It's likely that you have downloaded some great quality movies in MP4 format that are with subtitles in a foreign language, to better follow the movies when viewing them on your computer with VLC or other media players, you may come the needs to add external subtitles to it. However, as the MP4 files are already in excellent quality, you may unwilling to spending long hours to re-encode the video to another format when inserting external subtitles. Is there any software that will just pass through the video as it is and add the subtitles as soft subtitles, so that the whole process can be completed in minutes instead of hours.
Add subtitles to MP4 video without re-encoding
Before going any further, you will first need to download external subtitles for MP4 video from the Internet. You can download them from: moviesubtitles.org, opensubtitles.org or mysubtitles.com. To find suitable subtitles for your movies, please search with "movie tilte" + "your preferred language" + "subtitle" on the above listed websites.
After you have got the suitable external subtitles, the next important step is inserting the subtitle into the MP4 video. If you don't want to lose any file quality, you are highly recommended to complete this subtitle adding job with Pavtube Video Converter (best video converter review), which enables you to output the same file format, profile settings including video codec, bit rate, frame rate, bit rate and audio codec, bit rate, sample rate and channels as the original file format during the subtitle adding process so you that you won't suffer any quality lossage.
Besides adding subtitles to MP4 video, you can also use the program to trim mp4 video length to remove unwanted parts or segments, split large mp4 video into small parts or segments, merge separate MP4 video into one, crop MP4 to remove black bars or unwanted area, replace/remove audio in MP4 video, adding video/image/transparent text watermark to MP4 video or apply special rendering effect to MP4 video, etc.
For Mac users, please turn to download Pavtube Video Converter for Mac to insert external subtitles to MP4 video on Mac OS X El Capitan or macOS Sierra.
Step by Step to Add Subtitles to MP4 Video Without Video/Audio Re-encoding
Step 1: Import MP4 video without subtitles.
Run the program, on the main interface, click "File" > "Add Video/Audio" to import MP4 file that you want to add subtitle to. Or simply drag and drop the file into the software.
Step 2: Choose output file format.
To avoid any quality lossage, just choos the same file format as the original MP4 file.
Then click "Settings" to open "Profile Settings" window to adjust the output file video codec, bit rate, frame rate, bit rate and audio codec, bit rate, sample rate and channels the same as original MP4 file.
Step 3: Add external subtitles to MP4 video.
Select an item on the main interface to activate the "Video Editor" function, in the opended video editor window, click the "Subtitle" tab, check the "Enable" box, then click the "Browser" icon to import and add online downloaded SRT/ASS/SSA subtitles to MP4 video.
Step 4: Start the subtitle adding process.
Go back to the main UI and click "Convert" to start inserting SRT/ASS/SSA subtitles to your MP4 videos with no quality loss.