Compress Large Files

Compressing files in modern operating systems is usually pretty simple, but things can get more complex when the files are large. If the files are too big, you won't be able to use your operating system's built-in compression software. Luckily there are programs available that can compress files of any size, and with the right settings can potentially reduce the file size by quite a bit. If you're trying to get your media file sizes under control, there are a variety of formats for images, videos, and audio that allow you to compress them without suffering too much quality loss.

Steps

Before You Start

  1. Understand that not all files can be compressed by a significant amount. Compression works by replacing sets of characters within a file with smaller, placeholder characters, resulting in a smaller file size. Not all files lend themselves well to compression, and you may not be able to compress a file much smaller than its original size.
  2. This guide is for compressing files too large for standard compression software, as well as compressing media files. If you want to learn how to compress multiple files into a single compressed archive using your operating system's software, click here.

Using Compression Software for Large Files and Folders

  1. Download an alternative compression program for files larger than 4 GB. The built-in compression software on most operating systems will cap out at 4 GB of data in a single ZIP file. If you need to compress a file that's larger than that, you'll need to download and install a third-party compression program.
    • Keep in mind that if you're sharing your compressed files, the recipient will need a program that can open the type of file you create.
    • 7-Zip is one of the most popular open-source options for Windows. You can download it for free from 7-zip.org/download.html.
    • WinRAR is a powerful paid program for Windows and Mac that can perform very efficient compression.
    • Archiver is one of the most popular Mac compression programs that allows you to create archives in 7-Zip and RAR format, as well as its own proprietary format.
  2. Adjust your compression settings. With their default settings, 7-Zip and WinRAR will typically compress more efficiently than your operating system's built-in compression software. You can increase the compression even more by adjusting some settings.
    • 7-Zip - Right-click on the file or folder you want to compress and select "7-Zip" → "Add to archive". In the "Add to Archive" menu, you can set your compression options. Note that increasing compression levels can significantly increase the time it takes to compress. For maximum compression, set "Compression level" to "Ultra". Set the "Dictionary size" to a value ten times lower than your available memory. A larger dictionary means better compression, but the memory requirements are ten times the dictionary size. Set "Solid Block size" to "Solid" for the best compression.[1]
    • WinRAR - Right-click on the file or folder you want to compress and select "Add to archive" with the WinRAR logo. Note that increasing compression levels can significantly increase the time it takes to compress. In the General tab, select "Best" from the "Compression method" drop-down menu. Ensure "Dictionary size" is set to "5096 KB". Check the "Create solid archive" box. Click the Advanced tab and then the Compression button. Set "Text compression" to "Auto".
    • Archiver - Archiver doesn't have as many settings as its Windows counterparts, but you can set the compression level when creating an archive. Note that increasing compression levels can significantly increase the time it takes to compress.
  3. Split a large compressed file into multiple smaller files. One of the benefits of using a third-party compression program is the ability to create a multi-part archive. For example, you could take a 12 GB folder and split it into three smaller files that could each fit onto a DVD. You'll need all of the parts to extract the original files, so make sure you don't lose any of them.
    • 7-Zip - When in the "Add to Archive" menu, you can use the "Split to volume" drop-down menu to select from a variety of preset sizes. You can also type in a custom size. Each part will be the size you designated, with the last part being whatever is left over.
    • WinRAR - In the General tab of the "Archive name and parameters" menu, use the "Split to volumes, size" drop-down menu to select the size you want each part to be. You can also type in custom sizes, and use the second drop-down menu to designate the unit (byte, kilobyte, megabyte, etc.). Each part will be the size you designated, with the last part being whatever is left over.
    • Archiver - Click the "Split" button in the Archiver menu after adding a file. Set the size that you want each part to be. You can then set the compression settings for the file.

Compressing Large Video Files

  1. Download Avidemux. This is a free, open source video editor that allows you to easily compress and convert your video files. You can download it from fixounet.free.fr/avidemux/. It is available for Windows, Mac, and Linux.
    • Videos are large chunks of data that don't compress well when added to an archive using the method above. Instead, you'll want to re-encode it using Avidemux, which will lower the file size considerably at the cost of some quality.
    • Movie files that you've downloaded from online sources may already be compressed. Further compression can lead to a virtually unwatchable final product, or may not result in significant size changes.
    • It is not possible to uncompress a compressed video. You should always save the compressed version as a separate file so that you don't lose the original.
  2. Launch Avidemux and load the video file. You can click "File" → "Open" to browse for the file on your computer. It may take a few moments for the video to load.
  3. Set the "Video Output" drop-down menu to "Mpeg4 AVC (x264)". This is the most compatible format for your converted video.
  4. Set the "Audio Output" drop-down menu to "AAC (Faac)". This will compress the audio track of the video to keep the size down.
  5. Set the "Output Format" to "MP4 Mixer". This will ensure that the video plays on the most devices possible.
  6. Click the .Configure button in the "Video Output" section.
  7. Find the "Rate Control" section of the .General tab.
  8. Select "Video Size" from the drop-down menu. Enter in the target size for the converted video. Avidemux will adjust its settings to get as close to your target size as possible, but it may end up slightly over or slightly under the target size.
    • Note that setting the target size significantly smaller than the original size will result in a drastic decrease in quality.
  9. Click the "Save Video" button. You will be prompted to enter a name for the video, and then the conversion and compression process will begin. Depending on the length of the video and the quality settings, this could take quite some time to complete.[2]

Compressing Large Images

  1. Understand what can be compressed. Most images that you download online are already compressed. The file formats .jpg, .gif, and .png are all forms of compression, and further compression will lead to a sharp decrease in quality. Compression for images is most useful if you are working with images directly from a digital camera or .bmp files.
    • It is not possible to uncompress a compressed image. You should always save the compressed version as a separate file so that you don't lose the original.
  2. Understand the difference between "lossless" and "lossy" compression. There are essentially two types of compression for images: "lossless" and "lossy". Lossless compression is for cases where you need an exact replication of the original, and is typically used for drawings, diagrams, and medical imaging. Lossy compression is for cases where a drop in quality won't be noticed as much, and is most commonly used for photographs.
    • .gif, .tiff, and .png are all lossless formats.
    • .jpg is the most common lossy format for images.
  3. Open the image in the editor of your choice. Nearly all image editors support compression by allowing you to save the image as a different file format. When you choose a compressed format, you'll be given options to determine how much compression to use.
    • Photoshop, GIMP, and even Paint allow you to save image files as compressed formats. Virtually any image editing program will work, though some will give you more quality options than others.
  4. Click "File" → "Export As". This will allow you to save a copy of the original image using a new format.
    • If you're using Paint or another basic image editor, you will need to use the "Save As" option instead.
  5. Select your desired format from the "Type" menu. The format you choose has a lot to do with the nature of the image.[3]
    • If you're compressing a photograph, select .jpg as your format.
    • If you're compressing an image with less than 256 colors, select .gif as your format.
    • If you're compressing a screenshot, a drawing or comic, or any other non-natural image, select .png.
    • If you're compressing an image with layers that you want to preserve, select the .tiff format (note that .tiff format isn't necessarily considered compression).[4]
  6. Set your quality options (if possible). Image editors like Photoshop and GIMP will ask you to select your quality and compression settings after clicking the Export button. You can typically use a slider to adjust the compression or quality.
    • Increasing compression (decreasing quality) will result in a much smaller file size, but will add a lot of artifacts and change the color of the image. You may need to play with the options to find a good tradeoff between quality and size.

Compressing Large Audio Files

  1. Understand what can be compressed. Most audio files that you download from the internet, such as .mp3 or .aac files, are already compressed. Further compression of these types of files will typically result in a poor-sounding file. Compression is best suited for uncompressed formats such as .wav or .aiff.
  2. Download Audacity. This is a free, open-source audio editing program that is available for Windows, Mac, and Linux. You can download it from audacity.sourceforge.net/.
  3. Open the file you want to compress. You may be prompted to copy the file into your Audacity project; this will help prevent you from saving over the original.
  4. Make the file mono (optional). This isn't recommended for music or anything with essential stereo effects, but for spoken voice or other recordings that don't require high-fidelity, switching to mono (single-track) can make the file significantly smaller.
    • Click the ▼ next to the file's name in the project area. Select "Split to Mono" from the menu.
  5. Click "File" → "Export Audio". This will open a window allowing you to set where you want the file to be saved, as well as the format you want to use.
  6. Select your compressed format. All of the formats listed in the "Save as type" menu are a form of compression, except .wav and .aiff. The format you choose depends on your requirements.
    • .mp3 is the most common format for music, as it allows for good compression without too much noticeable quality loss. it is also compatible with virtually any device.
    • .flac is a lossless form of compression. It is good if you intend to playback the audio through a high-quality sound system, but it is not compatible with many devices. .flac will also not lead to a drastic reduction in file size.
  7. Click the .Options... button to set your compression settings. After you've chosen your format, click the Options... button. The options available will vary depending on the format you selected.
    • For .mp3, a lower bitrate will result in a smaller file but will reduce the quality of the audio. 128 Kbps is about equivalent to the audio quality of FM radio, while 320 Kbps is about equivalent to a CD.
  8. Export the file. If you made the file mono, you will be asked to confirm that you want to proceed. Audacity will convert and compress the audio, and the new file will appear at the location you specified.[5]
    • If you are making an /mp3 file and don't have the Lame codec, you'll be prompted to download it. Follow the instructions on the page to download and install the Lame codec. You may need to restart the Export process.

Related Articles

Sources and Citations

  1. ↑ http://www.altap.cz/salamander/help/7zip/dlgboxes_config/
  2. ↑ http://www.makeuseof.com/tag/compress-videos-send-email/
  3. ↑ https://litmus.com/blog/png-gif-or-jpeg-which-ones-should-you-use-in-email
  4. ↑ http://www.scanyourentirelife.com/tiff-vs-png-file-format-hurt-save-scanned-photos/
  5. ↑ http://www.videograbber.net/compress-audio-file.html
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