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m3u extended playlist comments useful?
24-05-2016, 14:24
Post: #1
m3u extended playlist comments useful?
I have been trying to figure out a system for constructing playlists, and I realized that the m3u format is simpler than I thought: all I actually need is just a list of files and the .m3u extension.

So I'm wondering whether the extended playlist comments, the #EXTINF data, serve any purpose. Does MinimServer benefit from these? (Do other players?)

In my collection I have flac files (that MinimServer serves) and I have a second copy of my music in mp3 for putting on devices where space is a consideration. I understand that mp3 files aren't the same length as the original (there is some sort of padding) so that means I if the #EXTINF information is present, I couldn't just convert a flac based m3u file to an mp3 based one with a script that changed occurrences of flac->mp3. Am I right about that?
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24-05-2016, 15:48
Post: #2
RE: m3u extended playlist comments useful?
The duration in the #EXTINF line is the track duration in seconds. Changing the file format doesn't change the track duration.

If the playlist entry is a file in the MinimServer library, the duration and title are taken from the referenced file, not from the #EXTINF line.

If the playlist entry is another playlist, the title is taken from the #EXTINF line if present.

If the playlist entry is a network URL, the duration and title are taken from the #EXTINF line if present. The [] prefix in the #EXTINF title (if present) is used to provide a stream ID for MinimStreamer and other information about the stream.
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24-05-2016, 16:04
Post: #3
RE: m3u extended playlist comments useful?
(24-05-2016 15:48)simoncn Wrote:  The duration in the #EXTINF line is the track duration in seconds. Changing the file format doesn't change the track duration.

It seems like it shouldn't, but I have read that encoders and/or decoders add some silence at both ends, something having to do with frame lengths of the mp3 encoding algorithm. I encountered this as an explanation for why gapless playback may be difficult with mp3. I assume in the end these length values are just used to tell the user how long the play list will last, so errors that are small don't matter.

Quote:If the playlist entry is a file in the MinimServer library, the duration and title are taken from the referenced file, not from the #EXTINF line.

If the playlist entry is another playlist, the title is taken from the #EXTINF line if present.

If the playlist entry is a network URL, the duration and title are taken from the #EXTINF line if present. The [] prefix in the #EXTINF title (if present) is used to provide a stream ID for MinimStreamer and other information about the stream.

Thanks for this detail about how the information is used. It sounds like from MinimServer's point of view, maintaining #EXTINF lines for a playlist of local files is just wasted effort. It also crossed my mind that if I were to change a title or artist for some reason then those #EXTINF lines would need to be updated, another complication of the extended info. I did start wondering about how play lists are titled when browsing and how they show up in the interface---presumably based on file name since there is no metadata to give a name or any organization. Or is it recommended to create one master playlist that lists all the other playlists and use the #EXTINF to give titles for them?
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24-05-2016, 17:37
Post: #4
RE: m3u extended playlist comments useful?
(24-05-2016 16:04)adrian Wrote:  It seems like it shouldn't, but I have read that encoders and/or decoders add some silence at both ends, something having to do with frame lengths of the mp3 encoding algorithm. I encountered this as an explanation for why gapless playback may be difficult with mp3. I assume in the end these length values are just used to tell the user how long the play list will last, so errors that are small don't matter.

Any padding needed to fill an MP3 frame would be so short that it's extremely unlikely to affect the duration in seconds. As you say, this value is purely informative.

Quote: I did start wondering about how play lists are titled when browsing and how they show up in the interface---presumably based on file name since there is no metadata to give a name or any organization. Or is it recommended to create one master playlist that lists all the other playlists and use the #EXTINF to give titles for them?

When viewing playlists from the # playlists container, the file name is used. If the playlist is referenced from another playlist, the reference will have the name from #EXTINF if present. It is your choice whether the extra level of indirection when browsing is worth the benefit of having a friendlier name.
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