August 23, 2019

Streaming Media Readers' Choice Awards 2019

Streaming Media magazine has started a vote for Readers' Choice Awards 2019.

Softvelum products have been nominated in 6 categories:

  • Analytics/Quality of Service Platform - Softvelum Qosifire
  • Encoding Software - Softvelum Nimble Live Transcoder 
  • Media Server - Softvelum Nimble Streamer
  • Quality Control/Monitoring Platform - Softvelum Qosifire
  • Server-Side Ad Insertion Solution - Softvelum Nimble Advertizer
  • Video Player Solution/SDK - Softvelum SLDP Player

Open the voting page and select our products to vote as shown on a screenshot below. Voting closes on 1st of October. At that point, all voters will receive an email asking them to to confirm their votes and only the confirmed votes will be counted.

Your support is very important for our team, so have a minute to cast your vote for us!

Here's how you can find us in a huge list of nominations and nominees:

Feel free to support our team, every vote matters!

August 21, 2019

Live Transcoder upgrade

Nimble Streamer Live Transcoder was released in early 2016 and since then it has got many useful features which our customers use widely. The core technology of the Transcoder combines both Softvelum team's own know-how and third-parties' work. Those third parties are listed on a corresponding page.

As we add new functionality, some core third-party technologies also advance forward. For instance, FFmpeg which is used for filtering and some decoding operations, has moved from version 3 to version 4, getting some important fixes and improvements. So in order to keep pace with FFmpeg, our team had to make adjustments and use latest version 4.

New FFmpeg version requires changes in both Nimble Streamer and Live Transcoder. So if you decide to make upgrade of Nimble Streamer then, in order to make smooth transition among versions, Nimble and Transcoder packages will have to be upgraded simultaneously. If one of the packages is upgraded without its counterpart, then live transcoding will stop working.

So here is what you need to do in order to complete this upgrade the correct way.

For Ubuntu, run this command
sudo apt-get update
sudo apt-get install nimble nimble-transcoder

For Debian, run this command
apt-get update
apt-get install nimble nimble-transcoder

For CentOS, run this command
sudo yum makecache
sudo yum install nimble nimble-transcoder

You may also run procedures from Live Transcoder upgrade page first and then Nimble Streamer upgrade page one after another do get the same result. If you have Windows, you also need to follow this path.

So we recommend you to perform this simultaneous upgrade when you have time and resource for that.

After the upgrade is complete, your Nimble Streamer package version will be 3.6.0-1 and Live Transcoder package version will be 1.1.0-1.

If you have any questions or face any issues during the upgrade, please contact us using our helpdesk.

August 20, 2019

Trigger SCTE-35 marker insertion into live stream

Nimble Advertizer has wide variety of options to insert ads, including inserting ads per SCTE-35 markers. So if your original stream has those markers and your Advertizer is set up to trigger ads for it, your output will have proper ads.

In addition to reacting to available SCTE-35 markers, Nimble Advertizer is able to insert new markers right at the moment you need them using Nimble API. This will trigger almost immediate ads insertion so it's a good way to implement your own "big red button" for per-request ads insertion. Here's how you can do it.

Set up Advertizer

SCTE-35 insertion feature set is part of Nimble Advertizer. So first you need to create and subscribe for Advertizer license.

Then you need to set up Advertizer according to Advertizer tech spec. This includes preparation of ads files and setup configuration. As part the setup, you'll define what streams will be reacting to markers. You can read article explaining SCTE-35 markers handling mechanics, including example of handler response.

Set up Nimble API

Markers insertion is performed via Nimble native API. Use this API page to enable API first and then get familiar with "Insert SCTE-35 marker" call. Try to call that method on some test streams to see how it triggers the insertion of ads.

Use markers insertion

Once you have your Advertizer ready for markers handling and know how to use proper API call, you may develop further setup for triggering ads via API call in your production environment.

Besides immediate insertion via Advertizer, you may pass through the inserted SCTE-35 markers for further processing. Read this article for details of this functionality.

If you find any issues with SCTE-35 feature set, please file us a support ticket so we could help you.

Related documentation

Nimble Advertizer, Inserting ads via SCTE-35 markersNimble Streamer live streaming scenarios, SCTE-35 markers passthrough

August 15, 2019

ABR in SLDP real-time streaming

Streaming media industry currently moves away from RTMP protocol to other real-time streaming technologies due to its future decline. The next generation of technologies tries not just to replace the protocol but also add new features like ABR or new codecs support.

Our team introduced SLDP - Softvelum Low Delay Protocol - as our vision of how real-time streaming should be implemented. Of course, we added capabilities that were missing in RTMP.

ABR capabilities

Adaptive bitrate (ABR) is one of the key features available as part of SLDP. It's supported on both sides of transmission:
  • Nimble Streamer server allows switching per player command among available bitrates which are set up as part of ABR stream
  • SLDP Player provides controls for switching between bitrates if a stream has information about available sub-streams.
Switching of channels may be performed nearly instantly. A player sends command to a server to send media from another bitrate and once the data is received, it takes just a time equal to GOP duration to start displaying a new sub-stream.
Every sub-stream in ABR may have its own codec. With this feature you can combine high resolution sub-stream with H.265/HEVC and other sub-streams having H.264/AVC or use other codecs like VP8/VP9.

SLDP and ABR setup

General process of SLDP playback setup in Nimble Streamer doesn't differ from RTMP playback setup. This article shows step-by-step procedure which is very simple with WMSPanel control panel web UI.

ABR setup in Nimble Streamer is described at this article and it's also straight-forward. It includes input streams processing and output setup. Notice the graceful adaptive bitrate stream approach used in Nimble.

If you don't have various renditions from and need to create them from your original stream, you may use our Live Transcoder, and try wildcard setup in particular to simplify this process. Also check this Transcoder video showing the setup process.

If you use Transcoder, you should also perform key frame alignment for all single-bitrate streams. Sometimes when you switch between different stream's renditions you can see a some short glitch. This happens because a player need a new GOP to start the playback. Different streams may have their key frames aligned differently, so each new GOP will start from different point. To avoid that, you need to perform key frame alignment. Use this article to set key frame alignment in your transcoding scenarios.

SLDP Player usage

Having SLDP stream, you can now use our players to provide the playback to your users.

You may use 3 options:

  • HTML5 player provides playback in any browser which supports MSE. This includes basically any Windows, Linux and MacOS platform. Even Android browsers will allow you to load and play SLDP via HTML5 SLDP player.
  • Android native app provides playback in case you don't want to use web playback on user devices.
  • iOS native app is needed in case you need to play SLDP on Apple mobile devices. You can use it as a fallback for browser player.

All players are free of charge. They also have respective SDKs so you could customize them for your user experience.

SLDP HTML5 player setup also may optional parameters to tune the ABR playback.

If you'd like to set initial resolution which you want your uses to see by default when the player is loaded, use this setting:
initial_resolution = <width>x<height>
If you use key frame alignment as described above, you should use this parameter to obtain smooth rendition switching:
key_frame_alignment = true
You may also use latency_tolerance parameter to tune the streaming latency as described in this article.

That's it. With steps described above you will have full-featured SLDP ABR playback on any platform you need.

Also, you can take a look at the SLDP frequent questions to improve your SLDP usage. And read Reliable Low Latency Delivery with SRT+SLDP post in Haivision blog describing a combination of both protocols for building reliable delivery networks.

Visit SLDP website and contact us in case of any questions regarding SLDP technology usage.

August 7, 2019

Using Certbot with Nimble Streamer

Certbot is a popular tool for working with Let's Encrypt certificates. Nimble Streamer has full support for SSL-protected streaming so let's see how you can use Certbot with Nimble Streamer for your convenience.

1. Set up Certbot

First go to Certbot website and scroll down to "My HTTP website is running" line. Choose "None of the above" option in Software field and then your OS in "System" field.

Let's use Ubuntu 18.04 for our example.

You'll be redirected to page with necessary instructions.

Follow steps 1 through 4 to install and setup Certbot.

2. Set up certificate

On step 5 - "Install your certificate" - you need to add use your new certificate in Nimble Streamer configuration.

Add these lines to your /etc/nimble/nimble.conf file:
ssl_port = 443
ssl_certificate = /etc/letsencrypt/live/
ssl_certificate_key = /etc/letsencrypt/live/
and then re-start Nimble Streamer with this command:
sudo service nimble restart
You can find more info about nimble.conf on this page.

If you need more complex setup scenario like multiple domains or encryption methods, you can follow this article to set up SSL certificate properly.

By this step, you'll have Nimble Streamer instance running with valid SSL certificate.

3. Set up certificate renewal

The last step will be to set up the automatic renewal of certificate. Certbot does this perfectly, however we'll need to make it call Nimble Streamer for reload the certificate. This can be done via Nimble Streamer native API.

First, set up management API as described on this page under "Starting point: enable API access" point.
Here's an example you can use:
management_listen_interfaces =
management_port = 8083
Then re-start Nimble Streamer instance:
sudo service nimble restart

Second step will be to run the renew command as described in "Test automatic renewal" section, with additional post-hook parameter like this:
sudo certbot renew --post-hook 'curl -X POST'
Once Certbot renews the certificate it will reload the SSL certificate by making proper API call.

That's it. If you have any questions or issues, feel free to contact us via helpdesk.

Related documentation

SSL setup for Nimble Streamer, Paywall feature set

July 31, 2019

Constant bitrate and mux rate in UDP streaming

Nimble Streamer has wide feature set for MPEG2TS streaming. This includes full UDP support to allow Nimble Streamer receive and send content via that protocol.

Streaming without bitrate setup

When you stream from Nimble Streamer via UDP, a variable bitrate is used for output by default. You can find all details of UDP streaming setup in this article.

However, in some cases of using DVB/ATSC and other hardware, a lot of ETR101290, CC and PCR errors appear on a regular basis making it hard to use it.

Take a look at this Wireshark session which logged an output of UDP stream.

You can see large spikes which cause problematic behavior on sensitive hardware.

Streaming with mux rate

The first step to mitigate this is to specify exact mux rate for outgoing stream to set the upper limit. To specify mux rate parameters, click on "Mux rate" checkbox in UDP settings as shown below.

Here you can define Mux rate field value with the bitrate you'd like to have. Notice that it should be 20% to 30% bigger than the maximum bandwidth of your original content. Other mux rate tuning fields like Mux delay and Max mux delay can be specified as well.

Now you can re-start your stream to see how it affected the output. First we looked at the stream using Wireshark with 1 second interval.

It looks much better, however if we select 100ms interval, the picture is much less smooth.

Even though an average bitrate is near the target value, you see the spikes which will still affect many types of hardware.

Streaming with constant bitrate

To keep the bitrate on the same level, Nimble Streamer allows setting constant bitrate (CBR). Nimble calculates the exact time interval between packets using MPEG-TS packet size and required bitrate, then sends those packets out strictly at designated time slots. With CBR technique, the packets are kept and processed via the CBR buffer.

CBR behavior is enabled by Max CBR buffer field. It defines the maximum total duration of packets in CBR buffer for further processing. If the incoming data overflows the Max CBR buffer, the stream will be reset.

When the stream has been started and the incoming data starts arriving, Nimble Streamer stores the packets into CBR buffer. Start CBR buffer parameter defines the duration of packets which Nimble collects before starting to send them out.
E.g. if you set this to 1000ms and start the stream, Nimble will keep getting data and putting packets into buffer, and after the total duration of packets in the buffer reaches 1000ms, Nimble will start sending the packets with calculated intervals.

As long as data keeps arriving, the packets will be placed in the buffer for further sending.

If the CBR buffer runs out of packets (due to some incoming stream problems), Nimble Streamer will then wait for incoming data to fill the CBR buffer for the duration set in Start CBR buffer before starting to send the data out again. So Start CBR buffer value is used in 2 cases - when the stream has just been started and when the stream has had some problems.

Notice that the bigger Start CBR buffer you set, the bigger the output latency you will have. If you set it to some low value or just keep it blank, then you may face some glitches in Nimble output, just because it will depend on your incoming stream's conditions.

The numbers may differ according to your input streams. If your source is an RTMP stream and your network conditions are good, you can use 1000ms Start CBR buffer and 10000ms in Max CBR buffer.

If you use HLS as an input, those numbers need to be larger as it's a chunk-based protocol. E.g. for a stream with standard 10-seconds chunks the start buffer needs to be 20000 and max buffer can be 60000.

With these settings, once we start the input RTMP stream, the 100ms chart in Wireshark looks like this.

Some rare spikes still present once in a while due to system network deviations but the line is generally flat on the target bitrate.

Notice that CBR works only when Nimble Streamer is installed on Linux or MacOS because Windows doesn't allow working with precise intervals required for this technique without using complex and risky methods.

PCR metrics

Overall, according to StreamGuru, when it comes to UDP streaming, Nimble Streamer has PCR accuracy of 100%. While hardware receivers accept up to 500ns PCR drift, Nimble Streamer produces PCR with 0ns drift. Also, PCR interval is <20 ms while 40ms is acceptable by most hardware.

If you have any questions about working with UDP streaming via Nimble Streamer, please contact us.

Related documentation

July 28, 2019

Handling session IP change in Nimble Streamer

Nimble Streamer uses sessions to track users' stats as it's important to see how the content is consumed. It's used in every end-user connection unless you use HTTP origin feature to remove the session identifier.

Every session is based on user IP to be able to distinct them from one another. Normally if a session starts with some IP, it keeps using that IP until the connection is closed. If the original connection IP changes, Nimble Streamer will close the connection because IP change most probably means that someone else uses your session ID which is not good from security standpoint. The viewers with closed connection will get response code 403.

However in some cases the IP change doesn't mean anything bad. For example, if your Android users use Lite mode (also known as Data Saver), Google will use its own proxy servers to accelerate the data usage. Also, your users may use other trusted proxies for their own legit purposes.

For cases like these you may use a few features of Nimble Streamer.

Disable IP check

First of all you may disable session IP check. This can be done using this parameter
restrict_session_ip = false
in nimble.conf. Please read configuration reference page for details on parameters' setup and usage.

Once you disable it, your streams' direct links may be used by several viewers so you should use this approach only in case your viewers use trusted proxy servers.

Tune hotlink protection

If you use hotlink protection from WMSAuth paywall feature set and your viewers use proxies as described above, they will get error 403 and you'll find "cannot find hash match" in Nimble logs. That will happen even if you disable session IP check.

So the next thing you should do after disabling restrict_session_ip, is to use different headers for obtaining end-user IP in WMSAuth code for your web page. This can be X_FORWARDED_FOR header or others, depending on your server and proxy software. Read this article regarding proxy usage to learn more about headers' usage.

Let us know if you experience any issues with the described features.

Related documentation

Nimble Streamer configuration referenceWMSAuth paywall, Using paywall with proxy servers,

July 25, 2019

Streaming Media European Readers' Choice Awards 2019

Streaming Media Europe magazine has started a vote for European Readers' Choice Awards 2019.
At the moment the voting is closed, if you are a voter, you receive an email asking them to to confirm the votes - please confirm it in order for it to be counted!

Please also have a couple of minutes to participate in Readers' Choice Awards 2019!

July 24, 2019

RTMP re-publishing control API in Nimble Streamer

Nimble Steamer has its own native status and control API which can be used for interacting directly with server instance rather than using WMSPanel control API. This native API can be convenient in case some  action needs to be applied without any delay.

There's a wide RTMP feature set in Nimble Streamer which covers the vast majority of aspects for live streaming. Re-publishing use case if very popular for building streaming infrastructure with origins and edges so our customers have been asking us for native API methods to work with it.

Now you can use new methods to do he following:

  • Get list of re-publishing rules;
  • Get details of selected re-publishing rule;
  • Create new rule;
  • Delete existing rule;
  • Get status of all current re-publishing rules.
You can visit native API reference page to find all details about these methods.

Notice that re-publishing setting defined by "create" and "delete" API calls are not persistent and they are reset after Nimble Streamer re-load. If you'd like to keep them, you should use WMSPanel control API.

Related documentation

July 3, 2019

Passing Icecast metadata in Nimble Live Transcoder

Nimble Streamer has an advanced audio streaming feature set. Live audio streaming covers transmuxing of Icecast pulled and published streams, audio transcoding in Nimble Live Transcoder and ads insertion via Nimble Advertizer.

Metadata is an important part of Icecast usage. We've previously added appending Icecast metadata to live streams and Icecast metadata passthrough tags support. However, by default Live Transcoder doesn't pass metadata through when transforming audio content.

Our long-term customers StreamGuys, who extensively use our audio streaming features, asked if we might add a passthrough of Icecast metadata while using Live Transcoder. Our clients' feedback has always driven our development so we keep adding elements which are helpful to entire audio streamers community.

We're glad to announce that we've improved Live Transcoder to allow setting up metadata passthrough for audio. This feature needs some additional setup so follow the instructions below if you'd like to use it.

1. Set up Nimble configuration

First, this feature needs to be explicitly enabled for the server.

Add this parameter into your nimble.conf file:
icecast_forward_metadata_through_encoder_enabled = true
This reference page describes how you can work with Nimble configuration in general.

2. Add new parameter in transcoding scenario

We assume you're already familiar with Live Transcoder setup and you already know how to create a transcoding scenario where you need the metadata to pass. You can take a look at Transcoder website and a set of videos to refresh your knowledge.

To make the output stream to have a metadata from some incoming stream, you need to add icecast_metadata_source custom parameter to audio encoder settings.

As the encoder element of transcoder scenario allows receiving content and other data from any decoded stream, with additional filtering on top, you need to specify which stream is used as a source for your metadata.

Specifying exact name

Take a look at an example of encoder setting.

Here you see original content blue decoding element with application name "live" and stream name "origin". For encoder output element you see new app and stream names and also additional "icecast_metadata_source" parameter with "live/origin" value which indicates the exact original stream.

Specifying wildcard stream name

Live Transcoder allows using wildcard stream name for the convenience of setup. Take a look at this example.

Here you can see decoder element has "live" app name and "*" as a stream name. This means decoder has no stream name specified which allows using whatever incoming stream name you have. If you look at encoder settings, you can see "{STREAM}_output" as a stream name, where {STREAM} is a placeholder for any input stream. So in the example above if your input is "live/radio", your output will be "live_radio/radio_output".

This wildcard approach is also used for "icecast_metadata_source" parameter. In our example you see "live/{STREAM}" as a value. This means that if your input source is "live/radio", then "live/radio" will be used as a source of metadata.

You can also simplify the setup process further. If your decoder app name and encoder app name are the same, you can skip the app name in parameter value and keep only {STREAM} as shown below.

In this case the application name is "inherited" from the encoder application ("live" in this case) which is equal to source decoder app name.

3. Apply new setting

Metadata passthrough cannot be applied on-the-fly to a transcoding scenario unlike other parameters. In order to make it work you need to save your scenario and then perform either of these steps:

  • Re-start the input stream
  • Or pause/resume the scenario. Go to scenarios list, click Pause icon, wait for the pause to sync with the transcoder, click on resume icon to start it again.

Once you do any of those 2 options, the metadata will become available in your output.

Let us know if you have any suggestions or questions about our Icecast feature set, we're opened for discussions.

Related documentation