Question: .
I am trying to understand how mpd file plays and i am referring to the following data set:
<http://www-itec.uni-klu.ac.at/ftp/datasets/mmsys12/Valkaama/MPDs/Valkaama_1s_act_isoffmain_DIS_23009_1_v_2_1c2_2011_08_30.mpd>

In mpd file format there is segment base consists of mp4 chunk and within it has chunk list with extension .m4s.I downloaded mpd file using :

<http://www-itec.uni-klu.ac.at/ftp/datasets/mmsys12/Valkaama/valkaama_1s/valkaama_1s_50kbit/valkaama_50kbit_dash.mp4>

and m4s chunk by following link:

<http://www-itec.uni-klu.ac.at/ftp/datasets/mmsys12/Valkaama/valkaama_1s/valkaama_1s_50kbit/valkaama_1s1.m4s>

I tried to play both mp4 and m4s in vlc player but not able to play any of these two so i want to ask which of the chunk links in the mpd file forma i can be able to play standalone in vlc player.

Please correct me if any of my observations is wrong:

Regards
Mayank

Answer: 
MPD file is just a index of streams with various formats in order to adapt to your bandwidth, to get more information follow the links of the other answers here.

It's possible to download all streams and merge them into a single file, you could achieve this by using youtube-dl:

```
youtube-dl http://URL/TO/manifest.mpd

```

You can get more information in <https://stackoverflow.com/a/39931712/1522342>.

Also, VLC 3.0.0+ can play that kind of file from a url, just open VLC, use the shortcut CTRL+N, paste the url and enjoy.
I dont think it is possible to play any of the files in a standalone player. The mp4 is the init segment which is required to decode the .m4s media segments. I dont think there is an option in the vlc player to map an init segment to multiple media segments. Nevertheless you can try a Dash player to play the manifest file. For instance [dash.js](https://github.com/Dash-Industry-Forum/dash.js)

> 
> **Initialization segment:** A sequence of bytes that contain all of the initialization information required to decode a sequence of media segments. This includes codec initialization data, Track ID mappings for multiplexed segments, and timestamp offsets (e.g. edit lists).
> 
> 
> **Media segment:** A sequence of bytes that contain packetized & timestamped media data for a portion of the media timeline. Media segments are always associated with the most recently appended initialization segment.
> 
> 
> 

Source: <http://www.w3.org/TR/media-source/#init-segment>