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• ffmpeg upmix only one stream from stereo to 5.1

  24 novembre 2020, par eje211

  I'm trying to play a file in Plex without conversion. The file is H264, but, for some reason, it was incredibly slow in Plex and its playback controls showed no video stream. The info for the file in Plex did show H264. (Plex is running on a Raspberry Pi, so I want no conversion.) I converted from H264 to H264 ; sometimes that works because there's something wrong with the original H264. I didn't, so I moved to WebM.

  


  The file has two audio streams : one in 5.1 and one in stereo. I really want to keep both. Plex had no problem playing the 5.1 WebM, but for some reason, it started converting the video when stereo was selected. (I've run files with multiple audio streams with no problem on Plex before.) So I thought I could upmix the stereo to 5.1, since Plex seems to prefer it for this file. The streams in the file, in order, are : video, 5.1, stereo. I did this :

  


  ffmpeg -i "$video" \
    -filter_complex "[0:1]channelmap=channel_layout=5.1[a],[0:2]pan=5.1|FL=FL|FR=FR|LFE...$/webm/')" null


  


  (I found that channelmap=channel_layout=5.1 was required for the 5.1, oddly enough.

  


  Now, no matter how I describe the second audio stream, ffmpeg does not find it. With the code above, I get :

  


  Stream specifier ':2' in filtergraph description [0:1]channelmap=channel_layout=5.1[a],[0:2]pan=5.1|FL=FL|FR=FR|LFEcode>

  


  But [0:2] is the second audio stream. I tried [0:a:0] and [0:a:1], but ffmpeg does not recognize that. I tried specifying two -filter_complex options, one for each stream. That didn't work either.

  


  So :

  


  

  1. Is the a better way to fix my Plex problem ?

  


  2. Otherwise, how can I get ffmpeg to recognize the second audio channel in my input file ?

  


  


  Thanks !

  


• How to configure and validate a Funnel in Piwik Analytics

  16 janvier 2017, par InnoCraft — Community

  In the last blog post we have covered how the conversion Funnel plugin enriches your Piwik experience. This post will focus on how to configure and validate your funnel in Piwik so you get the correct data when you view the funnel reports. When you set up a funnel, it is crucial to have it configured correctly as the funnel report will be only as good as its configuration. When we built this Funnel feature, we focused on making the configuration and validation real simple because it is so important to get it right.

  To recap quickly : A Funnel defines a series of steps that you expect your visitors to take on their way to converting a goal or a sale. Funnels, a premium feature for Piwik developed by InnoCraft, lets you define funnels so you can improve your websites and mobile apps based on this data. Learn more about Funnel.

  Configuring a funnel

  As you will notice Funnels integrates nicely into the Piwik Goals management. You can configure a funnel whenever you create or update a goal. You can access the Goals Management either via “Administration => Goals” or via the reporting menu “Goals => Manage”. Then click on either “Add a new goal” or select an existing goal to edit it. At the bottom of the goal form, you will see a new row letting you configure a funnel. As with all our premium features we focused on displaying lots of inline help and explain directly in the UI what a funnel is about, what the steps are in order to configure a funnel, how a funnel helps you and more. This lets you use the Funnel feature even if you have never created or analyzed a funnel before.

  Preparing your Funnel configuration

  Before starting to configure a Funnel we usually have a brainstorm session identifying the funnels on a website or app and the paths we expect users to take there. Once we have identified each step, we click through those identified pages in our website and we note the URLs for each page as the URLs will be needed when you configure a funnel.

  Setting up a Goal

  Once we have finished the planning phase it is time to log into Piwik. We start by either adding a new goal or selecting an existing goal. If you are unfamiliar with setting up goals, have a look at the Piwik Goals user guide. At the bottom of a goal form when you create or update a goal, you can configure your funnel. The UI will first explain you everything about Funnels, what they are, how they help you and which steps you need to take in order to configure it.

  Configuring Funnel steps

  We start by configuring the steps we have identified in the planning phase. Those are the steps we expect our users to take when they convert a goal or purchase something. Now we need to add a step for each page we expect users to take, each step consists of a name and a pattern.

  The name will be shown to you in the funnel reporting so think of a good name that describes each step best, for example “Product”, “Cart”, “Checkout” and “Order”.

  The pattern is needed to define when a visitor will enter this step. Here it comes in handy to have already notes for each URL from the planning phase. You can select lots of different patterns based on “URL Path”, “URL” and “URL parameter”. For example “URL starts with”, “Path ends with”, “URL contains”, “URL matches the regular expression”, and more. Most tools make this configuration unnecessarily hard because they only allow you to choose from one or two patterns (only complicated pattern like regular expressions) and they don’t let you validate whether the URL you have in mind actually matches the pattern. There are three ways to validate your step configurations.

  

  Validating funnel steps

  When we configure a funnel, we validate our steps in the following three ways.

  1. Via the help icon next to the step configuration

  When you click on the help icon, you will receive valuable tips about configuring steps, what “required” means and how to match popular pages. It will also show you a list of all URLs that were tracked in your Piwik in the past and match your specified pattern. For example say you specify a pattern “Path starts with /products”, then Piwik will list all URLs that were tracked in the past matching this pattern. This lets you validate whether your pattern actually matches the URLs you had in mind. It will also show you if the pattern doesn’t match any known URL which can indicate that your configuration may be wrong.

  

  2. Via the URL validator

  Below the steps configuration you find a form field that lets you enter any URL.

  

  We recommend to enter each URL that you have noted before in the planning phase. Once you enter a URL, the configurations will be validated immediately and the result will be shown to you in the step configuration. When a step matches your specified URL, the background will become green, when a step does not match the URL, the background will be red.

  

  If the URL does not match the expected step, simply change your step configuration and the steps will be re-validated as you change the configuration. This way you will see instantly as soon as you got the configuration right.

  What you don’t want is that either all of your steps don’t match (red background) or that several steps match a certain URL (green background). When several step match one URL, then one visitor might enter several funnel steps on just one page. This usually indicates a problem with the step configuration.

  3. Manual funnel validation

  After we have created or updated the goal (more about this soon), we always test a funnel configuration manually. This means we now open our website and click through the pages that we hand in mind and check afterwards whether the steps we took actually appear in the funnel report as expected. This is just another safety net to make sure your funnel configuration is right.

  It is really crucial to have a correct funnel configuration as otherwise the shown data in the funnel reports might not be as helpful. That’s why we focused so much on making the validation part real easy.

  Activating and saving the funnel

  Once you are happy with your configuration, it is time to activate your funnel. As soon as you activate your funnel, a report for this funnel will be generated and the links and reports for this funnel will be visible in the UI. If you are later no longer interested in the funnel, simply deactivate the funnel so it won’t appear in the reporting UI anymore.

  

  To save your funnel configuration simply click on either “Add goal” or “Update goal”. The funnel will be automatically saved whenever you update your goal.

  Goals Management

  The funnel plugin also enriches the list of goals in the Piwik goal management. At a glance you can see whether a funnel for a goal is configured and activated (green tick in the funnel column), whether a funnel is configured but not activated (grey tick in the funnel column) or whether no funnel is configured for a goal (no tick at all).

  

  How to get Funnels and related features

  You can get Funnels on the Piwik Marketplace. If you want to learn more about Funnels you might be also interested in the Funnel User Guide and the Funnel FAQ.

  Similar to Funnels we also offer Users Flow which lets you visualize the flow of your users and visitors across several interactions.

• avcodec/nvdec : Round up odd width/height values

  24 novembre 2017, par Philip Langdale

  avcodec/nvdec : Round up odd width/height values
  nvdec will not produce odd width/height output, and while this is
  
  basically never an issue with most codecs, due to internal alignment
  
  requirements, you can get odd sized jpegs.
  If an odd-sized jpeg is encountered, nvdec will actually round down
  
  internally and produce output that is slightly smaller. This isn't
  
  the end of the world, as long as you know the output size doesn't
  
  match the original image resolution.
  However, with an hwaccel, we don't know. The decoder controls
  
  the reported output size and the hwaccel cannot change it. I was
  
  able to trigger an error in mpv where it tries to copy the output
  
  surface as part of rendering and triggers a cuda error because
  
  cuda knows the output frame is smaller than expected.
  To fix this, we can round up the configured width/height passed
  
  to nvdec so that the frames are always at least as large as the
  
  decoder's reported size, and data can be copied out safely.
  In this particular jpeg case, you end up with a blank (green) line
  
  at the bottom due to nvdec refusing to decode the last line, but
  
  the behaviour matches cuviddec, so it's as good as you're going to
  
  get.
  

  • [DH] libavcodec/nvdec.c