Some ogg do not play

[yonkiman]

OK, I'm having similar (though much more bizarre) ogg trouble, and I'm not afraid to show you my files.  They are here:  http://www.oneawkwardmoment.com/sounds/ogg_issues.zip

Here's the background.  I recently reformatted my rockbox drive and resynced everything.  Most of the files in my library are FLAC, but MediaCenter converts them to ogg on the fly when I sync to my rockbox.  So all of these files were converted to ogg at the same time by the same software with the same cover art image.  Most of the ~200 albums I synced work fine.  But Queen's News of the World is acting very strange...

Here are the tracks on the playlist (I don't like tracks 3 and 6 so I don't sync them to my Rockbox):

1. We Will Rock You
2. We Are the Champions
4. All Dead, All Dead
5. Spread Your Wings
7. Get Down, Make Love
8. Sleeping on the Sidewalk
9. Who Needs You
10. It's Late
11. My Melancholy Blues

After I sync, all 9 tracks appear in the correct directory on my Rockbox drive.  I can play any of them off of the Rockbox hard drive using a Windows media player and they sound fine - so there doesn't seem to be any file corruption.

But after I do a Database Initialize or Update, these are the tracks that show up in the database:
1. We Will Rock You
4. All Dead, All Dead
5. Spread Your Wings
7. Get Down, Make Love
9. Who Needs You
10. It's Late
11. My Melancholy Blues

Tracks 2 and 8 are missing.  And when I tell it to play starting from track 1, it skips through all 7 tracks sequentially, not able to play any of them.  That's when I try to play the songs from the Database view.

When I try to select them from Rockbox File view, it displays all 9 files in the directory (as you would expect), but when I have it start playing the files from track 1, it skips 1, PLAYS 2, skips 4, 5, and 7, PLAYS 8, and skips 9, 10, and 11.

So it seems it will only play the files it can't index! 

This makes no sense to me.

I've got a 60GB ipod video.   I'm running Rockbox r30224-110730.  All the files were ripped and converted by the same program at the same time, and they all have the same cover art.  The zip file linked to at the start of this posting contains tracks 1 and 2:  Track 1 indexes but won't play, and 2 doesn't get indexed but will play.

Any ideas appreciated - I'm baffled!

[OxonOwl]

Sounds complicated and confusing.

As with my solution I would try removing all tags and see if they play. Then try adding the tags again.

In my case I obviously had something funny in the tags

[saratoga]

How big is the coverage?

[yonkiman]

How big is the coverage?

I deleted the cover in my FLACS, and the delta was 728kB, so that would be the approximate cover size.  Does rockbox have an upper limit?  Also, track 1 and track two both had the exact same size cover - so not sure why the behave differently.

Anyway resyncing with cover-less versions to see if it's cover-related or not.

Thanks for the support OxonOwl and saratoga.

[saratoga]

How big is the coverage?

I deleted the cover in my FLACS, and the delta was 728kB, so that would be the approximate cover size.  Does rockbox have an upper limit? 

ha.  You have 1MB for the entire vorbis decoder.  Using 75% of that on coverart is not going to work.

Ogg isn't supposed to have embedded binary data at all, so the parser assumes that any metadata is small and then fails if its not.  I've put some effort into trying to fix this design choice, but its nontrivial given how Ogg works.    You probably shouldn't be putting cover art into Vorbis if you can avoid it.  If you can't, use small files.  It will decrease the risk that you'll break things. 

[yonkiman]

ha.  You have 1MB for the entire vorbis decoder.  Using 75% of that on coverart is not going to work.

You're totally right!  I deleted all the album art, shaved 486MB off the space my oggs take up on my ipod, and the album loads and is indexed perfectly. 

So thanks!

But I'm still curious why this matters.  The decoder plays the file sequentially - why doesn't it ignore the album art - why does it get loaded into the 1MB it has to play with?  The album art image is always the same low res on the Rockbox, so I don't see why that should be a problem.

I'm sure there's a good reason, I'm just curious what it is!

Again, though - thanks for the support!

[Lear]

The answer is fairly technical, but an Ogg file is split into a number of chunks of data called packets, and the Ogg reader part of the decoder always loads a full packet into memory. Vorbis puts all comments into one packet. For short, descriptive text, this works fine, but when you put a big image there it doesn't work too well. Getting the Ogg layer to skip a particular packet is the tricky part (I've looked a bit into it as well).

[saratoga]

The decoder plays the file sequentially - why doesn't it ignore the album art - why does it get loaded into the 1MB it has to play with?

Because Ogg tags are only supposed to be a few KB, so the decoder assumes it not necessary to load them sequentially.