Re-encode selected fragments of mkv

[Freodon]

I have .mkv files with AAC and h264 tracks. I want to re-encode it while omitting a fragment in the middle. What software can do this, while:
- losing as little quality as possible
- having the ability to select more than one fragment (multiple start-end times going into a single file) - that middle fragment omitting is why I can't use Handbrake for this
- it must be frame-accurate

[LMotlow]

Why re-encode? That's a quality hit. For frame-accurate simple edits you need software that can smart-render with frame-accurate cutting. Most software that can do this well aren't smart-rendering and aren't free. I use TMPGEnc Smart Renderer (handles several formats, including MPEG and h264). I'm not familiar with any smart-rendering freebies. Others can advise there.

[Freodon]

I know about smart rendering, but some of those files are poorly encoded and trimming it creates a stutter near the cutting area.

[LMotlow]

That's why you need a smart-rendering editor. Either that, or you have to cut only on GOP limits. Not doing it without smart-rendering causes problems. Like stutter. Not to mention re-encoding. Smart-rendering editors usually have a trial version you can audition.

[Freodon]

MkvCutter is like that - it encodes only near trimmed parts, and yet stutters are created sometimes, even after previously re-encoding the whole file with Handbrake.

[LMotlow]

A sample of one of those AAC/h264 mkv's would answer a lot of questions. If it's encoded with huge GOPs, clean edits will be a hassle.

[poisondeathray]

Not all smart rendering software works necessarily as well as one another. Don't lump them all together. Even the ones that work well, have problems with some source streams, encoding settings and profiles

[LMotlow]

True. A typical sample would help.

[poisondeathray]

If you've already decided you're going to re-encode, or if your streams give all the smart renderers problems, then I would use avisynth trim()

If you use a frame accurate source filter, you are far less likely to get glitches at the join or trim points since everything is done in the uncompressed domain .

For a GUI, you can use megui, it has an avs cutter, or some people prefer to do it in avspmod

[hello_hello]

I agree with poisondeathray. If you're going to re-encode anyway, use Avisynth. I mostly use MeGUI (an Avisynth based GUI). After it's created a script for encoding the video you can open the script with the AVS Cutter under MeGUI's Tools menu. That lets you specify multiple "cuts" frame accurately with a preview. You're actually specifying multiple start and end frames for encoding which the AVS Cutter then adds to the script for you. It'll also save a "cuts file" which can be loaded into MeGUI's audio section so the audio is re-encoded to match.... or the the Audio Cutter under the Tools menu will use the same "cuts file" to cut/splice the audio without re-encoding it. When it's all done you can remux the video and audio with MKVMergeGUI or one of the muxers under MeGUI's Tools menu.

What I also sometimes do is encode the video in sections as individual encodes without the audio (you could probably also encode it in multiple sections with Handbrake). The idea being you divide the video into sections so there'll be a keyframe at the beginning of each section when you want to split it again later. For me, it's the "lazy man's way" of doing it without a need to worry about the audio as such.
After the video sections are encoded you can append them together with MKVMergeGUI, add the original MKV, deselect the original video, then save that as a new MKV containing the encoded video and original audio. Once that's done you can split it again with anything that'll split MKVs..... ie MKVMergeGUI.... and the keyframes will be in the right places, then you can join the split MKVs together again with MKVMergeGUI while leaving out the sections you don't want. That sort of thing.....

It's a good idea to add --stitchable to the x264 commandline so there won't be any issue appending the encoded video (assuming the same settings are used each time). I'm not sure how you'd do that with handbrake, or even if the version of x264 it uses requires it.

Video To Video Converter has a commercial remover under the Tools menu which lets you split with a preview. It'll only cut on keyframes, unless you want to re-encode, but it's pretty easy to use. There's a link to the portable version of Video To Video Converter on the VideoHelp page which you can just download, unzip and run (apparently the "installer" version tries to get you to install toolbars or some sort of adware as well).