Ask MetaFilter questions tagged with compression

Who's compressing my JPEGs: Gmail, iPad, or WordPress?

Artifice_Eternity — Tue, 16 Apr 2013 08:29:42 -0800

The other day I discovered that some JPEGs I'd posted to my (self-hosted) WordPress blog had been compressed. The subject of my blog happens to be anaglyph 3D photos... and if the images are not saved at a very high resolution, a phenomenon called "ghosting" or "crosstalk" appears, where parts of the image that are only supposed to be visible to one eye are visible to the other eye as well. This can ruin the 3D effect. So it's important that my images are uploaded and posted with no added compression. The problem is that I don't know exactly where the problem occurred. Details below... These particular images got to my blog somewhat circuitously: after exporting them from Photoshop on my PC at a very high resolution, I attached them to a Gmail message... then I downloaded them to my iPad's photo gallery... and then I uploaded them to the blog via the iPad WordPress app. Upon viewing the posted images, I could see a very definite degradation of image quality.

What I'm trying to figure out is which step in the chain caused this. I've sent image files thru Gmail many times, and never noticed any compression, so I'm assuming/hoping that's not where it happened.

I know that Apple often has stuff going on under the hood of its hardware and software that isn't clearly explained to users (which is why I've been wary of the iPad, and have only started using this hand-me-down unit recently). So it's my prime suspect. I looked for settings that might control image compression, but couldn't find anything that mentioned it or would allow me to prevent it from happening.

Then there's WordPress. When I upload multiple photos using the WordPress Media Uploader on the PC, there is a message that appears that says "Crunching..." My research suggests that the original images are not being compressed during this process, but rather that multiple image sizes are being created. Ultimately I've decided to upload images from my PC by inserting them individually into posts; the Media Uploader seems to handle this without any visible quality loss. But what the iPad WordPress app may or may not be doing to my images is still a mystery to me.

I'd really like to know where the problem occurred. It would be nice to be able to upload stuff from the iPad to the blog -- if this unwanted compression can be eliminated. I'm also thinking about buying the iPad Camera Connection Kit... but I don't want to try moving photos from my cameras thru the iPad to email or cloud storage, if it's going to mess them up.

Can anyone shed any light?

Batch Changing iTunes BitRate for Existing Songs W/O Making Copy

snap_dragon — Thu, 17 Jan 2013 07:53:28 -0800

So, I definitely want to convert all my high bit rate mp3 songs in iTunes to a lower bitrate of 190. I have the bit rate setting changed in iTunes, and I know when I right click and choose "make mp3 copy" it does exactly that. BUT, I don't want the original around anymore in iTunes and don't want to manually go through and delete them or go into the folder to do that. The threads I have looked at tell me how to do the first but don't address the issue that I still have the higher bit-rate copy in iTunes. I have a lot of music, I don't want the higher copies cluttering it. (I have a backup of the originals anyway). Is there something I am missing so it just lowers bitrate but doesn't make it a copy?

How to automatically degrade jpg quality to fit in a given space

Infernarl — Fri, 27 Apr 2012 17:44:37 -0800

How can I compress/resize thousands of jpgs to fit exactly into the space of a DVD automatically? I have about 10,000 scanned notebook pages saved as jpgs. The average size per file is 1.5mb and the average resolution in 2000px x 3000px. Is there some way to automatically compress the images so that they will all fit exactly on a DVD? The images are largely handwritten notebook pages. I am on a mac and I have Photoshop and Toast but would be willing to buy software to do exactly this thing. This is an ongoing project and the number of files will increase at some point (Think dvd version 1, version 1.1 etc). Ideally I would be able to compress/resize the images from the masters and produce a disk image that I could then burn on to multiple DVDs. These DVDs will then be given to people for viewing on regular home computers. The files are organized in to folders based on notebook volume with an average of 100 files per folder. What is the best way to do this?

Properly compressed current jazz and blues?

thrasher — Wed, 25 Apr 2012 08:12:14 -0800

What are your favorite current recordings with good dynamic range, preferably jazz and blues? I love blues, jazz/swing/standards, and roots-based rock & roll. Stuff like Lightnin' Hopkins, John Lee Hooker, Howlin' Wolf, Willie Dixon, practically everything the Nat King Cole Trio ever recorded, The Ramsey Lewis Trio, most rockabilly and 50's rhythm and blues, I'm a huge fan of the White Stripes and I like some of the blusier Black Keys stuff I've heard.

What recent stuff (say, last 20-30 years) should I be listening to that intentionally is not over-compressed, super-loud and destroyed? Any old stuff that you care to mention that I have probably missed is more than welcome too.

Gah! Acrobat!

halseyaa — Thu, 09 Feb 2012 07:45:51 -0800

Why is Acrobat artifacting my images? I am at my wits end. I have been trying to fix this for a long time to no avail (and have read all the unhelpful boards over at Acrobat's site and some other sites). Please help me, MeFis.

Basically I create beautifully sharp images in Fireworks (133 dpi) and they export into nice, crisp flat PNGs (32). But when I bring them into Acrobat Pro to create a PDF, they look horrible.

For reasons I won't get into here, the parameters are:
• My Fireworks exported images must be PNGs (not JPGs, although I tested that and they are better, but not by much)
• I must use Acrobat to create the PDF (Not Preview or any other software)

Its hard to see but here is an attempt at showing you what is going on (PIC). Note that the color is a little off and it is drawing a thin black smudgy line around the orange box that shouldn't be there.

I have tried changing the display settings but that 1. doesn't work and 2. wouldn't help the recipient view it unless I ask them to change their settings as well

Its obviously trying to compress them or something. Can't I just tell Acrobat "no thanks, I like my file sizes large and my images perfect"?

I will attempt to threadsit and answer questions as I am under the deadline gun on this one. Thank you, thank you!!

Looking to unPaq files

sagwalla — Sat, 21 Jan 2012 11:44:40 -0800

I am looking for information about decompressing "MediaPaq" archives, with .paq extensions. I am finding the Internet surprisingly silent. In a move to cloudify all of my old media, I finally gave in and bought a Zip drive on eBay to help me upload all my old Zip disks. Perfect. All uploaded, problem solved.

But not quite...

Two of the disks have files in .paq format that came from a package called "MediaPaq" or "MediaPack". It was a means to compress and store photos etc. Bad idea.

So, I've got a lot of my early digital photos .paq'ed up and would like to get them back. Windows says that .paq files are HP restore files, but these aren't those. I can't really find any other good information about how to unpack these. I would even settle for having the app itself that encoded them, so I could run it and unpack them back to whatever they were before. I tried changing the extension to .zip but that didn't fly.

Upside - I did find my first-ever digital photo, taken in March 1997, which I had not compressed. It was a picture of a tray of ravioli air-drying on the stovetop in my old place in Chicago. I had a tin of Guinness on the go.

How can I compress my portfolio into something that won't load like a bad animated GIF?

This_Will_Be_Good — Sun, 20 Nov 2011 20:26:26 -0800

Can somebody please explain to me image compression, specifically with regard to creating smallish PDFs from Indesign files that contain large linked vector graphics? No matter how many times I think I have a grip on compression and resolution and all of those terms, I still end up creating enormous files with no idea what is controlling what.

I am creating a portfolio in InDesign CS4 in which I have linked a lot of large files, mostly Photoshop files and a lot of very large Vector graphics (AI files). From InDesign, I will export the file as a PDF, using the High Quality preset for example. These files are huge, but are lovely when I print them. However, if I want to email a PDF to someone or create a smaller version, I have no idea how to compress these things.

If I try to optimize the PDF or export using settings as low as 72ppi, the file sizes are still huge and the vectors seem to load almost like animations. It seems the large vector drawings are the problem, but I can't seem to figure out how to "flatten" those without making the normal text in the file look terrible. The best option I have found so far is to just export the whole PDF as images, and then recombine into a new PDF but even these are pretty big and the regular text (captions, titles, etc) look a little gritty.

I guess I am not sure where in this process I should have been scaling down the large vector images or even the original PSD files (I was under the impression that these originals should stay uncompressed). Should I have scaled down the original images? Should I have changed some setting in InDesign? Is there a secret setting in Acrobat for vector images only that I can't find?

Please help me figure out what is controlling what, and help me avoid having to hire a courier to carry over a stack of flash drives instead of just emailing a nice, neat PDF.

Rip Blu-Ray straight to uncompressed .avi at 1080p. What's the best way to do it?

Cool Papa Bell — Fri, 23 Sep 2011 10:02:01 -0800

Rip Blu-Ray straight to uncompressed .avi at 1080p. What's the best way to do it? Details inside. I'm using Scaleform for media presentation. I want to go from Blu-Ray to .avi to .usm* with the fewest number of compression steps (i.e. I don't want to compress something already compressed, and if I have to, I want the first compression on the rip to be as lossless as possible).

I cannot find a tool that will rip a Blu-Ray at 1080p without doing some form of compression on the rip (e.g. DivX, Xvid, msmpeg4, H.264, etc). I want to compress once, not twice.

* My understanding is that this is required -- the Scaleform video encoder wants to start with .avi and nothing else. But please correct me if I'm wrong.

And yes, I know I will end up with monstrously huge files when I do this. That's not really a deal-killer in this instance.

Baby Got Back

Terriniski — Sun, 31 Jul 2011 07:03:18 -0800

Aside from preventing chafing, what are the benefits of compression shorts for running? Are there drawbacks? When I first got into running about 1-2 years ago, I bought compression shorts to help with chafing issues. They work great for that and I've been very pleased. There have been a few times where I've ended up running without them, and chafing issues aside, there was a different feel to running. Thighs/butt jiggled more, which seems pretty obvious, but for some reason that made it feel more difficult. I recently got a running skirt, and that takes care of the chafing issue, although the shorts under the skirt don't have the compression that my regular compression shorts do, so I still feel a bit of increased difficulty running in the skirt compared to the compression shorts.

Is one option better for me? Do compression shorts do something to make a run easier, which means that my body is doing less work and I'm sort of cheating? Or is the perceived difficulty just psychological?

Name of paper storage program?

This, of course, alludes to you — Tue, 12 Jul 2011 12:02:16 -0800

There's a kind of 2D barcoding program that stores large amounts of compressed information on paper, like a QR code. What's it called? I need to know what it's called. It's not Rainbow Storage, but it's kind of like that. If I recall correctly, it was monochrome and grid-based.

The article, as I remember it, said that it was specifically for archiving large quantities of information, and I think there was a freeware tool to use it linked on the page.

Realtime Recording to a Jump Drive

jmsta — Thu, 23 Jun 2011 08:52:06 -0800

What software will allow me to record from a FireWire source directly to a compressed format that I can deliver to workshop attendees? We will be hosting a Radio/TV workshop participants will be doing exercises at different stations where they will generate both audio and video content. They will rotate through these stations quickly. Each participant will have a jump drive that they will give to the administrator of each session. Their session will be "recorded" to the jump drive and then they will take the drive with them to the next session...Rinse Repeat..

I'm OK with the audio sessions recording directly to MP3 but what is the best software to use for the video session? The video files will end up being 2 - 5 minutes long.

The easiest workflow that I can think of that will generate a widely compatible compressed file is to use Windows Media Encoder Its easy to setup a recording profile and easy to record the compressed video directly to a file in real time.

I'm not sure this is the best way so if any one has other workflow recommendations I would appreciate hearing them

Science: Sound, Percption, MP3, and Beyond

waxboy — Thu, 10 Feb 2011 19:50:28 -0800

I'm in need of graduate level schooling on psychoacoustics and audio compression on the cheap. What are the latest and/or most used textbooks on these topics? There are two studies involved here: the science of how humans perceive sound and the art of data compression algorithms. My aim is to understand the state of the art in the overlap of the two with an emphasis on psychoacoustics, which may very well require reading up on each topic separately. Regarding psychoacoustics, I'm looking for the most comprehensive text(s) available. Something that discusses and illustrates concepts would be good. Something that specifies the math behind various models and refers to journal publications would be ideal. Regarding compression, math/reference heavy is preferred, and I'm primarily interested in techniques and algorithms that take advantage of psychoacoustic models to exploit frequency/loudness thresholds, phenomena like temporal masking, etc. Learning the various ways to perform related transforms such as FFT, wavelet, etc is also within my sights. The idea is to gain an understanding of, say, the science behind MP3, then and now, plus the challenges/limits involved in furthering similar technology.

What is the best audio compression for ipod quality earphones?

Fluffy654 — Mon, 10 Jan 2011 15:15:48 -0800

What is the best audio compression for ipod quality earphones? I don't want to buy expensive earphones and I will listen to music mostly through ipod earphones or earphones of a similar quality. I want to get the best possible listening experience but have heard it said that lossless formats are wasted on low quality equipment. I would like the smallest possible file size without impacting on music quality.

Will I notice much difference if I use lossless over lossy compression? Either way, what would be an appropriate compression format, given the equipment restriction?

Simple VHS digitization that still satisfies a video nerd's lust for quality

tweebiscuit — Tue, 14 Dec 2010 00:28:30 -0800

This year for Christmas, I'd like to get my parents the gift of converting all their VHS tapes to digital format. I'm a sometime video editor and effects artist, so I need a solution that's a) cheap, b) not too involved, workflow-wise, and c) meets my video nerd half's demand for quality. What's the best solution that fits all three? I just want my parents to have digital copies of the video on the tapes: we don't need to edit the footage. So I'm guessing that high-quality H264 is my likely final target format.

Tooling around on MeFi, I've found a few options:

1) A DVD recorder. These are also a bit pricey; worse, DVDs are a dead format, and the DVDs themselves would have to be backed up in a few years time anyway, as DVD-Rs don't last that long, and I know from experience that MPEG-2 is a pretty inefficient compression format.

2) The various Canopus converters. Most of these are more expensive than I'd like to pay, and I'm guessing that I'd have to first capture the tapes to DV (or other high bitrate format), then transcode to H264, which seems like a hassle -- I'm going to be digitizing a few dozen tapes over the holidays, and I'd rather be eating cookies than spending all my time wrangling video.

3) A push-button consumer solution. Cheap, but many of them produce very low-quality video. The best-reviewed I've found so far is the Elgato Video Capture Device. If the quality produced is up to snuff, this looks like the sweet spot -- it's easy, flexible, and produces H264 -- but I'm concerned that the fact that cheap and done over USB will mean that the video quality will be poor.

So: Does anyone have any experiences, good or bad, using the Elgato? Basically, I'm looking for video good enough that I won't see any compression artifacts at full resolution.

Thanks!

ow. ow alot.

Baby_Balrog — Sat, 13 Nov 2010 23:03:04 -0800

Relief for cervical ulnar nerve compression? It may be a few days until I can see a doc. I have whiskey and ibuprofen, but how should I sleep? My brother says to sleep with no pillows, my roommate says "sleep however it's most comfortable." I can't sleep at all. The pain is insane. I feel like my arm is being pulled off with a winch. I have an over-the-door neck traction kit which provides a few moments of relief. As soon as I take it off, my right arm is being set alight and it is bbq. It hurts so much I can't even describe it because I'm in too much pain to think about good descriptive words. Please, metafilter, have a thing that I can do to make it stop hurting. It's definitely a cervical compression on the root of the ulnar nerve. No doubt. It's been a full week and I'm losing it.

Please to make smaller file!

amanda — Mon, 10 May 2010 11:23:57 -0800

Why doesn't the compress feature on my Mac actually compress the files? It creates a .zip file but it's usually only a couple hundred k smaller than the original. Does the compression utility work on the Mac? Basically, you right-click on a folder or group of files and can choose "compress" from one of the drop-down options. How handy! However, I've noticed that it doesn't really compress anything though it does make a .zip file. Today, I took a folder containing 77 mb of info (jpegs) and did the little "compress" thing and it compressed it to 76.5 mb. Not exactly what I'm going for. Searching help files isn't telling me much. Is it better to use a stand-alone utility or is there some setting somewhere that I need to alter or is my fundamental understanding of compression not right?

How to compress a line graphic video

Silky Slim — Sun, 18 Apr 2010 04:48:22 -0800

Any video compression mavens in the house? Is there a specific codec which excels in compressing line graphics? I'm trying to compress three videos for the web. The first two look fine, but the third looks absolutely awful. The ones that look fine are filmed, with actors; The one that looks terrible is entirely comprised of a line graphic and scrolling text. Upon compression, the bottom half of the screen looks blocky and jumbled... See here (uncompressed at right, compressed at left). I used H.264 encoding and 700 kbps, as instructed... But I also experimented with higher bit rates and quality, to no avail. I hope this is all the info that's needed, but please ask if you need any more...

An hour plus of HD in under one gig?

meadowlark lime — Sun, 04 Apr 2010 17:40:32 -0800

How do I make my ~70 minute HD video under 1 gigabyte? I have a project that I shot in an HD format (1440 x 1080 HDV, to be exact) that I've been working on for awhile, but only rendered to standard-def for delivery on formats like DVD.

Anyway, I'm now rendering out an HD version of it, and I'd like to know HOW people get long HD videos under 1 gigabyte? This is a size restriction for the place I want to put the video.

I know it's possible, because I've downloaded TV from torrrent sides where the video was, say, 45 minutes long and some 350 megabytes. (The video I'm talking about is not pirated material, I am just using those as a basis for comparison.) The torrent guys seem to be using the XviD codec... is this the right way to do it? Is there a better way?

Should I render the video out to .mp4 first and then compress it with XviD?

I'm using Sony Vegas.

I appreciate any help here.

Smallest possible audio file to make a 440hz tone?

scottreynen — Sat, 23 Jan 2010 17:45:12 -0800

I want to create the smallest (file size) possible audio file that, when repeated, will sound like a given note (e.g. 440hz A). I think this needs to be just the length of one wavelength, but I'm not sure how I translate that to a length of time, or if the smallest audio format is one in which note duration doesn't matter. I don't care if this tone sounds artificial, but it needs to play natively in Firefox, Safari, and Chrome browsers. Is MIDI the best (most compressed) format for this or should I use something else? And what (ideally free) software might I use to create the files, given access to OSX and Windows XP?

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.