 'QuickTime / MOV',
            'format_name': 'mov,mp4,m4a,3gp,3g2,mj2',
            'nb_programs': 0,
            'nb_streams': 2,
            'probe_score': 100,
            'size': '8287348',
            'start_time': '0.000000',
            'tags': {'com.android.version': '11',
                     'compatible_brands': 'isommp42',
                     'creation_time': '2021-12-08T10:56:57.000000Z',
                     'major_brand': 'mp42',
                     'minor_version': '0'}},
 'streams': [{'avg_frame_rate': '990000/34997',
              'bit_rate': '18804651',
              'bits_per_raw_sample': '8',
              'chroma_location': 'left',
              'closed_captions': 0,
              'codec_long_name': 'H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10',
              'codec_name': 'h264',
              'codec_tag': '0x31637661',
              'codec_tag_string': 'avc1',
              'codec_type': 'video',
              'coded_height': 1080,
              'coded_width': 1920,
              'color_primaries': 'bt470bg',
              'color_range': 'pc',
              'color_space': 'bt470bg',
              'color_transfer': 'smpte170m',
              'display_aspect_ratio': '16:9',
              'disposition': {'attached_pic': 0,
                              'captions': 0,
                              'clean_effects': 0,
                              'comment': 0,
                              'default': 1,
                              'dependent': 0,
                              'descriptions': 0,
                              'dub': 0,
                              'forced': 0,
                              'hearing_impaired': 0,
                              'karaoke': 0,
                              'lyrics': 0,
                              'metadata': 0,
                              'original': 0,
                              'still_image': 0,
                              'timed_thumbnails': 0,
                              'visual_impaired': 0},
              'duration': '3.499700',
              'duration_ts': 314973,
              'extradata_size': 35,
              'field_order': 'progressive',
              'film_grain': 0,
              'has_b_frames': 0,
              'height': 1080,
              'id': '0x1',
              'index': 0,
              'is_avc': 'true',
              'level': 40,
              'nal_length_size': '4',
              'nb_frames': '99',
              'pix_fmt': 'yuvj420p',
              'profile': 'High',
              'r_frame_rate': '120/1',
              'refs': 1,
              'sample_aspect_ratio': '1:1',
              'side_data_list': [{...}],
              'start_pts': 3168,
              'start_time': '0.035200',
              'tags': {'creation_time': '2021-12-08T10:56:57.000000Z',
                       'handler_name': 'VideoHandle',
                       'language': 'eng',
                       'vendor_id': '[0][0][0][0]'},
              'time_base': '1/90000',
              'width': 1920},
             {'avg_frame_rate': '0/0',
              'bit_rate': '128986',
              'bits_per_sample': 0,
              'channel_layout': 'stereo',
              'channels': 2,
              'codec_long_name': 'AAC (Advanced Audio Coding)',
              'codec_name': 'aac',
              'codec_tag': '0x6134706d',
              'codec_tag_string': 'mp4a',
              'codec_type': 'audio',
              'disposition': {'attached_pic': 0,
                              'captions': 0,
                              'clean_effects': 0,
                              'comment': 0,
                              'default': 1,
                              'dependent': 0,
                              'descriptions': 0,
                              'dub': 0,
                              'forced': 0,
                              'hearing_impaired': 0,
                              'karaoke': 0,
                              'lyrics': 0,
                              'metadata': 0,
                              'original': 0,
                              'still_image': 0,
                              'timed_thumbnails': 0,
                              'visual_impaired': 0},
              'duration': '3.584000',
              'duration_ts': 172032,
              'extradata_size': 2,
              'id': '0x2',
              'index': 1,
              'nb_frames': '168',
              'profile': 'LC',
              'r_frame_rate': '0/0',
              'sample_fmt': 'fltp',
              'sample_rate': '48000',
              'start_pts': 0,
              'start_time': '0.000000',
              'tags': {'creation_time': '2021-12-08T10:56:57.000000Z',
                       'handler_name': 'SoundHandle',
                       'language': 'eng',
                       'vendor_id': '[0][0][0][0]'},
              'time_base': '1/48000'}]}


  


  Can someone please help me to find if rotation is present in a video ?

  


• Unmapping memory-mapped images that are created during processing

  23 avril 2013, par user2309283

  I have a pretty big issue, although I only have the symptoms, and a theory on the cause.

  I have a C++ application under Windows 7x64 that uses system calls to FFMPEG 0.7.13 to extract frames from videos. When running, the parent application maintains a nice, predicable memory footprint in memory profilers (task manager, RAMMap) of about 2MB. I can see the individual calls to FFMPEG also come and go without incident. The trouble is, after about 100 calls to FFMPEG, and 70,000+ PNGs created (no one directory has more than 1500 pngs), the Windows memory page size raises gradually from about 2.5GB to over 7.0GB, and the system is brought to its knees. The sum of the processes for all users is no where near the reported Memory Page amount.

  I thought it might be Windows Search indexing related, so I turned off the indexing for the output directories in question using SetFileAttributes() and FILE_ATTRIBUTE_NOT_CONTENT_INDEXED, and while it seems to be working as advertised, it does not seem to combat the issue at hand. My current running theory is that all of these extracted PNGs are either fully or partially memory mapped, by FFMPEG or something else. I can also see the output PNGs under the RAMMap Physical Pages tab as standby mapped files.

  Question :
   Is there enough information here to possibly diagnose the exact problem ?
   Do I have a way to combat this issue ?

  Thanks in advance...

• How to Use Web Analytics to Improve SEO

  5 janvier 2022, par erin — Analytics Tips

  Everyone wants their website to rank highly in Google — and that’s exactly why the world of SEO is so competitive.

  In order to succeed in such a crowded space, it’s essential to equip yourself with the right tools and processes to ensure your website is maximally optimised for search engines.

  If you’d like to improve your website’s SEO rankings, leveraging web analytics is one of the best places to start. Web analytics provides valuable insights to help you assess performance, user behaviour and optimisation opportunities.

  In this blog, we’ll cover :

  The basics of SEO and web analytics

  Before we discuss how to use web analytics for SEO, let’s start with a quick explanation of both.

  SEO (Search Engine Optimisation) encompasses a broad set of activities aimed at increasing a website’s position in search engine results pages (SERPs). When a user enters a query (e.g. ‘marketing agencies in Dallas’) in a search engine, the websites that appear near the top of the page are optimised for search engines and therefore ranking for that particular term. 

  Web analytics refers to the monitoring/assessment of metrics that track traffic sources and user behaviour on a website. This involves the use of a web analytics tool to collect, aggregate, organise and visualise website data so that meaningful conclusions can be drawn.

  The importance of website analytics for SEO

  SEO revolves around search engine algorithms – a set of rules that dictates a website’s ranking for a given search query (i.e. keyword). The algorithm takes numerous factors into account to determine a particular site’s SERP ranking. So, to achieve strong SEO, your website needs to exhibit qualities that the algorithm deems important. That’s where web analytics comes into play.

  Web analytics allows you to track key metrics and data points that affect how the algorithm ranks your website. For example, how much time do users spend on your site ? Which external links are referring traffic to your site ? How do your site’s Core Web Vitals stack up ? 

  Understanding this data will supply you with the insights needed to make positive adjustments, ultimately improving your website’s SEO. 

  How do you analyse a website for SEO ?

  The SEO analysis of a website needs to be focused on relevant data that’s applicable to search engine rankings. When conducting your website SEO analysis, here are some notable metrics and data fields to pay attention to :

  1. Bounce rate and dwell time

  These metrics denote how much time users spend on your website. If users frequently exit your site after only a few seconds, Google may view this as a negative indicator. To reduce bounce rate and increase dwell time, you should work towards making your site’s content more captivating and ensuring that there aren’t any technical issues with your site (e.g. pages taking too long to load or not optimised for mobile).

  

  2. Broken/dead links

  Perform a technical analysis to scan your website for faulty links. If your site contains broken links that lead to 404 pages, this can detract from your website’s SEO rankings. Redirect those links to a related page or remove them.

  

  Matomo’s Crawling Errors report can give you instant access to this technical information so you can resolve it before it begins to impact your ranking.

  3. Scroll depth

  Measuring scroll depth (how far users scroll down the page) can help you gauge the quality of your content — and this goes hand-in-hand with bounce rate and dwell time. To assess scroll depth, you can use a Tag Manager to track the specific scroll percentage on your site’s pages.

  4. Transitions

  Studying how users transition from page to page within your site can help you understand their behaviour more holistically. Which pages do they tend to gravitate towards ? Are there CTAs on your blog that aren’t driving many click-throughs ? Optimising user journeys will, in turn, elevate the overall user experience on your site.

  

  5. Internal site search

  You can use site search tracking and reporting to learn what your audience is looking for. If you notice a trend (e.g. the majority of searches are for pricing because your pricing page isn’t in the navigation menu), this can inform both site architecture and content planning.

  

  Ecommerce sites in particular should be monitoring branded queries, especially in regards to brand misspellings that could be causing users to bounce off the site.

  6. Segments

  Separating your visitors into distinct segments can produce granular insights that paint a more accurate picture.

  For example, perhaps you notice that your bounce rate is far higher on mobile, or with users from the UK. In both cases, this knowledge will provide clarity on where to focus your optimisation efforts (e.g. mobile responsiveness, UK-specific content/landing pages, etc.).

  

  7. Acquisition channels

  It’s crucial to analyse where your website traffic is coming from. Among other things, reviewing your acquisition metrics will reveal which external websites are referring the most traffic to your website. 

  Links from external sites (also known as backlinks) are one of the most important ranking factors because this tells Google that your site is reputable and credible. So, you may choose to cultivate a relationship with these sites (or similar sites) by offering guest blogging and other link building initiatives.

  

  In addition to the above, you should also be monitoring your Core Web Vitals — which leads us to our next section.

  What are Core Web Vitals and why are they important ?

  Core Web Vitals are a set of 3 primary metrics that reflect the general user experience of a website. These metrics are load time, interactivity and stability. 

  1. Load time (LCP) refers to the amount of time it takes for your website’s text and images to load.
  2. Interactivity (FID) refers to the amount of time it takes for user input areas (buttons, form fields, etc.) to become functional.
  3. Stability (CLS) refers to the visual/spatial integrity of your website. If text, images, and other elements tend to suddenly shift position when a user is viewing the site, this will hurt your CLS score.

  

  So, why are these Core Web Vitals metrics important for SEO ? Generally speaking, Google prioritises user experience — and Core Web Vitals affect users’ satisfaction with a website. Furthermore, Google has confirmed that Core Web Vitals are, indeed, a ranking factor.

  Matomo enables you to track metrics for Core Web Vitals which we refer to as SEO Web Vitals.

  How to measure and track keyword performance

  We can’t talk about SEO and analytics without touching on keywords. Keywords (the words/phrases that users type in a search engine) are arguably the most cardinal component of SEO. So, outside of website performance, it’s also necessary to track the keywords your website is ranking for. 

  Recall from above that SEO is all about ranking highly on SERPs for certain search queries (i.e. keywords). To assess your Search Engine Keyword Performance, you can use an analytics tool to view Keyword reports for your website. These reports will show you which keywords your site ranks for, the average SERP position your site achieves for each keyword, the amount of traffic you receive from each keyword, and more.

  

  Digging into your keyword performance can help you identify valuable keyword opportunities and improvement goals.

  For example, upon reviewing your highest-traffic keywords, you may choose to create more blog content around those keywords to bolster your success. Or, perhaps you notice that your average position for a high-intent keyword is quite low. In that case, you could implement a targeted link building campaign to help boost your ranking for that keyword. 

  Final thoughts

  In this article, we’ve discussed the benefits of web analytics — particularly in regards to SEO. When it comes to selecting a web analytics tool, Google Analytics is by far the most popular choice. But that doesn’t make it the best.

  At Matomo, we’re committed to providing a superior alternative to Google Analytics. Matomo is a powerful, open-source web analytics platform that gives you 100% data ownership — protecting both your data and your customers’ privacy.

  Try our live demo or start a free 21-day trial now – no credit card required.