Streamit Lisa Compact, Руководство пользователя

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Lisa Compact 25
6.4 Mixed source playlist
The concept of single track playlist allows for changes to the music and commercial program 'on the fly'.
However, it does not have the bandwidth efficiency of Store-and-Forward. Each time a track is required
for playback, that track is downloaded and played (while being downloaded). Store-and-Forward on the
other hand is efficient in bandwidth usage, but does not have the flexibility to change the music and
commercial program or even add/use new content on the fly.
The 'mixed source playlist' makes it possible to use the content on the card while the music and
commercial program is determined on the server and can be updated as required. This means that an
Internet connection is still required, but very little data is being communicated.
It is also possible to use new content in the music and commercial program by making that available
online and pointing to it in the playlist. Hence the name: mixed source playlist. However, this content will
be downloaded each time it is played. On the one hand this means that the content is always fresh and
up to date, but also that more data is sent over the internet connection compared to using tracks that are
stored on the SD card.
Consider the following scenario: Generally the music is preplanned days ahead and tracks repeat
regularly in the program, while commercials are planned and updated even during the day. For such a
situation, the music can be downloaded to the card, to save bandwidth (also on the server-side). On the
other hand, the commercials are served 'live' online, so they can be updated when needed. The
single
track playlist method is used to make the Lisa play the music tracks from the SD card and the
commercials from the server.
For example, the first playlist may point to a music track on the card:
[playlist]
File1=PHAT0:/music.mp3
Title1=this is a music track
Length1=180
NumberOfEntries=1
Version=2
and the second playlist, downloaded after the first playlist is finished, points to a commercial (or track)
that is available online:
[playlist]
File1=http://myServer/audio/myAudioFile3.mp3
Title1=Online audio track
Length1=180
NumberOfEntries=1
Version=2
Note that the mixed source playlist method is described in combination with single track playlists, but
works also with playlists that are longer. If the playlist for example contains entries for 5 music tracks, all
5 tracks will be played before the Lisa makes a request for a playlist again.
Handling error conditions for mixed source playlists
The option to use tracks from the card in online playlists introduces a number of new error conditions.
Because the mixed source playlist method is a cooperation between server and Lisa, some of these
error conditions are best addressed on the server. For these error conditions, the following applies:
·
The Lisa will request a new playlist from the server
·
The error condition will be included in the header of the request that is sent to the server