[Matroska-devel] Comments on the "Audio Tags Example, Simple CD layout" at matroska.org

Steve Lhomme steve.lhomme at free.fr
Thu Sep 30 15:08:01 CEST 2004


Vegard Pettersen a écrit :

> I'm working my way through the chapters and tag examples at matroska.org, and 
> I have a few viewpoints that may or may not be overly critical.
> I couldn't find a mailing list for the website, so I hope using this list is 
> okay.

Yes, it's find. Every "technical" discussion can be discussed here.

> Referring to 
> http://www.matroska.org/technical/specs/tagging/example-audio.html#intro, I 
> find this example confusing and possibly wrong.
> The statement: "Tracks 01 to 04 are linked together and are actually making 
> just one "virtual" track to the listener.", I find unclear and inaccurate.

In that case, I know *for sure* that those tracks are meant to be one. I 
know the guys who created this track and heard it in the studio before 
it was released. It used to be one track (called Baby Wants To Bleep) 
but became 4 because of contract issues with Virgin.

> Just because there are no pregaps between some tracks does not change the fact 
> that each track can be sought to. The meaning of "a virtual track" appears to 
> me to only make sense if you ignore the concept of indices in a track. When a 
> track has indices above INDEX 01, not all CD audio players can seek to such a 
> seekpoint, very few people bother doing that, and I don't know of _any_ 
> CD-ROM players that seek to such seekpoints. Therefore, making a track with 
> indices over INDEX 01 would have the effect of making "one virtual track for 
> the listener", whilst a number of tracks with pregaps of zero seconds is 
> still a number of individual, seekable tracks.

See above :)

IIRC the contract with Virgin stated that they had to release an album. 
But they didn't have one. So they cut this track instead and in the end 
it's called a mini-album and everyone is happy. Remember that record 
companies are evil and they will not you use nice technologies (like CD 
index) if it's not what the contract says...

> Furthermore, I do not find the reason for grouping the four first tracks into 
> a "00:00 - 12:28 : Baby Wants To Bleep/Rock" based on the CD-information 
> available at amazon.com 
> ( http://www.amazon.com/exec/obidos/tg/detail/-/B000042VQM/qid=1096218210/sr=8-3/ref=sr_8_xs_ap_i3_xgl15/104-7128524-5572701?v=glance&s=music&n=507846#product-details ), 
> freedb.org 
> ( http://www.freedb.org/freedb_search_fmt.php?cat=newage&id=5b0a6e09 ),
> or at discogs.com ( http://www.discogs.com/release/8788 ).
> I see this grouping as an artificial construct based on length of pregaps, and 
> it is confusing.

Every system should be flexible enough to care with human flows ;)

> Referring to 
> http://www.matroska.org/technical/specs/tagging/example-audio.html#whole, 
> this is also slightly confusing.
> "In this case the file contains one continuous audio track of 44:28. Chapters 
> are used to virtually split the content in many parts, ie the CD tracks. A 
> basic ripping application would rip the CD tracks as follows"
> What exactly is the combined meaning of "one continous audio track" and "the 
> CD tracks"? Is the cd one continous track, like the early release of "Mike 
> Oldfield_Amarok" ( http://www.freedb.org/freedb_search_fmt.php?cat=misc&id=020e0601 ), 
> or is the meaning that there is one track with many indices which for some 
> reason is split into tracks?

Yes. All the audio content is glued together and put in one Matroska track.

> Seeing that "mkvextract cuesheet foo.mka" and mkvmerge now both handle indices 
> over INDEX 01 (mosu, can I commit this to the svn for mkvtoolnix or should I 
> just send the modified files to you in mail?), maybe this example should be 
> modified. I think it might be less vague if there was a CUE-file included in 
> the example as well.

I could add the CUE file, if I know how to create one ;)

> Referring to: 
> http://www.matroska.org/technical/specs/tagging/example-audio.html#meaningful, 
> the meaning of "meaningfull" again escapes me... with a cuesheet, it is 
> possible to burn a wav having pregaps less than two seconds, so grouping the 
> "no pause between"-tracks into is completely artificial. 
> Sure, I understand the argument that "you can do it if you want to", I just 
> don't see the point. Is it indended to make gapless playback easier or 
> something? If so, I don't see why that should be the responsibility of a 
> container format, that's in my view a player / demuxer's responsibility.

See above for the reasons.

Now, it's a container problem, because tags are a container thing... I'd 
definitely have that track I heard in the studio as 1 track instead of 
4. For example it sucks in a player when you have random on, and you 
only get a 4th of a track for stupid reasons (only iTunes allow to do 
that for the moment). But the nice thing in Matroska is that you don't 
lose the information that this track is actually cut in 4 pieces on the CD.

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