A .mp4 video splitter that actually works? Recommendation needed.

[Flaps]

Hello,

I have a number of H.264 / .mp4 videos that I need to extract clips from. None of the half dozen "splitter" applications I downloaded, both free and shareware, did the job. Either they didn't work at all, or they screwed up the results (stuttering image, etc. ).

Are there any easy-to-use utilities that do this job particularly well? That would let me choose either a starting and ending times, or starting and ending frames, and simply extract that clip?

If I have to pay I don't mind -- I just don't want to waste anymore time. This should be easy. Thanks.

[neuron2]

If they are all failing, then maybe your source clips are bad. How did you make them or where did you get them?

[Flaps]

If they are all failing, then maybe your source clips are bad. How did you make them or where did you get them?

I thought about that, but I think the clips are fine. They are from two separate sources, each a non-commercial DVD. One a theatrical performance, the other a short-form, low-budget spy flick. I used DVD Decrypter to extract the .vobs into a single file. Then in each case, I loaded the single .vob file into Avidemux, to do a little cropping and re-sizing, outputing as .mp4 at 640 x 360 pixels. Avidemux seemed very stable and solid to me. Cranked right through the process without a glitch.

The resultant video plays back fine in Windows Media Player, Videolan, JW Mediaplayer (on the Web), and Quicktime. There is nothing to suggest that any is wrong with the files. But I suppose it's still possible.

[neuron2]

If you have the source material, why do you need to extract it from the MP4?

If you can post a link to a sample MP4 fragment that you are having trouble with, we will be better able to assist you.

[Flaps]

If you have the source material, why do you need to extract it from the MP4?

If you can post a link to a sample MP4 fragment that you are having trouble with, we will be better able to assist you.

Well, right, I could go back to avidemux, select that segment of interest and re-process it, if that's what you mean. But it took me 4 hours of computer time to process this very long video, so I'd rather just grab segments out of the processed .mp4 if possible. Snip, snip. I'm done. Let me see if I can post something for you. Thanks.

[Flaps]

OK, here's a short clip . . .

http://tinyurl.com/d63xmm (http://tinyurl.com/d63xmm)

Please let me know if you can split this into segments and what tool you used to do it. Thanks.

[nm]

Avidemux 2.4.3 split the file without problems. I selected "copy" for both audio and video and set MP4 to be used as output container, then just selected a segment with the marker buttons and saved to a new file.

[Flaps]

nm,

That's the first thing I tried (with avidemux 2.4.4), but I got an error when I tried to load both the big .mp4 file and the small one I just posted on this forum. (See attached error message.)

When I saw that error message, I first answered "no", and sure enough, avidemux crashed. Then, just now, I answered "yes" and it seemed to work. But what's that statement about loss of frame accuracy? Doesn't sound like a good thing ;-(

What does it mean?

[nm]

Avidemux normally allows frame-accurate edit operations (cutting at any frame and then re-encoding the whole stream), but currently it can't do that with H.264 input. I don't know the details, but this may be related to problems with frame-accuracy in libavcodec that neuron2 has been suffering from in his DGAVCDec tool.

Anyway, Avidemux is simply informing you that it can only seek to keyframes in H.264 files. Alternative tools aren't any better in your case since I don't think that any currently available program can do frame-accurate splitting of H.264 streams (re-encoding only the beginning and the end of the video up to the first and down to the last keyframe). So, cutting at keyframes is your only option that avoids re-encoding the whole video.

[Flaps]

Excellent, thank you. I'm happy to say I followed what you explained. So, it appears that what I should have done, if I wanted to perform surgical splitting, was to do that on the original .vob and spit out each one of those clips as as separate file (maybe an .avi?), then join them together as required. I chose to do it the way I did because someone else needed to view the whole movie on the web to actually decide what segments to extract. In this file, the keyframes are showing up every few seconds. So I'll trim to the nearest keyframe and that will be close enough for this project. Thanks for your help!

Is there a way to control the frequency of the keyframes when saving to the .mp4, or is that an automatic function, dependent on the program material?

[neuron2]

I chose to do it the way I did because someone else needed to view the whole movie on the web Closed for forum rule 6 violation.