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Re: Script to conditionally find and compress files recursively

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Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> wrote:
> J Newman <jenniferkatenewman@gmail.com> writes:
> 
>> It's true that you cannot tell within the first 5 seconds what the
>> ultimate compression ratio will be, but it seems to me (from
>> compressing avi/mp4/mov files with lzma -9evv) that you can tell
>> within +/- 5% to a high degree of confidence, what the ultimate
>> compression ratio will be given the first 5 seconds.
> 
> Well then, I believe the solution was already posted. Grab 5% of your
> files with dd and see how it compresses. 

The solution that I see grabs the first 1MB, but it would make more
sense to sample eg. 1% of the file size in five places within the
file. 100MB file = 1MB sample, 100MB/5 = 20MB, so use dd to grab
one 1MB sample from the start of the file then four more at an
offset that increments by 20MB each time. Store these separately,
compress them separately, then average the compression ratio of all
the samples.

> I'm a little curious, what kind of space savings do you expect to get by
> doing this? And wouldn't it make more sense to re-encode for lower
> bitrate if space saving is your goal?

Maybe he's using lossless video compression? Otherwise yes it seems
like the wrong approach.

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Script to conditionally find and compress files recursively J Newman <jenniferkatenewman@gmail.com> - 2024-06-11 14:53 +0800
  Re: Script to conditionally find and compress files recursively D <nospam@example.net> - 2024-06-11 10:51 +0200
  Re: Script to conditionally find and compress files recursively Joe Beanfish <joebeanfish@nospam.duh> - 2024-06-11 14:58 +0000
  Re: Script to conditionally find and compress files recursively Grant Taylor <gtaylor@tnetconsulting.net> - 2024-06-11 22:21 -0500
    Re: Script to conditionally find and compress files recursively Richard Kettlewell <invalid@invalid.invalid> - 2024-06-12 08:17 +0100
      Re: Script to conditionally find and compress files recursively D <nospam@example.net> - 2024-06-12 10:13 +0200
        Re: Script to conditionally find and compress files recursively J Newman <jenniferkatenewman@gmail.com> - 2024-06-13 12:46 +0800
          Re: Script to conditionally find and compress files recursively D <nospam@example.net> - 2024-06-13 11:55 +0200
            Re: Script to conditionally find and compress files recursively Grant Taylor <gtaylor@tnetconsulting.net> - 2024-06-13 22:35 -0500
              Re: Script to conditionally find and compress files recursively D <nospam@example.net> - 2024-06-14 11:07 +0200
    Re: Script to conditionally find and compress files recursively J Newman <jenniferkatenewman@gmail.com> - 2024-06-13 12:43 +0800
      Re: Script to conditionally find and compress files recursively Anssi Saari <anssi.saari@usenet.mail.kapsi.fi> - 2024-06-13 10:13 +0300
        Re: Script to conditionally find and compress files recursively D <nospam@example.net> - 2024-06-13 11:55 +0200
        Re: Script to conditionally find and compress files recursively not@telling.you.invalid (Computer Nerd Kev) - 2024-06-14 09:06 +1000
          Re: Script to conditionally find and compress files recursively not@telling.you.invalid (Computer Nerd Kev) - 2024-06-14 12:25 +1000
  Re: Script to conditionally find and compress files recursively J Newman <jenniferkatenewman@gmail.com> - 2024-06-15 11:30 +0800

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