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• Using FFMPEG for Bidirectional Voice Communication with Symmetric RTP

  3 février 2024, par Batuhan Öksüz

  I am trying to make a voice communication between two peers. The first peer is my local machine which is behind a symmetric NAT. The second peer is my server running on an AWS EC2 device which has a public IP address. I want to use FFMPEG for sending the audio stream through RTP while at the same time listening to a known port to receive the audio stream the remote peer sends to my device. In order to not deal with NAT traversal issues, I want to be able to use the same IP address and port number I use for sending on my local device for receiving. Is this plausible ? I'm starting to think that this is not possible and here is my rationale :

  


  

  • If my understanding is correct UDP doesn't allow full-duplex communication ; that is, one cannot use one IP:port pair for both sending and receiving data packets at the same time. Is that correct ?

  


  • If one wants to bind a socket that is already been bound, the function throws a bind error saying "Address already in use.". I figured there is a UDP option to allow binding to the same port or address even if they are in use. These options are namely SO_REUSEADDR and SO_REUSEPORT. However, this page states that it is only possible if the port is in TIME_WAIT state. So this also supports my suspicion.

  


  


  On the other hand, there is symmetric RTP that clearly states a device can receive RTP streams from an address and port that it simultaneously uses to transmit RTP streams from. With exact words of the RFC :

  


  


  A device supports symmetric RTP if it selects, communicates, and uses
IP addresses and port numbers such that, when receiving a
bidirectional RTP media stream on UDP port "A" and IP address "a", it
also transmits RTP media for that stream from the same source UDP
port "A" and IP address "a". That is, it uses the same UDP port to
transmit and receive one RTP stream.

  


  


  


  A device that doesn't support symmetric RTP would transmit RTP from a
different port, or from a different IP address, than the port and IP
address used to receive RTP for that bidirectional media steam.

  


  


  So this is where I get confused. Is symmetric RTP somehow works around the limitations of UDP ? How am I getting this wrong ?

  


  Now going back to FFMPEG and the use of symmetric RTP, I see there is an rtp option we can use to set it up, the so called localrtpport=n. I can find almost no explanation to what it does and how it's useful though. Can anyone help me with that ? As far as I can tell, this option tells FFMPEG to use port "n" as the outbound port when transmitting an RTP stream. So if the receiver transmitted its stream to this port then the problem of symmetric NAT requirement would be resolved. Or so I thought...

  


  To draw you a better picture, here are my FFMPEG commands (I'm trying everything in my local host in these commands) :

  


  # My Mac with en0 IP of 192.168.1.64
ffmpeg \
-hide_banner \
-re \
-fflags +genpts \
-f lavfi -i aevalsrc="sin(400*2*PI*t)" \
-ar 8000 \
-f mulaw \
-f rtp -reuse 1 "rtp://192.168.1.72:9193?reuse=1&localrtpport=16386&localrtcpport=16387" \
-protocol_whitelist udp,rtp \
-i rtp://192.168.1.64:16386 \
audio_signal_with_symmetric_rtp.mp3


  


  Here I am simply generating a fixed sound signal and outputting it in mulaw format through rtp. I am using the 'localrtport' option to set my outbound port and I am expecting to receive the remote peer's stream on the same port. This command starts running and and waits for the incoming stream. As soon as I start transmitting the stream from my Raspberry Pi which is on the same wireless network, I get the dreaded "Address already in use." error and the process terminates. Here is the command I use on the Raspberry :

  


  # My Raspberry Pi with wlan0 IP of 192.168.1.72
ffmpeg \
-hide_banner \
-re \
-f lavfi -i aevalsrc="sin(400*2*PI*t)" \
-ar 8000 \
-f mulaw \
-f rtp "rtp://192.168.1.64:16386?reuse=1&localrtpport=16386"


  


  TLDR

  


  The short form of the question comes down to this : How can I make use of symmetric RTP with FFMPEG, receive a stream from the same port I am actively transmitting another stream from ? Is what I'm asking impossible ? Should I go for an alternate route and try to set up a TURN server for my system ? Any help would be appreciated.

  


• Use data to develop impactful video content

  28 septembre 2021, par Ben Erskine — Analytics Tips, Plugins

  Creating impactful video content is at the heart of what you do. How you really engage with your audience, change behaviours and influence customers to complete your digital goals. But how do you create truly impactful marketing content ? By testing, trialling, analysing and ultimately tweaking and reacting to data-informed insights that gear your content to your audience (rather than simply producing great content and shooting arrows in the dark).

  Whether you want to know how many plays your video has, finish rates, how your video is consumed over time, how video was consumed on specific days or even which locations users are viewing your video content. Media Analytics will gather all of your video data in one place and provide answers to all of these questions (and much more).

  

  What is impactful video content ?

  Impactful video content grabs your audience’s attention, keeps their attention and promotes them to take measurable action. Be that time spent on your website, goal completion or brand engagement (including following, commenting or sharing on social). Maybe you’ve developed video content, had some really great results, but not consistently, nor every time and it can be difficult to identify what exactly it is that engages and entices each and every time. And we all want to find where that lovely sweet spot is for your audience.

  Embedded video on your website can be a marketing piece that talks about the benefits of your product. Or can be educational or informative that support the brand and overall impression of the brand. And at the very best entertaining at the same time. 

  84% of people say that they’ve been convinced to buy a product or service by watching a brand’s video. Building trust, knowledge and engagement are simply quicker with video. Viewers interact more, and are engaged longer with video, they are more likely to take in the message and trust what they are seeing through educational, informative or even entertaining video marketing content than solely through reading content on a website. And even better they take action, complete goals on your website and engage with your brand (potentially long term).

  It is not only necessary to have embedded video content on your website, it needs to deliver all the elements of a well functioning website, creating the very best user experience is essential to keeping your viewers engaged. This includes ensuring the video is quick to load, on-brand, expected (in format and tone) and easy to use and/or find. Ensuring that your video content is all of these things can mean that your website users will stick around longer on your website, spend more time exploring (and reading) your website and ultimately complete more of your goals. With a great user experience, your users, in turn, are more likely to come back again to your website and trust your brand. 

  All great reasons to create impactful video content that supports your website and brand ! And to analyse data around this behaviour to repeat (or better) the video content that really hits the mark.

  

  Let’s talk stats

  In terms of video marketing, there are stats to support that viewers retain 95% of a message when they view it in a video format. The psychology behind this should be fairly obvious. It is easier (and quicker) for humans to consume video and watch someone explain something than it is to read and take action. Simply look at the rise of YouTube for explanatory and instructional video content !

  And how about the 87% of marketers that report a positive ROI on using video in their marketing ? This number has steadily increased since 2015 and matches the increase in video views over the years. This should be enough to demonstrate that video marketing is the way forward, however it needs to be the right type of video to create impact and engagement.

  Do you need more reasons to consider honing and refining your video content for your audience ? And riding this wave of impactful video marketing success ?

  

  But, how do we do that ?

  So, how do you make content that consistently converts your audience to engaged customers ? The answer is in the numbers. The data. Collecting data on each and every piece of media that is produced and put out into the world. Measuring everything, from where it is viewed, how it is viewed, how much of it is viewed and what is your viewer’s action after the fact.

  While Vimeo and YouTube have their own video analytics they are each to their own, meaning a lot more work for you to combine and analyse your data before forming insights that are useful. 

  Your data is collected by external parties, and is owned and used by these platforms, for their own means. Using Web Analytics from Matomo to collect and collate media data can mean your robust data insights are all in one place. And you own the data, keeping your data private, clean and easy to digest. 

  Once your data is across a single platform, your time can be spent on analysing the data (rather than collating) and discovering those super valuable insights. Additionally, these insights can be collated and reported, in one place, and used to inform future digital and video marketing planning. Working with the data and alongside creative teams to produce video that talks to your audience in an impactful way.

  The more data that is collected the deeper the insights. Saving time and money across a single platform and with data-backed insights to inform decisions that can influence the time (and money) spent producing video content that truly hits the mark with your audience. No more wasted investment and firing into the dark without knowledge. 

  Interrogating the ideal length of your video media means it is more likely to be viewed to the end. Or understanding the play rate on your website of any video. How often is the video played ? And which is played more often ? Constant tweaking and updating of your video content planning can be informed by data-driven human-centric insights. By consistently tracking your media, analysing and forming insights you can build upon past work, and create a fuller picture of who your audience is and how they will engage with future video content. Understanding your media over time can lead to informed decisions that can impact the video content and the level of investment to deliver ROI that means something.

  

  Wrap Up

  Media Analytics puts you at the heart of video engagement. No more guessing at what your audience wants to see, how long or when. Make every piece of video content have the impact you want (and need) to drive engagement, goal completion and customer conversion. Create a user experience that keeps your users on your website for longer. Delivering on all of those delicious digital marketing goals and speaking the language of key stakeholders throughout the business. Back your digital marketing, with truly impactful content, and above all else deliver to your audience content that keeps them engaged and coming back for more.

  Don’t just take our word for it ! Take a look at what Matomo can offer you with streamlined and insightful Media Analytics, all in one place. And go forth and create impactful content, that matters.

  Next steps :

  Check out our detailed user guide to Media Analytics

  Or, if you have questions, see our helpful Video & Audio Analytics FAQ’s

• ffmpeg, live MPEG-TS demux & decode

  8 mai 2017, par NadavRub

  Environment

  • Ubuntu-14
  • C++
  • ffmpeg

  Use-case

  • Live SPTS is received via UDP by a 3rd party module
  • TS Packets are received iteratively
  • The TS Video (ES) should be decoded in minimal latency

  Considered Implementation

  • Upon TS packet reception, immediately push it to the TS demux
  • Once enough packets are received the video format is resolvable, create the video codec
  • Push each video packet into the video decoder
  • Once enough video packets were processed the video codec result a valid output frame

  Problem at-hand

  Can this be done w/ ffmpeg ?!?!, … using “avformat_open_input” mandate a file to read from… I need a way where I can iteratively push packets to the TS demuxer ( w/ minimal latency )…

  Does ffmpeg support the above mentioned use-case ? How ?