Ask MetaFilter questions tagged with compression

Sound Compression

Yakuman — Thu, 29 Oct 2009 04:31:14 -0800

Is there an audio plugin that will emulate the mono sound compression used by AM radio stations?

Compression socks recommendation

corpse — Fri, 16 Oct 2009 15:09:51 -0800

What brand compression socks should I buy? I'm looking to get some compression socks to aid in recovery after long runs. Also, I really like the overall feeling of compression clothing so I'll probably wear them around the house regardless of when my last run was.

There are a lot of brands out there of varying price levels, so I'd like some recommendations. I've been looking at Zoot, 2XU, CEP, Zensah, Oxysox, various medical compression socks and stockings. The less seams the better. Any recommendations?

Help me put my best e-foot forward

Jezztek — Thu, 08 Oct 2009 00:20:36 -0800

Facebook brutally compresses my images, anything I can do to minimize it? Howdy all,

I'm finally getting around to making a Facebook page for my t-shirt designs, but I have bumped into a problem:

I'm trying to upload images of my designs, which tent to feature large flat areas of solid color. Facebook's compression algorithm mangles some of these solid colored areas them pretty brutally. Example, check out the red in this image:

upload_compare.png

Are there any tricks out there to minimize this problem? Formats, modes, resolutions to save in that might help things? Adding subtle noise, or other tricks to force the algorithm to work a little harder? Alternative means of uploading that don't get the usual treatment? any tricks would be greatly appreciated!

Thanks much!

Help me Optimod-ize my audio!

CommonSense — Tue, 21 Apr 2009 15:35:46 -0800

Is there a good real-time compressor/limiter for FM broadcast that I can use on a Mac? Preferably one that works as an AudioUnit (AU) plug-in? I'm feeding audio for an LPFM station from iTunes over to AU Lab (which comes free with OS X's Xcode Tools), which allows you to run the audio through AU plug-ins, a variety of which come bundled with the Xcode Tools. They're pretty good, but I'd like to find something that really "punches up" the audio for FM broadcast.

Ideally, I'd like something that's an "Orban Optimod clone," the way SoundSolution does on Windows. It apparently has a reputation for being THE compressor/limiter plug-in, but it's only for WinAmp on Windows, which kinda sucks for me.

My Google-fu is failing me, and I keep coming across consumer-oriented software, which strikes me as glorified volume boosters. I can't seem to even find commercial software that accomplishes what I need. Hardware seems to be the only option, but that's not really realistic for me right now.

Is there any hope?

Best way to manage decryption/decompression of iPhone app bundle resources?

avocade — Wed, 04 Mar 2009 14:24:27 -0800

How to best encrypt and compress a folder of html-files in the iPhone app bundle, and unpack on first start? (DRM) My client wants to encrypt/compress the html-code for their medical books inside the iPhone bundle, to protect their IP.

Whats is a good way to prepare this file for the app bundle, and what complementary libraries (C, Obj-C) should I use to do the decryption and decompressing on the first launch of the app?

Copying the file to ~/Documents, then working on it seems like the best solution. Thoughts?

Compressing whole DVDs for playback on a Mac.

odinsdream — Sat, 21 Feb 2009 11:04:50 -0800

How can I store DVDs for use in a media library and get the benefits of compression without losing the menu structure and special features? I store DVDs on a Mac for playback with VLC or most recently Plex. Both of these programs will read directly from VIDEO_TS folders and display the normal DVD navigation screen so you can access special features, subtitles, all the audio tracks, etc.

I currently do one of two things: Use MacTheRipper to create a VIDEO_TS folder from a physical disc, or use Handbrake to extract only the main title and compress it into a single H.264 file.

The first method is good because it preserves the entire disc and all of the features on it. The second is good because it takes up only about a quarter of the space.

Is there a way to compress all the video on the disc and write it back to a VIDEO_TS folder, thus preserving all of the features of the disc but getting a smaller size?

I don't need these folders to be readable by standard DVD players.

compression

citybuddha — Sun, 28 Dec 2008 08:25:30 -0800

I am searching for a freeware utility for mac osx 10.3 and higher that can be used to compress files. Can't seem to find anything...

Which camcorders let you turn off all the clever stuff and access the raw video?

handee — Fri, 21 Nov 2008 08:30:24 -0800

I'm thinking of buying a camcorder. My requirements are slightly unusual: I would like one that does all the "bells and whistles" stuff (image stabilisation, auto light balance, H.264 compression etc). But I also want to be able to turn off all the clever stuff and access the "raw" video. Any recommendations? Hard disk/SD recording is a must, high definition would be good.

pondering Honda quandary

wsg — Wed, 19 Nov 2008 12:52:47 -0800

Is it reasonable for a 1995 Honda Odyssey engine with 150K miles on it to have a compression of 179? My old '95 Honda Odyssey's engine is worn out. I either need to buy another car or put an engine in the one I have. I'm not real car-savvy, so need to lean on the wise counsel of my friends here at ask mefi.

My funds are limited. I need something I can haul a little gear in, so a wagon or minivan is in order. I like 4-cylinders cuz gas prices are not going to stay low, I have a feeling. I can't get much of a car with my limited budget, but can afford an engine for the car I have.

I've been pricing engines locally. One salvage yard has one with 150K miles and compression of 179 for $500.00 w/90-day warranty. Installation is going to be about $800.00. When it's all done, engine and installation will be about $1500.00.

Another one is $2300.00 installed. This includes an engine with 79K miles and no compression rating available. Parts and labor warrantied for 1 year.

What's the better deal? Thanks.

DVD/Handbrake Divx Burning Woes

snap_dragon — Sat, 15 Nov 2008 15:59:36 -0800

I using Mac the Ripper than Handbrake to turn DVDs into mp4 files. (I use DVD dual layer)...When I use Roxio Popcorn, I can fit several movies on a disc (4) but it takes honestly a day and a half to burn on DVD !!!! But the DVD plays perfectly in my cheap player. Trying a different route, I tried dragging the mp4s to a blank DVD disc and then clicking "Burn" -- it burns and takes only 30-40 minutes but this version will not play on my DVD player. Anybody out there have an idea what I can do to make the process more efficient? Different software or different method? I appreciate your insight. By the way, I am running Mac OX X 10.5.5.

DVD Burning & Compression -- 2 for 1?

snap_dragon — Wed, 08 Oct 2008 04:02:37 -0800

I am using Mac the Ripper and Roxio Popcorn successfully to rip, compress, and burn DVDs. I have leftover DVD-R Dual Layer DVDs -- is it possible to fit to movies on a DVD? I tried a few ways and it only shows one movie. Any settings I could change? Any other software? Thanks.

What sort of inaudible audio signal survives compression?

Anonymous — Sun, 14 Sep 2008 19:25:40 -0800

I recently became an Arbitron ratings person (which I'm not allowed to tell anyone, hence my anonymity). I'm supposed to carry a portable device that they say picks up "sound energy" signals embedded by participating radio and TV stations so they know what I'm listening to, even if the audio is compressed. What the heck is "sound energy"? Here's what really has me confused: This "sound energy" (their term) is inaudible to humans. But according to Arbitron, their gadget even pick up the signal on podcasts or streaming internet radio. But doesn't audio compression work by (among other things) stripping out all the inaudible portions of the audio? So what's left for the device to pick up?

And what kind of "sound energy" can be picked up by the device whether I'm listening on high quality speakers, or a tinny transistor radio? And the device doesn't even need to be near the speaker. They say that if my ears can hear the radio, even from another room, so can the device.

So how the heck does this thing work? Is Arbitron overstating the efficiency of their device, or is there some magic technology at work?

How can I apply Dynamic Range Compression to my iTunes library?

Mwongozi — Tue, 02 Sep 2008 13:43:18 -0800

How can I apply Dynamic Range Compression to my iTunes library? We all know, of course, that Dynamic Range is usually a good thing. But when I listen to music in the car, much of my music has me cranking the volume up and down all the time to hear the quiet bits, and then avoid being deafened by the loud bits.

I have too much dynamic range.

What I want to do it make separate versions of some of my music which have had their range reduced so I don't have to drive with one hand on the volume control.

I'm on a Mac, and am aware that I can do this using Audacity (the "Compressor" effect) but it's a pain to have to rip to WAV, compress using Audacity, then convert to AAC or MP3 (and manually type in all the lost metadata).

What I really want to be able to do is to automate this during the ripping process, or, alternatively, find an easy way to compress existing MP3s or AACs without wiping out the metadata.

Any ideas?

How to unzip my iTunes Library backup?

wheat — Sun, 17 Aug 2008 10:43:12 -0800

OS X filter: How can I recursively unzip files (in directories that are not zipped)? One of my hard drives died, and took my iTunes Library with it (thanks, LaCie). Luckily, I have a backup (made with SyncBack while I was still on WinXP). I had zip-compression enabled in my backups, on a file-by-file basis. So what I'm left with is an iTunes library of uncompressed folders that contains individual mp3 files that are compressed (.zip, not .gzip). And, yeah, I know, compressing files that are already compressed is stupid, but it seemed like a good idea at the time.

I'm on OS X now, and I want to uncompress all of these and then drop them into iTunes. "gunzip -r *" doesn't work because they're in .zip (rather than .gzip). "unzip -r *" doesn't work because the directories are not also zipped.

Can anyone help me with a little shell script magic to traverse these directories and unzip everything? Or is there some other unzip utility out there that can handle this easily?

making podcasts easier to hear with dynamic compression

primer_dimer — Thu, 14 Aug 2008 02:02:01 -0800

Can I make podcasts easier to listen to in a noisy environment using compression? Calling all audio folks... I have a collection of podcasts (currently working my way through TED) to listen to on my boring commute, either by motorbike or car, both of which are quite noisy. Obviously I don't just want to crank up the volume on my mp3 player, for fear of damaging my hearing. So I'm wondering if I could use compression (of the dynamic kind, not the wav->mp3 file size kind) to even out the volume throughout each track and therefore make it easier to hear what's being said at a lower volume. This would be particularly useful where there are multiple people talking with different voices (e.g. radio 4's In Our Time, another current favourite). Will this work?

Ask a chemist - cooling CO2

gspm — Thu, 24 Jul 2008 14:51:12 -0800

A question for chemists - I am doing a calculation about the energy requirements of taking CO2 at atmospheric pressure and temperature and compressing it to 2 MPa (2000 kPa, about 300 psi) and cooling it to -31ºC and am a bit uncertain about handling the phase change from gas to liquid. The 2 MPa, -31ºC is the IPCC's state for transport of CO2 by road or rail tanker.

I've assumed an isentropic two-stage compression to get to 2 MPa.

I've calculated that the gas would be around 140ºC after the compression is complete. So, one can assume that no energy is required to cool to atmospheric temperature. But to cool it further would require refrigeration... and then there is the phase change (heat released going from gas to liquid?).

What do I need to do to calculate the energy required for that 2 MPa at 25ºC to 2 MPa at -31ºC step?
∆h = cp∆T but what about the phase change? (I knew how to handle this, once, long ago)

How to compress a bunch of folders to their own zip file?

niwnfyc — Mon, 07 Jul 2008 09:22:47 -0800

Is there an automated script or program to create a separate zip file for each directory? I have around 100 folders within "C:\Projects", and I would like to take each of those folders, and compress them into their own zip file:

Example:

C:\Projects\Folder1\ -> C:\Projects\Folder1.zip

The folder's are all different names, so I can't make an easy loop script (i.e. loop from Folder1 to Folder100)

Is there an automated script, or program that I can just select the root directory (C:\Projects), and it will loop through and convert all the directories for me without me having to manually select or type out all the directory names?

Should I buy an eee PC?

smithmac_99 — Fri, 27 Jun 2008 13:01:59 -0800

How do I get DVD video onto a optical driveless PC? So I'm thinking about getting one of those mini laptops such as an ASUS eeePC or some such. My main concern is the lack of an optical drive. I think it's a little silly to buy an external optical drive that you have to lug around with you if you want to watch DVD's.

So actually, I have a couple of questions and if you own one of those eees, I'd love your input.

1) Is it possible to compress a DVD movie on my mac, transfer it to a USB flash drive and watch it on an eee?

2) Does the battery life on one of these computers even make it possible to watch a movie while travelling?

3) The new eee 1000H actually can be configured with a 80gig hard drive. Would this be the way to go over one of the smaller ssd drives?

4)I'm a total linux retard. Is it tough to learn? Should I get one with XP? Will my mac play nicely with both or either?

Thanks for your help!

How common is familiartity with .ZIP archives?

unmake — Wed, 18 Jun 2008 03:22:36 -0800

Is it safe to assume that anyone professionally employed in a computer-using job (secretary, assistant, ect.) is familiar with ZIP archives? What about the public at large? I was using LHZ almost 20 years ago, but most of my (less technically-inclined) friends have acquired their computer literacy in a more casual/disinterested manner - I cut my teeth on a lengthy textfile CLI tutorial that covered this stuff; I'd imagine it's covered by whatever courses today's 16-22 year-olds have to take, but how did contemporary ~30+somethings figure this stuff out, assuming it wasn't covered in the rudimentary computer courses we took (think: classrooms full of IBM PS/2's, Windows 3.1, and the LOGO turtle)..

This question is probably more applicable to Windows users, as Mac's tend to decompress archives to the Desktop by default.

Compression software for a Flip Ultra

lometogo — Sat, 26 Apr 2008 13:54:43 -0800

I have just bought a Flip Ultra but the included compression software to make large video files email or YouTube ready is unbelievably slow. I'm on a PC, running XP. Can you recommend any third party compression software?

Streamline a conversation

colecovizion — Thu, 24 Apr 2008 14:49:54 -0800

Outlook Cleaning/Archive Gurus: Help me eliminate emails with similar (but not duplicate) content! I'm having a hard time finding a way to automate the search and deletion of emails with similar content. I have a manual process that I'm trying to automate.

The method: Every time an email is responded to, the full text is usually retained from the previous response.

Example (without attachments):

* Person #1 sends email
* Person #2 replies to email (includes the first email's full text)
* Person #1 replies to email (includes the first two emails)

Why not just keep the latest response in the conversation and any emails that have unique attachments? This way, you can reduce the Outlook size without compromising any data! Of course, this gets more complex with multiple recipients and responses.

The setup: Let's assume 1000 emails are in 1 giant archive folder. These emails include my sent email and my received email that are ready for archiving. Hence, my manual process....

* Sort by conversation (more often than not, the email text in the body is duplicated each time there is a response)
* Delete the oldest emails within a conversation UNLESS there is a unique attachment or unique text that isn't already in a newer email

In a world without attachments, this would usually keep the most current email in the conversation (which has all of my replies and their replies).

I know this is a very specific request, however, I think this method is pretty snazzy (to blow my own horn here) because it keeps all the unique information and it eliminates the duplicate information. Hence, smaller backups and better searches.

Any guidance is appreciated! Also if you have any Outlook email tricks please post for all to see!

How do I open a ".tar.tgz" file?

exolstice — Sat, 29 Mar 2008 05:31:19 -0800

How do I open a ".tar.tgz" file? That's all one long extension. I have a friend who's hosting package expired on www.canaca.com. So I immediately logged-in to backup his information. The problem is the backup function gives me a huge file with a .tar.tgz extension. Now I would like to take the contents of that file and upload to my own hosting service. I tried uncompressing with WinZip, WinRar, WinAce, ZipGenius, StuffIt, Gzip, GUnzip, and more! None of these programs recognize the file as a valid archive. I uploaded the file to my hosting service, and attempted to extract it from there. Same result. I also redownloaded the backup, thinking the original file may have been corrupted, but I got the exact same file down to the byte.

They seem to have disconnected the ftp access, so I can no longer access the files that way. The backup function is my only option.

So am I stuck with a proprietary file which can only be uncompressed on www.canaca.com or is there another way to crack this nut?

Thanks!

Batch image compression on Windows Server?

bloodniece — Tue, 04 Mar 2008 08:02:59 -0800

Can anyone recommend a small/lightweight image compression program that can run on Windows Server 2003? Thanks We are archiving large amounts of jpeg and tiff files but want to leave behind lower resolution reference images. Is there a program that you can say, right click over a folder and compress the entire contents of said folder?

uncompress my love, cause maybe i dont love you all that much

yonation — Sat, 09 Feb 2008 11:26:09 -0800

compressed files inside of compressed files inside of compressed files. arg. please help me automate this process. i have one large RAR file, with many ZIP files in subdirectories in this file. inside the ZIP files, there are further subdirectories leading to... a RAR file. this end RAR file contains the final jpegs i need. can anyone please make the process of unpacking these end RARs (literally hundreds of hem) into some sort of managable directory structure? [oh and i'm on Vista]

Downgrading Megapixels

lullabyofbirdland — Thu, 07 Feb 2008 08:00:27 -0800

Stupid-question-filter: Suppose you have a 10 MP camera and take your pictures at 3 MP. Would the quality be any different than if you were using a 3 MP camera at its top setting? (assuming the two cameras are otherwise identical) Also: Do any image compression formats do a better job of reducing file size while preserving image quality than just taking a picture at lower resolution would?