Universal Media Server | Forum

Hi, I'm in trouble to understand some basic essential settings, so, the questions are:

1 - Is the Maximum bandwidth in Mb/s responsible for limiting the stream transference through wifi ?
So, if I have an internet connection of 15 Mbps for download and 10 Mbps for upload and a modem of 54 Mbps to wireless connection and I'm using all the internet (25 Mbps), Can I insert a value of 29 Mbps (54-25=29) to it without having delays ?

2 - Is the MaxVideoBitrateMbps, found in Renderer settings (.conf), responsible for limiting the Bitrate (Mb/s) showed at the bottom of Status section ? Is it overwrites what is in Transcoding quality (UMS setting) ?

3 - Correct me if I'm wrong: UMS take the video, transcode it at the rate defined in MaxVideoBitrateMbps, keep it in a circular buffer sized by Maximum transcode buffer size in MB (Is this buffer in some cache folder or RAM memory ?) and send the file in the buffer at the rate defined by Maximum bandwidth in Mb/s.

4 - My internet connection is like described in the first question and I'm using MiraScreen as renderer with ChromeCast.conf as reference. I just set it to:

TranscodeVideo = MPEGTS-H264-AC3
TranscodeAudio = MP3
MaxVideoBitrateMbps = 8

And UMS to :

Maximum bandwidth in Mb/s = 10
Maximum transcode buffer size in MB = 400
Transcoding Quality = Lossless quality (in both)

I've watched two movies and after 40-50 min in both, the buffering bar appeared for 2-3 minutes, after that it disappeared and the movie played as well as before. I don't know what happens if the buffer was filled up and emptied or something else .... Can I fix it increasing the Maximum transcode buffer size ?

5 - How can I create playlists to be played in some renderer ? I tried the + button at the renderer player but it didn't play the next file.

1) UMS can't limit the bandwith for non-transcoded files, they are simply transferred as requested by the renderer. If the bandwidth is higher than the specified value, the media will be transcoded instead. The bandwidth limitation limits the quality of the transcoding. This is the only thing possible to limit, as the playback speed is fixed (it has to play at 1x). UMS doesn't do any bandwidth throttling on the network level and won't keep within the defined limit if the network allows more bandwidth in short bursts, it simply tries to make sure that the average bandwidth is within the limit so that the playback will be continous if the network is limited to this bandwidth.

Your calculation is wrong. While most wired connections are full duplex (where send and receive is independent and can be done simultaneously), Wifi is half duplex and can only transfer one direction at a time. That means a theoretical 54 Mbps (which is far from a real value) in either direction. When transferring both ways some sort of algorithm has to alternate the transfer direction. I don't know the details of how this works, but I'm pretty sure that this starting and stopping also has its cost (the two ends also has to communicate their intentions and cooperate) so that the will be some significant overhead. A simple addition of the up- and download speeds is probably very optimistic.

The more important part of this is that the theoretical maximums for wireless transfers are usually very far from any real-life achievable speeds. There are many factors that impact the actual speed, anything from signal strength (distance + obstacles) and interference to router/NIC implementations. A rule of thumb is that the real bandwidth is usually somewhere around half of the theoretical. That means that your Wifi probably won't be able to handle full utilization of your internet line alone, and there certainly won't be anything left for UMS.

That said, it all depends on how you use your network. It isn't easy to find ways to saturate a 15/10 Mbps connection without running some sort of seedbox or other "service", so I don't know if considering full utilization is really relevant. UMS won't use more bandwidth than the content requires either, the limit is only an upper limit. You might be fine with this setup in practice, but if you really want to be able to fully utilize both UMS and your internet connection I'd simply say: Ditch your Wifi and use 1 Gbps full duplex network where you won't come anywhere close to the network's limitation. A 802.11ac solution might be a solution as well, although wireless is never as fast as the numbers suggest.

2) The renderer setting does the same as the "general" setting, but applies to that renderer only. The actual limit used will be the smallest of the two. The reason for this is that many renderers have bandwidth limitations on what they can process and/or their network implementation can handle. That limitation is fixed for a given renderer and is independent of the local network. Think of the "general" setting as the one describing your network's limitation and the renderer setting the one describing that device's limitation.

3) Partly. UMS will tell the transcoding engine to keep the output within the defined maximum bitrate and buffer this is a circular buffer in RAM. The output from the buffer however is not limited and can be empties as fast as the renderer/network desire or can handle. The renderer generally won't buffer very much itself, so the requests will normally happen in bursts that averages to the playback speed.

4) That sounds like a bug with the GUI or the calculation rather than something that really happened, but a trace log would be needed to see what really happened.

5) I have never looked into or used the playlist functionality so I don't know how or how well it works, but the way I thought that it worked was that you could create playlists using other software (or manually for that sake) and share those files with UMS along with the media contained in the playlist, and the playlist would present as a "virtual folder" where the media is presented and played in the order of the playlist.

Thank you very much, I was just putting random values to those parameters without the true thinking.
- Network limit: 10 Mbps
- MaxVideoBitRate: 15 Mbps
- Transcoding buffer: 400 MB

These settings seem to work fine in my network.

About the playlists I solve this downloading Samsung All Share, connecting with UMS, making the playlist with the files from the shared folder from UMS and choosing to play in another device (I selected my renderer Mirascreen). The nice part is that the files are played using my renderer settings from UMS, which is also responsible for transcoding them, so, now I can see the subtitles using Samsung All Share.