Keyframes in MP4

[yepyep]

I'm trying to edit MP4 videos but the keyframes are not set close enough to the points where I want to cut.

Whats the easiest way to rebuild an MP4 with more keyframes?

[Selur]

Reencode with the tool of you choice (sorry, but no clue which you would consider the easiest) and configure it to encode the video with a shorter GOP size, also if the encoder supports it, you can tell it where to put key frames.

[poisondeathray]

If you're going to re-encode it anyway, you might as well edit in the lossless domain (e.g. any video editor, avisynth, etc...)

or you can use something like solveigmm video splitter or videoredo which support smart rendering (only re-encode the frames within a GOP of the cutsite)

[yepyep]

I mostly use Any Video Converter and Avidemux. I should have mentioned that in the first post

I'll look at the avisynth front ends again for GOP options...

[yepyep]

I suspect free and easy are not going to play well together

[poisondeathray]

I'll look at the avisynth front ends again for GOP options...

GOP becomes irrelevant when you use avisynth - because it frameserves uncompressed video

I suspect free and easy are not going to play well together

I think you're missing the point...

Yes you can set the GOP size in avidemux, but why ?

Wasn't the goal to edit with finer precision ? (Initially you wanted to edit using "copy" video and audio - so there is no re-encoding, processing is fast, no quality loss)

BUT - You have to re-encode anyways to make smaller keyframe intervals (you can't "rederive keyframes" without re-encoding the video) - so it's kind of pointless - you're left with short GOP video

So - If you're going to re-encode anyways you might as well edit it whereever you want and re-encode using "normal" settings and GOP length



Ie. - If you wanted to edit in avidemux, change video to something other than "copy" - you can cut wherever you want and it will re-encode the video

[yepyep]

You're right. Avidemux does have the options I wanted... I never used it to transcode before.
Setting the "video" to MP4 and experimenting with adjusting GOP max / I frame threshold.

[hello_hello]

If you're re-encoding when you edit anyway, maybe consider using MeGUI to do the re-encoding. I suggest MeGUI as after it creates an AVISynth script to re-encode the MP4 you can open the script using MeGUI's AVS (script) Cutter. When the AVS Cutter preview window opens you can use it to set multiple start and end points to the script for encoding. The idea being that rather than edit the MP4 then re-encode the edited version, the cuts you add to the script will effectively do the editing when re-encoding. I find it an easier way to go about it. The cuts can be placed on exact frames so there's no need to worry about having to edit the original MP4 on keyframes etc. As well as straight cutting the AVS Cutter can also add dissolve and fade effects to the cut points.
The AVS Cutter will also create a "clt file" which MeGUI can use for re-encoding the audio. The upshot of which is the audio will be "edited" while re-encoding in exactly the same way the video is "edited" when encoding.

[yepyep]

If you're going to re-encode it anyway, you might as well edit in the lossless domain (e.g. any video editor, avisynth, etc...)

or you can use something like solveigmm video splitter or videoredo which support smart rendering (only re-encode the frames within a GOP of the cutsite)

Solveigmm is working on the AVIs that fail with Avidemux. Avidemux sometimes just crashes or ignores the keyframes, starting or ending wherever it pleases... With Solveigmm, if I split with multiple parts, the start of each part jumps back to the last k-frame, but the ends are right on. So then I open each part individually, chop the beginning, and it does work then. Very strange behavior, probably due to very strange encodings.

[poisondeathray]

Did you have smart rendering enabled ? control=> frame accuracy (smart mode)

[yepyep]

The one I have open now is grayed out, but I'll watch for that...