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compression

Lossless compression is a class of data compression that allows the original data to be perfectly reconstructed from the compressed data. By contrast, lossy compression permits reconstruction only of an approximation of the original data, though usually with greatly improved compression rates (and therefore reduced media sizes).
By operation of the pigeonhole principle, no lossless compression algorithm can efficiently compress all possible data. For this reason, many different algorithms exist that are designed either with a specific type of input data in mind or with specific assumptions about what kinds of redundancy the uncompressed data are likely to contain. Therefore, compression ratios tend to be stronger on human- and machine-readable documents and code in comparison to entropic binary data (random bytes).Lossless data compression is used in many applications. For example, it is used in the ZIP file format and in the GNU tool gzip. It is also often used as a component within lossy data compression technologies (e.g. lossless mid/side joint stereo preprocessing by MP3 encoders and other lossy audio encoders).
Lossless compression is used in cases where it is important that the original and the decompressed data be identical, or where deviations from the original data would be unfavourable. Typical examples are executable programs, text documents, and source code. Some image file formats, like PNG or GIF, use only lossless compression, while others like TIFF and MNG may use either lossless or lossy methods. Lossless audio formats are most often used for archiving or production purposes, while smaller lossy audio files are typically used on portable players and in other cases where storage space is limited or exact replication of the audio is unnecessary.

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  1. B

    Compression fitting advice

    Hello, I'm considering fitting an isolator valve to 15mm feed to my toliet cistern. It would require cutting off an existing compression fitting for a flex hose, after which I'd only be left with maybe an inch and a half of pipe. I've never fitted a compression fitting before, can someone...
  2. A

    Compression fitting loose on the pipe

    Hi, I am replacing a leaking push fit flexi tap connector under the bath with a compression fitting flexi. The problem is that the old pipe seems to be slightly smaller than 22 mm compression fitting and when I tighten the compression nut the whole fitting is easily sliding off the pipe and...
    • Alex_nv
    • Thread
    • compression fitting leak
    • Replies: 1
    • Forum: DIY Plumbing Forum
  3. K

    Shower valve advice - which 1/2 adapters should I use?

    Hi all I'm in middle of my bathroom renovation and about to connect up the shower valve. Thus far I've run all copper but would you recommend I use soldered to 1/2 adapters in to the valve or compression fitting to 1/2? Obviously I'd need to pre-solder the adapter before installing the 1/2...
  4. ian.

    Honeywell 10mm TRV compression inserts wanted

    I have Honeywell Valencia TRVs 10mm pipe size, I’m making mods to accommodate larger rads and it looks like the 10mm compression insert is special to Honeywell as all available inserts are 15mm to 10mm which do not fit as the compression nut has a 10mm hole, not a 15mm. Anyone know if you can...
  5. K

    PTFE tape or liquid / paste for compression fittings?

    Hi all I often find using ptfe tape with compression joints quite fiddly for my old hands, particularly in tight spaces. I was wondering if the ptfe liquid paste is a viable alternative? Does anyone on here prefer it? Thanks.
  6. J

    Leaking compression joint with plastic pipe.

    Yes, it me again. I have a leaking compression joint that is connected to plastic pipe. I have now read elsewhere that it is not a good idea to connect plastic into compression joints. It DID have an insert in the plastic pipe. I decided to use plastic JG speedfit pipe in the compression...
  7. J

    Compression fittings

    I need to replace the flow and return in the loft but using a torch is out of the question, is it wrong to do it entirely in compression? As don’t really like pushfit and press fit the cost doesn’t work out ?
  8. M

    Connecting radiator with compression adaptor

    Hello everybody! Just a quick question and hopefully you would be able to help. I have 2 radiator pipes, coming out from plasterboard wall, those pipes was prepared to be connected to radiator, once it will be hanged. My question is: Is it acceptable to use compression elbow fittings chrome...
  9. J

    How to tap off a 15mm compression to 1/2?

    While I am a trained engineer I appear blind when it comes to plumbing fittings. I want to tee off the 15mm compression (copper pipe to flex hose) to loo so as to supply a cold water bidet. The bidet is suppplied via a 1/2 connection. So appears simple, a tee but cannot find - any suggestions...
  10. K

    Is replacement boiler all compression fittings above boiler normal?

    Hi opinions please replacement boiler same location as old, descending water pipes adapted to fit with 3 compression fitting each so each has 2 90 bends, short horizontal pipes and a coupler. overall 6 fittings with 12 olives and 4 bends all above new boiler, previously straight unjointed...
  11. O

    How many turns when fitting compression isolation valve?

    I've never done one before and, as usual, Google is offering conflicting advice. I'm fitting one of these (from Screwfix, 15mm). I've read that ... Over tightening is the commonest cause of leaks. Once you've got it finger tight, you need to tighten a further half turn / full turn / one and a...
  12. F

    Compression onto brass solder meter union

    Hello I am having a massive argument with some guys over whether this is the correct procedure for these fittings. I have always been told (by gas college and gas coaches) that you do not use compression fittings on brass pipe as the olive doesn’t compress into the pipe. It’s not riddor but it...
    • Flipsy
    • Thread
    • america brass compression meter solder union usa
    • Replies: 1
    • Forum: USA
  13. D

    How To Join Pipe Thread (garden hose) To Compression (sink) ?

    I have a cold water sink in a shed a long way from the house. We just want to run a garden hose over to it and feed the tap from it. The tap of course has a flexible hose underneath with a compression thread fitting I guess. What sort of fitting or adapter do I look for so's I can plug my...
    • Deleted member 125263
    • Thread
    • america compression garden hose hose pipe sink thread usa
    • Replies: 2
    • Forum: USA
  14. Bogart

    Tight compression fitting

    Trying to get the 3 port valve off so I can get on with changing from Y plan to S plan. Problem is one of the compression treads will not come free. And being sods law it is the one feeding into the DHW tank. Have tried brute force with 2 large spanners, tried heating it, and freezing it and...
  15. M

    Zero Lead Brass Compression Fittings

    I understand that, at least in the USA, the term "Lead Free" means "not more than a weighted average of 0.25% lead when used with respect to the wetted surfaces of pipes, pipe lead-free compression fittings, plumbing fittings and fixtures." In other words, Lead Free does not necessary mean Zero...
    • mclintan
    • Thread
    • america brass compression compression joint fittings lead usa
    • Replies: 6
    • Forum: USA
  16. D

    Are support sleeves necessary for copper pipe compression fittings

    Hi, This must have been discussed in the past but with a quick search I couldn't find the answer I wanted. What is the view of using support sleeves inside copper pipes for compression joints. (The pipes in question are 28 mm and 35 mm diameter so I'd expect them to be pretty strong anyway.)...
    • davblo
    • Thread
    • america compression copper fittings necessary pipe support usa
    • Replies: 3
    • Forum: USA
  17. M

    Compression fittings

    Have noticed my success rate with compression fittings fall over the last year or so. Am getting a few that weep. When I back to nut off to have a look the olive isn't over tighthed and I always clean the pipe first. Wondering if anyone else has noticed this whether it's just me or the quality...
    • Matt0029
    • Thread
    • america compression fittings usa
    • Replies: 34
    • Forum: USA
  18. J

    To LSX or not on compression pipe fitting?

    Going to put in new iso valves and on the compression fitting should a smidgen of LSX be used around the olive? On the other end will be fitting tap tail adaptors again using olive and smidgen of LSX. https://www.toolstation.com/tap-tail-adaptors/p14081 So is there any downside in using LSX...
    • Justice League
    • Thread
    • america compression fitting lsx pipe pipe fitting usa
    • Replies: 11
    • Forum: USA
  19. J

    Solvent Weld vs compression waste pipe

    Does anyone have a preference to use solvent weld or compression fittings for waste pipes?
    • Justice League
    • Thread
    • america compression compression waste pipe solvent solvent weld usa waste waste pipe weld
    • Replies: 11
    • Forum: USA
  20. J

    Correct way to connect two compression fittings

    Apologies for the stupid question, I'm just a newbie playing under the sink. I have an isolation valve and an elbow, both of which have compression fittings that would normally fix to copper pipe. I need to connect both together directly. What is the correct fitting to do this? Surely I don't...
    • JackGr
    • Thread
    • america compression connect correct fittings usa
    • Replies: 6
    • Forum: USA
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