HomeNo matter you are new or old hand to video conversion, you must understand some of the basic concepts need to do some limited video conversions like converting a 20GB MKV file to a smaller x264 MP4. Normally, it is easy to complete but there are many people just getting the question concerning that the huge file size difference between mkv files and mp4 files. Therefore, we provide the detailed explanation here and the best software to compress a 20GB MKV file to a smaller x264 MP4 with the best settings.
MKV File Size vs MP4 File Size
Both mp4 and mkv are "container" formats. This means that they can include video/audio/subtitle streams of different types, which can lead the size difference. For example, there may be an mkv version of a particular video that has a resolution of 1280x720, that is 7.0 GB in size, while at the same time, there may an mp4 version of the very same video, which also has a resolution of 1280x720, but it has a file size of 2.1 GB, or even smaller.
To convert a 20GB MKV file to a smaller x264 MP4, you need to consider about the each parameter. The first thing that you should check is the video codec that is used in each container; for HD video this will likely be AVC, with AAC audio. The next thing to check is the video bitrate; this is a measure of the amount of data that is used to encode each frame of video. Given the same framesize (resolution) and duration, videos with a higher bitrate will tend to take up more space and generally (but not always) give higher quality. Video bitrate is the other large factor. While it is a fair supposition to make regarding the larger file probably having higher quality, there are a number of factors that come into play when encoding that could mean the difference is not as large as you might think (the type of content being encoded), or factors with playback that mean the difference in quality is not as apparent (lower quality TV or upscaler etc.). So the actual difference will vary from file to file, and the difference it makes to the end viewer will be very subjective. In addition, when the MKV file is 20 GB, it often comes from a Blu-ray rip. Chances are it will have the original HD DTS audio, which can be up to a third of the file size. If the MP4 version has two channel AAC then the difference can be substantial.
Best Software to Convert a 20GB MKV file to a smaller x264 MP4
Pavtube Video Converter (review) is a free-to-try and lightweight compression software for video files, which can reduce the size of video files with minimal quality loss. This software can work with many popular video formats, such as MP4 (MPEG), WMV, FLV, AVI, MOV, MKV, ASF, MPG, RMVB (RM). You just need to load your 20GB MKV files and choose x264 MP4 video output. To get the smaller size, you can freely configure the video and audio settings: video codec, video bitrate, video resolution, video frame rate, audio codec, audio channel, audio sample rate and audio bitrate.
What's more, you also can trim the original 20GB MKV file to get smaller size MP4 video or cut off the unwanted video area. You also can split the while MKV file into several MP4 video parts by time or count. For Mac users, you can do the same video compression process on macOS Sierra with Pavtube Video Converter for Mac.
Steps to Convert a 20GB MKV file to a smaller x264 MP4
Step 1: Load 20GB MKV files
Click "File" drop-down option, then select "Add Video/Audio" or "Add from folder" to select the 20GB MKV file you want to compress. Or directly drag and drop the 20GB MKV file into the software. This video compressor supports batch conversion. So you can add multiple 20GB MKV files for saving time.
Step 2: Compress 20GB MKV file to H.264 MP4
Click "Format" and choose "Common Video". Here you can choose "H.264 video (*.mp4)". After you choose the video format, you can preview the video size in "Settings".
Compress 20GB MKV to smaller size h.264 MP4
Click "Settings" button behind Format bar, to open "Profile Settings" window. Comparing to video format, video resolution and bitrate affects video size more. In general, a higher bitrate and resolution will accommodate higher image quality and video size in the video output, therefore, you can compress 20GB MKV video size by changing video resolution and bitrate. Adjusting frame rate is also an effective way to resize video. In this step, you can compress 4k to 1080p or 1080p to 720p. Just have a try.
If you want to get much smaller video size, you also can trim, crop and split your MKV files. Click the "Edit" icon on the UI to open "Video Editor" window. Under the "Video Editor" window, switch to "Trim" tab, you can cut off the unwanted parts from a long 20GB MKV video to short ones. Just drag the slider bars to include the segment you want to remain, click the left square bracket to set start point, and click the right square bracket to set end point when previewing the video or directly input specific values to "Start" and "End" box. Finally, click "OK". To eliminate black bars and unwanted area of image, switch to the "Crop" tab.
By clicking the "Split" button under the file displaying list, checking "Enable" to enable it, and then you can split 20GB MKV file by file count, time length, or file size according to your own needs.
Step 3: Start 20GB MKV to x264 MP4 compression
When the 20GB MKV size is meet your need after all settings are done, just click the big red "Convert" button and the rest will be finished automatically by this 20GB MKV compressor. After a while, you'll get your 20GB MKV video files in smaller size with MP4 extension on your computer.
In this way, you not only can compress 20GB MKV to a smaller size MP4 video, but also can convert large MKV files into smaller AVI files, MOV files, WMV files. Overall, Pavtube Video Converter is simple, basic video compression app that has a very unlimited functionality.
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