Spooler: Difference between revisions

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If you enable the Spooler in the Advanced Preferences, you get these benefits:
The Spooler is an integral part of kJams, and provides these benefits:


# you enable background ripping: rips will happen in the background, not interfering with your use of kJams while it does it's work
# Play direct from CD without manually ripping first
# you enable background encoding: encoding too happens in the background
# background ripping: rips will happen in the background, not interfering with your use of kJams while it does it's work
# ripping will be at the full speed of your drive.  That is, it won't be slowed down by the encoding process.  With the spooler, ripping happens on it's own thread, which is *just* a tight loop reading from the CD and writing to a chache file on your hard drive.  In writing to this cache file, there's no audio encoding, no subchannel descrambling or error correcting, so it writes as fast as possible, making the rip go as fast as possible.
# background encoding: encoding too happens in the background
# you enable the cache: The cache stores uncompressed audio and video.  If you play a song off the CD, and then decide to import it, it doesn't have to rip because it's already in the cache.  Likewise, the next time you play it, it does not have to read it from the CD.  Soon, if the file was zipped, it will also go into the cache, so next time you play it it will not have to be unzipped.
# ripping will be at the full speed of your drive.  That is, it won't be slowed down by the encoding process.  With the spooler, ripping happens on it's own thread, which is *just* a tight loop reading from the CD, and writes into memory (a deque for those who want to know).  For this "read loop", there's no audio encoding, no subchannel descrambling or error correcting, so it reads as fast as possible, making the rip itself go as fast as possible. (there is a second, separate thread that reads from the deque and writes mp3 and cdg)
# you enable perfectly sample accurate playback of songs ripped from CD (soon, the same will apply to MP3's and Zip files, even ones encoded with variable bit rate)
# you enable the cache: The cache stores uncompressed audio and video.  If you play a song off the CD, and then decide to import it, it doesn't have to rip because it's already in the cache.  Likewise, the next time you play it, it does not have to read it from the CD.  If the file was just in your library, it is unpacked (decoded from MP3 or whatever) into uncompressed.  If the file was zipped, it will also go into the cache, so next time you play it it will not have to be unzipped or unpacked.
# you enable full QuickTime playback: This won't mean much to you yet, but now that QuickTime is handling the audio stream rather than CoreAudio, I get a dozen more file formats for free.  Coming soon: OGG Vorbis Encoding and Playback.  Eventually you'll see movie playback, including KAR files.
# you enable perfectly sample accurate playback or audio with lock-on sync to video, when you [[Screen_Shots#LCD_Panel|scrub the play head]], even for [http://developer.apple.com/documentation/QuickTime/QT6WhatsNew/Chap1/chapter_1_section_37.html VBR compressed audio].
 
Future benefits:
# Playback of all QuickTime formats: Now that QuickTime is handling the audio stream rather than CoreAudio, I get a dozen more file formats for free.  Coming soon: OGG Vorbis Encoding and Playback.  Eventually you'll see movie playback, including KAR files.
# Cue multiple songs with crossfade
# Cue a song to it's first non-silent sample, so when you un-pause the music starts instantly


You will want to have the Tasks window showing, that way you can see all the spools that are running.
You will want to have the Tasks window showing, that way you can see all the spools that are running.


You may have already seen the benefit of playing directly from CD.  You see how fast the rip goes?  That's how fast it goes when encoding too.
You should take care to manage the spooler's audio cache, see [[Preferences#Audio|Preferences]].
 
Q) Why is it turned off by default?<br>
A) Because it's a brand new feature and I want to be sure that it doesn't crash on casual users.  If you're excited to see the potential, and don't mind too much if you run into a bug, you should turn it on.
 
Keep in mind there's no cache management right now, so it can grow arbitrarily large.  If you find yourself low on disk space, you may want to delete your cache.  it's located in /Library/Caches/kJams/.  Note that's the root of your drive, NOT under your user.  (ie: users will share the kJams Cache).  You can throw out that folder any time kJams is not playing or ripping.  Soon there will be a pref panel for cache management.
 
Please turn it on, and use it, and report bugs.  I need to get all the bugs out before I feel ready to turn it on by default.

Revision as of 23:46, 3 January 2006

The Spooler is an integral part of kJams, and provides these benefits:

  1. Play direct from CD without manually ripping first
  2. background ripping: rips will happen in the background, not interfering with your use of kJams while it does it's work
  3. background encoding: encoding too happens in the background
  4. ripping will be at the full speed of your drive. That is, it won't be slowed down by the encoding process. With the spooler, ripping happens on it's own thread, which is *just* a tight loop reading from the CD, and writes into memory (a deque for those who want to know). For this "read loop", there's no audio encoding, no subchannel descrambling or error correcting, so it reads as fast as possible, making the rip itself go as fast as possible. (there is a second, separate thread that reads from the deque and writes mp3 and cdg)
  5. you enable the cache: The cache stores uncompressed audio and video. If you play a song off the CD, and then decide to import it, it doesn't have to rip because it's already in the cache. Likewise, the next time you play it, it does not have to read it from the CD. If the file was just in your library, it is unpacked (decoded from MP3 or whatever) into uncompressed. If the file was zipped, it will also go into the cache, so next time you play it it will not have to be unzipped or unpacked.
  6. you enable perfectly sample accurate playback or audio with lock-on sync to video, when you scrub the play head, even for VBR compressed audio.

Future benefits:

  1. Playback of all QuickTime formats: Now that QuickTime is handling the audio stream rather than CoreAudio, I get a dozen more file formats for free. Coming soon: OGG Vorbis Encoding and Playback. Eventually you'll see movie playback, including KAR files.
  2. Cue multiple songs with crossfade
  3. Cue a song to it's first non-silent sample, so when you un-pause the music starts instantly

You will want to have the Tasks window showing, that way you can see all the spools that are running.

You should take care to manage the spooler's audio cache, see Preferences.

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