Re: combine two existing large files

From: LEE Sau Dan (danlee_at_informatik.uni-freiburg.de)
Date: 10/04/04 

Date: 04 Oct 2004 23:09:31 +0200

>>>>> "Gary" == Gary Hu <garyhu@avis.idv.tw> writes:

>> In what way do you "combine those two files"? Concatenate one
>> to the end of the other or what?

    Gary> Yes, that's my hope.

I'm hope that's not. In that way, your video and audio streams will
be on very different parts of the disk. The playback may be not
smooth, because the disk head has to seek to here and there and here
and there for every small fragment of concurrent video/audio data.
Even if it is fast enough (e.g. on harddisk rather than on CDROM),
it'll not be a good idea for the health of your harddisk.

Normally, the video and audio streams are interleaved in the final
video+audio format, so that playback is possible by scanning the file
sequentially (with suitable buffer sizes to store the video/audio
fragments to be played shortly). I can't see how modifying the
sector/block tables of the filesystem would gain you that much
efficiency here. Moreover, such an approach would require the atomic
unit of the "shuffling" be in disk blocks, not bytes. Is that really
what you (not really you, but the ones consuming your resulting files)
could tolerate? 

-- 
Lee Sau Dan                     +Z05biGVm-                          ~{@nJX6X~}
E-mail: danlee@informatik.uni-freiburg.de
Home page: http://www.informatik.uni-freiburg.de/~danlee

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