Remuxing is the process of transferring the video and audio streams from one container file to another container without any alteration to the streams’ quality. The video and audio in the new container will be identical to that in the original file, but in a different container format.
The main difference between a remux and a re-encode is that a remux only changes the container format, while a re-encode compresses the video and audio streams, which can result in a loss of quality.
Remuxing allows for a smaller file size without sacrificing quality, making it ideal for archiving or distributing large video files.
A container file, also known as a wrapper or a file format, is a type of metadata that contains various types of data, like video, audio, and subtitles tracks, that are encoded with a codec.
The most common container formats are MP4, MKV, AVI, and MOV, each of them can contain different codecs, but remuxing will extract the stream and put it into a new container without changing anything else.
The process of remuxing is relatively simple. First, the video and audio streams are extracted from the original container using a tool such as FFmpeg. Then, those streams are placed into a new container using the same tool or a similar one.
The resulting file will have the same video and audio quality as the original, but it will be in a different container format, depending on user preference or compatibility requirements.
Advantages of Remuxing
There are several advantages to remuxing a video file, some of the most notable include:
Smaller File Size
Remuxing can result in a smaller file size for a few reasons.
Remuxing can lead to a reduction in file size as only the main video and one of the original soundtracks are preserved in their original form, while all other data, such as additional audio tracks, subtitles, or chapters, can be removed.
Additionally, the new container format might be more efficient at storing the video and audio data, further reducing the file size. This smaller file size can be especially useful for archiving large video files or for distributing them over the internet, as it takes up less storage space and can be sent or downloaded faster.
Another benefit of having a smaller file size is that it can be more manageable for the user, it takes less time for processing and copying, it is easier to backup, and it can be more compatible with devices that have limited storage capacity, such as smartphones, tablets, or older media players.
Furthermore, the smaller file size can also make it more efficient to stream the video over the internet, as it requires less bandwidth to play.
While remuxing can lead to a smaller file size, it will not always be the case, particularly when dealing with high-resolution video formats like 4K or 8K.
In these cases, the video streams are already compressed to a point where further compression will not result in significant changes in size. In those cases, it is still beneficial to remux the file, but the size reduction will not be as significant.
Faster Processing Time
Remuxing is generally a faster process than re-encoding because it only involves changing the container format. This is because re-encoding involves compressing and decompressing the video and audio streams which takes longer to process than just changing the container format.
When working with large video files, re-encoding can take several hours, even on high-performance computers.
In contrast, remuxing can take only a fraction of that time, as the video and audio streams do not need to be compressed or decompressed. This can be especially useful for those who need to process multiple large video files, as it can save a lot of time in the long run.
While remuxing is generally faster than re-encoding, the actual time it takes will depend on several factors, such as the size of the video file, the performance of the computer, and the efficiency of the tool being used to remux the file.
Preservation of Original Video and Audio Quality
Remuxing preserves the original video and audio quality because it doesn’t involve any compression or re-encoding. This means that the final file will be of the same quality as the original, providing a true 1:1 copy of the original stream without losing data.
Compatibility With a Wider Range of Devices
Remuxing a video file into a more widely supported container format can increase its compatibility with a wider range of devices and media players. This is because different devices and media players have varying levels of support for different container formats.
For example, some devices and media players may not support the MKV container format, but they do support the MP4 format.
In this case, remuxing an MKV file into an MP4 file would make it more compatible with those devices and media players.
It’s worth noting that different codecs are used within the container format, so even if the container format is supported, the codec used in the video and audio streams may not be supported.
In those cases, you may need to re-encode the file to a supported codec, which would compromise the quality of the video and audio.
Additionally, some devices may not support certain features of certain container formats, such as support for multiple audio tracks or subtitles.
Remuxing a video file into a container format like MKV can provide better organization by allowing for the inclusion of multiple audio and subtitle tracks in the same file. This is because some container formats, such as MKV, have built-in support for multiple audio and subtitle tracks.
This means that instead of having multiple files for a video with different audio tracks or subtitles, you can have them all included in a single MKV file.
This can be especially useful for videos that have multiple audio tracks or subtitles, such as films or TV shows with different languages.
Having multiple audio and subtitle tracks in the same file can make it more convenient for users to switch between them and can also save storage space by avoiding the need to have multiple files.
Additionally, it can improve the overall organization of a media collection by having everything in a single file and making it easier to find and play.
In summary, remuxing can lead to a smaller file size by stripping unneeded data and changing it to a more efficient container format, which can be useful for archiving, distributing over the internet, and for devices with limited storage capacity.
While the file size reduction might not be significant for every case, particularly with high-resolution video formats, the benefits of remuxing still hold true.