Many audio and video files are compressed. That is often necessary, because otherwise you are stuck with overwhelmingly large files. You may need to install the correct codecs in order to play them. We explain here how that works.
Compression is done using special software called codecs. That term comes from compression-decompression according to some, and encoding-decoding according to others. Well-known ‘lossy’ audio codecs (the quality of the sound decreases slightly) are for example mp3, wma, ogg and aac. There is also such a thing as ‘losless’, meaning lossless compression, such as flac, alac, and ape, and there are even codecs that do not compress at all, such as pcm in wav files.
Also for video there are both lossy and lossless codecs: a comprehensive overview of all codecs can be found on Wikipedia. In order to play an audio or video file, your media player must be able to handle the codecs used. The free open source media player VLC player is known for having built in a rich arsenal of codecs. Windows Media Player is less well equipped in that regard.
Which codec?
It’s free MediaInfo can tell you exactly which codecs an audio or video file contains. After a one-time installation, where you place a check at Shell extension […], all you need to do now is right-click on the media file and MediaInfo to see all information.
audio compression
When multimedia files are compressed, it may not be so bad if they lose some quality as a result: with a few modest artifacts in video or a slightly less full sound, you can still live. Certain information is omitted – which, by the way, can no longer be retrieved -, and that always implies a certain loss of quality.
In order to limit that loss of quality as much as possible, codecs usually mainly omit the frequencies that the human ear cannot pick up anyway (psychoacoustics). Below you will find an audio test that illustrates this nicely, with sound between 20 Hz and 20 kHz.
In addition, high-frequency sounds (15 kHz and above) are often difficult to hear when accompanied by louder, lower-frequency sounds. Codecs in this case often use ‘masking’ by cleverly omitting the high-frequency sound.
Bee The Ghost In The MP3 you will find the test results of an interesting study. This includes an audio sample of “Tom’s Diner” (Suzanne Vega) with the sounds filtered out by a 128 kbps MP3 file (see example 8) from the uncompressed original (see example 6).
Install codec pack
We already said it: your media player or device must be able to handle the codecs used in order to play the audio or video. Sometimes a software or firmware update can help, or you can install the necessary codecs using a codec pack, such as K-Lite. on Codec Guide you see exactly what the various versions (Basic, Standard, Full, Mega) of K-Lite contain; you decide which decoders you install.
Keep in mind that VLC Player cannot handle this codec pack; if necessary, choose the Standard edition that includes a suitable player (MPC-HC). If you can’t get a video or audio to work, there’s always the option to convert or transcode a media file. In other words: using other codec(s) and/or converting them to another container format (read: with a different file extension).
Convert video with Handbrake
As for free video transcoders, comes handbrake in the crosshairs. It is ad-free, open source freeware with many detailed options. The tool is available for Windows (64 bit), macOS, and Linux, but isn’t the fastest in the class.
At startup you can choose between a complete Flyer or a single one traffic jam. You can choose from numerous ‘presets’, but you can also set all parameters yourself. On the tab Summary sets you the desired format alias in the container (MKV or MP4), after which you click on the Video and audio denotes the video and audio codecs, respectively. Depending on your choice, you will find additional options here such as Frame rate (FPS), Quality and Avg bitrate. You get additional feedback when you hover the mouse pointer over such an option.
Click preview, Live Preview to view and listen to the result (after the preliminary transcoding) based on your settings. Through Browse determine the target location and with Start Encode start the final (trans)coding.
Convert audio with VSDC Free Audio Converter
After all, there are also many converters for audio files. One of the better free tools is VSCD Free Audio Converter. Make sure that you do not install any unwanted extras during the installation.
You first retrieve all the desired audio files, you determine the target location and then you indicate the intended audio format: mp3, wma, aac, m4a, amr, ogg, au, aiff or wav – so plenty of choice. A number of profiles (presets) are now automatically available with quality indications such as Highest, High, Normal, Least and mobile.
You don’t have to use these though; via the button Edit profiles you can add your own profiles based on all sorts of options, such as Audio bit rate, Frequency and channels. Once you have chosen the desired profile, you can start the conversion by clicking Convert files to click.
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