Using Media Track Mixer, you can extract and/or combine media tracks from multiple input media files. For example, you can combine your .mp4 video file with your .srt subtitle file and save it into a .mkv file, or you can extract .mp3 from a .mp4/.mkv music video, or even convert between .mp4 and .mkv. Best of all, this program keeps the encoding of your media files in tact! Powered by FFMPEG.
You need to have at least .NET 9 runtime installed to build the software. Download the latest runtime here. If you're not sure which one to download, try .NET 9.0 Version 9.0.203
In the project folder, run the below
dotnet publish -p:PublishSingleFile=true -r win-x64 -c Release --self-contained false
When that completes, go to \bin\Release\net<version>-windows\win-x64\publish and you'll find the MediaTrackMixer.exe.
You can also just download the release builds if you don't wish to build manually. The assets release contains the assets used by the software, which is just the ffmpeg executable. If you already have this on your system (or you'd rather get it from elsewhere), you won't need to download this. The main release contains the compiled executable.
If you wish to run the software without installing the required .NET runtime, download the self-contained release.
Media files are often composed of tracks or streams. .mp3 files can only have a single audio track. .mp4 files often have video and audio tracks, but can also contain subtitle tracks and even chapters (Chapters are basically bookmarks that mark segments in the media and give the user the ability to jump between them, provided their media player supports it). .mkv files very often contain video, audio and subtitle tracks, and can also store chapters. Then there are files, like .srt, that are not quite media files on their own, but can be added to media as tracks. Most modern third-party media players allow you to switch between tracks. For example, a .mkv movie might have two audio tracks - one in English and another in Hindi or whatever. English might be the default track, but if you prefer the Hindi dub, you can easily swich to that via your media player. The same is true for subtitles. A movie can have regular English subtitles and also SDH English subtitles with extra descriptive captions for deaf people (personally, I switch to SDH if it's available). Of course, you can completely disable tracks too. If the video comes with subtitles, and you don't want them, you can choose to watch without any subtitle tracks. Same for audio. And as far as I know, media players will not allow you to play more than one track of a type at once, i.e, you can't have 2 subtitle tracks on at the same time.
Now, it just so happens that, thanks to FFMPEG, we can copy tracks from one media file to another. You can copy the audio track from any video file and save it to .mp3. You can remove audio from video, by copying all the tracks except audio to a new media file. You can create your own subtitle files and add them to that short movie you directed. If for some reason, you prefer .mp4 to .mkv, you can copy all the tracks and chapters from that .mkv to a new .mp4 and lose nothing! The possibilities are endless!
Note that, unlike many video editing tools that allow you to add text to video, adding a subtitle track to a media file can be undone. Most editing tools just "burn" the text directly onto the video permanently. The text cannot be separated from the video, and cannot be disabled in a media player. The benefit is that the text will show in any media player and the video editor has more control over the appearance of the text. The downside is that the video watcher has no control over it.
When you open the program, you will be prompted to enter the full paths of input media files from which you wish to extract/combine tracks. Each path should be contained in quotes, and anything outside quotes is discarded. You can drag and drop the files instead of typing them out. Enter the corresponding menu number to use a menu.
- Add inputs: Add more inputs to the ones you've already added.
- Replace inputs: Clear out what you've inputed by replacing them with new ones.
- Remove single input: Remove a single input by specifying the input's zero-based index. Zero-based means the first input has an index of 0, second has an index of 1 e.t.c.
- Remove all inputs: Clear out all the inputs you've added to start afresh.
The last menu, "5. Mix tracks", does what you're here for. You'll need to enter the tracks you want to mix, using one or more of the formats below:
- [InputIndex]:[TrackIndex]..... InputIndex represents the zero-based index of the input media file, and TrackIndex represents the zero-based index of the track contained in that input. Zero-based means the first input has an index of 0, second has an index of 1 e.t.c. To select the first track of the second input, you would use 1:0.
- [InputIndex]:C.... C means that you're selecting the chapters of this input. You can't select individual chapters - it has to be all or none. Use 0:C to select the chapters of the first input.
- [InputIndex]:[TrackLetter(s)]..... TrackLetter represents the letter of the track type, which can be v (video), a (audio), s (subtitles) or c (chapters). Use TrackLetter to select all tracks of that type. For example, if the first input has video track 0:0 and two audio tracks 0:1 and 0:2, you can use 0:a to select both audio tracks. You can also use two or more letters. In the previous example, you can use 0:va instead of typing out "0:0 0:1 0:2". The order of the letters do not matter. 0:avs will select all audio, video and subtitle tracks of the first input.
The tracks you select must be separated by whitespace. You can also omit the colon (:), but you probably shouldn't do that for [InputIndex]:[TrackIndex] if there are 2-digit indices.
The order of the selection matters. If you wish to set a default track in a media file, you can select that track first. For example, if there are 3 subtitle track in your video file and you wish to select the 3rd one as the default, assuming that the subtitle tracks are 2, 3, 4, then your selection should be "0:va 0:4 0:2 0:3". Track 0:4, which is the 3rd subtitle track, will be the default.
After you're done selecting tracks, you will need to enter the path of the output file, including the extension. If you specify a relative path (for example, a path without "C:" on Windows), that path will be relative to the path of the first input. So if you enter "MyVideo.mkv" as the output file, a file named as such will be created in the same folder that contains the input file. Be warned that if the specified output file already exists, it will be overwritten!
The file types that this program officially supports are .mkv, .mp4 and .mp3. But there are no limitations at all to file types, and any media file with tracks may work. Keep in mind that there may be limitations with certain file types - for example, .mp3 files cannot store video or subtitle tracks.