The swiss army knife of lossless video/audio editing
LosslessCut version in the App Stores is often a few versions behind the latest GitHub version, because I want to be sure that the new versions work perfectly before releasing in the App Stores. The GitHub version will contain new, untested features and may contain some bugs (even in existing functionality). I consider the newest GitHub versions to be a public “beta” test. Then, once I’m sure that the new version works well, I will release it in the App Stores as well to give a frictionless as possible experience for customers.
They have exactly the same in-app features, except for a few platform limitations: Apple doesn’t allow opening VOB files with App Store apps. Apple App Store apps run in a sandbox, and therefore need to prompt for output directory before allowing writing files.
Here’s a little primer about video and audio formats for those not familiar. A common mistake when dealing with audio and video files, is to confuse formats, codecs, and file names. In short: A file’s media format is a container that holds one or more codecs (audio/video/subtitle) inside of it. For example .mov is a container format, and H265/HEVC is a codec. Some formats support some particular codecs inside of them, while others support other codecs. The most common formats are arguably Matroska (often .mkv) and MP4/MOV (often .mp4/.mov) as well as their derivatives. Example: If you have a file named My video.mp4, this file most likely (but not necessarily) has the format MP4. Note that the extension of a file (in this case .mp4) doesn’t really mean anything, and the file could in reality for example have the MOV format, or the extension could be .txt. Inside My video.mp4 there are multiple tracks/streams, each with their own codec. In this example, let’s say that it contains one H264 track and one AAC track. In LosslessCut you can view and add/delete/modify these tracks.
Remuxing: If you change the output format in LosslessCut and export a file, you are remuxing the tracks/codecs into a different container format. When you do this, the operation is in theory lossless, meaning you will not lose any codec data and the different tracks will remain exactly the same, even though the format is now different (but some format metadata might get lost due to incompatibilities between container formats). There are limitations: Some popular codecs like VP8 or VP9 are not supported in popular formats like MP4, and some popular formats like Matroska (.mkv) are not natively supported in popular video players like iPhone or QuickTime.
Here is a great introduction to audio/video: howvideo.works.
If the video exports successfully without any error from LosslessCut, but it does not look as expected when playing back, please try this:
Keyframe cut vs Normal cut (do not use Smart Cut if you have any problem)matroska and mov support a lot of codecs.)Each segment’s start cut time normally (but not always) will be “rounded” to the nearest previous keyframe. This means that you often have to move the start cut time to few frames after the desired keyframe.
Keyframe cut vs Normal cut. Most common video files need Keyframe cut, but you may need to try both. ffmpeg also has documentation about these two seek/cut modes. In ffmpeg, Keyframe cut corresponds to -ss before -i and Normal cut is -ss after -i.avoid_negative_ts (in export options).For some files, when you place segment start cutpoints at keyframes, and you export, it will instead cut from the keyframe before the keyframe that you wanted. This is because with some videos, ffmpeg struggles to find the nearest previous keyframe, see #1216. To workaround this, you can try to shift your segments’ start-cutpoints forward by a few frames, so that ffmpeg correctly cuts from the previous keyframe. You can also enable the Export Option “Shift all start times” by +1, +2, +3 frames or so.
00:00:00.200 (or a larger value if it doesn’t help)This will effectively shift all start times of segments by 6 frames (6/30=0.2 for 30fps video).
If you cut a file, but the duration of the exported file is the same as input file’s duration, try to disable all tracks except for the video track and see if that helps. Sometimes a file contains some tracks that LosslessCut is unable to cut. It will then leave them as is, while cutting the other tracks. This may lead to incorrect output duration. Try also changing avoid_negative_ts (in export options).
If you are trying to cut a FLAC file but your output has the same duration as input, you might have run into this ffmpeg limitation.
This can happen when trying to merge files that are not compatible. Make sure they have the exact same codec parameters before merging. If you are sure they are the same, you can try to first running each of the files separately through LosslessCut before merging the outputs:
mp4 is known to fix certain issues like Non-monotonous DTS in output streamDoing this first might “clean up” certain parameters in the files, to make them more compatible for merging. If this doesn’t work, you can also try to change avoid_negative_ts (in export options). Also try to disable most tracks (see above).
Smart cut is experimental, so don’t expect too much. But if you’re having problems, check out this issue. If Smart Cut gives you repeated (duplicate) segments, you can try to enable the Export Option “Shift all start times”.
Some MP4 files ffmpeg is not able to export as MP4 and therefore needs to use MOV instead. Unfortunately I don’t know any way to fix this.
If the output file name has special characters that get replaced by underscore (_), try to turn off “Sanitize” in the “Output file names” editor in the “Export options” dialog. Note that this will cause special characters like / to be preserved. Some characters are not supported in some operating systems, so be careful. using / or \ can be used to create a folder structure from your segments when exported.
FATAL:setuid_sandbox_host.cc(157)] The SUID sandbox helper binary was found, but is not configured correctly. Rather than run without sandboxing I'm aborting now., try to run it as ./lossless-cut --no-sandbox. See #258--disable-gpu - See 781..exe/.zip downloads go? I decided to stop distributing exe and instead just 7zip, due to the problems that the exe download was causing and the large size of zips.Some formats or codecs are not natively supported, so they will play back with a lower quality. You may convert these files to a supported codec from the File menu, see #88.
MPEG TS (.mts/.ts) files have a tendency to be a bit problematic. It may help to first remux them to another format like MP4/MKV. Then you can open the MP4/MKV file an work on that. Also disable non-needed tracks. In LosslessCut you can remux files by simply opening them, select a different output format, and export without editing the timeline (segments).
EXIF/metadata can be preserved (see Export Options dialog), but it doesn’t always output compliant files, so use it carefully. Alternatively you can use exiftool after exporting with LosslessCut to transfer metadata, for example:
exiftool -tagsFromFile original-source-file.mp4 -all:all -overwrite_original exported-from-losslesscut.mp4
More info #1027
When exporting, LosslessCut may be unable to process certain proprietary tracks. For example tmcd, fdsc and gpmd added by GoPro. These can however be losslessly exported to separate files if you want to keep this data for later.
By default, only a single running instance of LosslessCut is allowed. If you start a new LosslessCut instance from the command line, it will instead pass the list of files onto the already running instance. You can override this behavior inside settings Note that this is (experimental), because Electron doesn’t seem to support this. More info #1641
A video’s rotation is just metadata stored in its file. A file can only have a single rotation across the whole file, so if you have two video files and you rotate only one file and then concatenate them, there will be only one output rotation.
If any other problem please search for existing issues before you ask a question here on GitHub. You can check the developer tools for any errors or clues. Menu: Tools -> Toggle Developer Tools.
Also you are welcome to hang out on Discord 🤗