#28 Slow to start playing (d7 QT65 OS X iTunes 4.5)

[Chad]

Thanks for this component. Sorely needed and welcome!

Ogg files are very slow to start playing and cause the whole
computer to kind of pause when played uing QT and the Ogg Vorbis
component.

In iTunes, clicking and playing an Ogg file, the file doesn't start
playing for several seconds and the machine seems to pause as if
a great burden was laid on its shoulders. I am getting the files off
a samba share from a FreeBSD machine. Getting an MP3 file from
the same Samba share does not exhibit this problem. Local ogg
files seem to have the same problem.

800 mhz G4, 2GB RAM, OS X 10.3.3, d7 component, QT 6.5, iTunes
4.5

Thanks

[Steve Nicolai]

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I don't think there is anything I can do to make this better. iTunes loads
mp3's and AAC files using it's own code, and so can load a little bit at a
time. I don't know if it does the load in a separate thread or not, but it's
possible.

I suspect that iTunes loads files via QuickTime on the main thread (10.3
would support another thread, but not 10.2) You are seeing the network
latencies when you see the pause. I suspect if you were to look at the
CPU load during the pause, you'll see it's fairly low.

Please file a bug against iTunes to have it load QuickTime movies in
another thread on 10.3.

[Chad]

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ok, will do.

[Jesper L. Nielsen]

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Just a thought: The lag wouldn't have anything to do with looking for the
ID3 (or what ever it's called in OGG) at the ending of the file, an thus
have to seeks through the whole file? I haven't looked much at the code,
so bare with me..

[Anonymous]

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The problem is with either QuickTime or the OGG component. This delay
when opening files occurs in QuickTime player as well.

Poking around with Shark, I found that the delay is caused by
OggVImportFile being called. In other words, the component cannot play
from files directly. Here is the output from Shark:

# Report 1 - Session 1 - Time Profile of QuickTime Player
SharkProfileViewer
# Generated from the visible portion of the outline view
26.0% shandler (mach_kernel)
+ 13.6% ogg_page_checksum_set (OggVorbis.component)
| + 13.6% FindPage (OggVorbis.component)
| | + 13.6% ReadCompletion (OggVorbis.component)
| | | + 13.6% OggVImportIdle (OggVorbis.component)
| | | | + 13.6% OggVImportDataRef (OggVorbis.component)
| | | | | + 13.6% CallComponentFunctionCommon (CarbonCore)
| | | | | | + 13.6% OggVImportComponentDispatch (OggVorbis.component)
| | | | | | | + 13.6% CallComponent (CarbonCore)
| | | | | | | | + 13.6% MovieImportDataRef (QuickTime)
| | | | | | | | | + 13.6% OggVImportFile (OggVorbis.component)
| | | | | | | | | | + 13.6% CallComponentFunctionCommon (CarbonCore)
| | | | | | | | | | | + 13.6% OggVImportComponentDispatch
(OggVorbis.component)
| | | | | | | | | | | | + 13.6% CallComponent (CarbonCore)
| | | | | | | | | | | | | + 13.6% NewMovieFromDataRef (QuickTime)
| | | | | | | | | | | | | | - 13.6% 0x1d390 [4.0KB] (QuickTime Player)

If you open the OGG file in QT Player and save a small .mov file, the
.mov file will load and play without delay in both iTunes and Quicktime.

[Jesper L. Nielsen]

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Great debug work igni_ferroque, now that the problem has
been isolated, does anyone have a clue how to fix it?