Page 1 of 1

Adaptive bitrate question

PostPosted: Sat Aug 26, 2017 7:17 pm
by venom51
I haven't logged into the forums for a while because my DVBLink 4.1/HDPVR solution to this point has worked very well. I recently however have kicked DirecTV and thus AT&T out of my house again. Since I work for an IPTV middleware provider I have access to content via IP. I have the DVBlink for IPTV solution currently working and pulling streams but I'd like to know if the server side mechanism is Adaptive Bit Rate aware when pulling streams or can be configured to be so. In our case the internet facing product we offer will put out frame aligned streams at multiple bit rates. In this case a low of 1.5mbps, med at 3.5mbps and a high at 7.5mbps.

The M3u configuration page doesn't mention anything about Adaptive Bit Rate so my current assumption is that it is not aware.

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 11:49 am
by the_man
If i understand you correctly, then it is possible to get a playlist of channels for dvblink. But you will need to create an own m3u list with direct links to channels with required bitrate.
For instance:
you do have a list like:
#EXTM3U
#EXTINF:0,1 - myChannel 1
http://<link to channel 1>
#EXTINF:0,2 - myChannel 2
http://<link to channel 2>
...


Then you need to open:
http://<link to channel 1>
In browser and you will get a list of links to this channels with different bitrates

Then just create a new file in editor:
like a "myPlaylist.m3u"
and fill this file with links for each channel with appropriate bitrate
Something like this:
#EXTM3U
#EXTINF:0,1 - myChannel 1
http://<link to channel 1 with 3.5mbps >
...

Then store this m3u list at the DVBLink/Share/Playlists/
Create a new IPTVSource and select this link under available.
Continue configuring...

http://dvblogic.com/wiki/index.php/DVBL ... ion_manual

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 12:06 pm
by Montoya
What Venom describes is the ability of the DVBLink IPTV server to recognize the available bandwidth of the client, so that the server decides at which bitrate, the selected channel is send to the client.

For example, my DVB-C provider has a web page and app for watching TV from the browser or app. If a client starts up a channel, the server detects the client bandwidth and sends a matching bitrate stream to the client. The client first sees a low quality stream and when the client has sufficient bandwidth, the server changes that stream to higher bitrate and resolution that the client can handle.

This is a rewrite for the DVBLink IPTV server package as far as I can see it, because the IPTV server has to know which <physical_channel> it must select for the client for the <logical_channel>.

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 3:43 pm
by venom51
We always request the lowest bitrate first to facilitate quick channel change times.

We deliver a master list for the channel that looks like the following.

#EXTM3U
#EXT-X-VERSION:3
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=1500000
1757/1757low/chunklist.m3u8?bcod=45024ec5-bc19-302e-a286-************
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=3500000
1757/1757med/chunklist.m3u8?bcod=45024ec5-bc19-302e-a286-************
#EXT-X-STREAM-INF:PROGRAM-ID=1,BANDWIDTH=7500000
1757/1757high/chunklist.m3u8?bcod=45024ec5-bc19-302e-a286-************

Our app then looks at the time it takes to download the last chunklist and makes the decision which bitrate to request next.

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 3:45 pm
by Oberon
For HLS streams with adaptive bitrate the highest available bitrate is taken automatically.

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 8:06 pm
by venom51
But DVBLink for IPTV will not try to grab a lower bitrate stream if the bandwidth to carry the highest bitrate stream is unavailable correct? That's that behavior I saw anyway.

Re: Adaptive bitrate question

PostPosted: Mon Aug 28, 2017 8:53 pm
by Oberon
venom51 wrote:But DVBLink for IPTV will not try to grab a lower bitrate stream if the bandwidth to carry the highest bitrate stream is unavailable correct? That's that behavior I saw anyway.

Correct.

Re: Adaptive bitrate question

PostPosted: Tue Aug 29, 2017 12:27 am
by venom51
It would be a nice feature to have. Can it go on the development feature request list or was this an architectural decision during development?