Edit after using HB

pixel · Post by **pixel** » Wed Jan 02, 2008 12:01 am

Sorry if this has been discussed before, but I really can't come up with useful keywords to search on for it.

I have been using HB to convert particular chapters of dvd's for my ipod. The high res ipod preset works great. However, there are a few times when I need to trim 5-10 minutes off of a chapter. I have the full version of Quicktime and can use that to edit. However, I then have to export it using Quicktime's export to ipod. It seems like I'm having to go through a convert to ipod process twice.

Is there a better preset to use in HB if I plan on editing it in quicktime afterward? Any suggestions for a better way to go about this would be welcome.

sdm · Post by **sdm** » Wed Jan 02, 2008 2:08 am

You can edit an .mp4 (also known as .m4v) containing AAC audio using the program 'mpeg streamclip'. Do a 'save as' to save your trimmed file as an .mp4. This won't re-encode so its quick. You'll lose chapters though.

-sdm.

[edited for clarity]

pixel · Post by **pixel** » Wed Jan 02, 2008 2:36 am

I can't quite parse your first sentence, but if you're talking about doing a 'save as' in quicktime that's not an option.

The 'save as' in quicktime (after I've trimmed it) only allows me to save it as a .mov, no other options. I have to go to 'export' to get a mp4. It takes quite a while though, so I assume it's re-encoding it.

sdm · Post by **sdm** » Wed Jan 02, 2008 2:41 am

sorry - I've made my previous post more consise.
Hope that helps.

-sdm.

pixel · Post by **pixel** » Wed Jan 02, 2008 6:46 am

Thanks! I'm downloading that app now and will give it a try. From the HB presets, it's still a good idea for me to use the iPod high res preset, right?

sdm · Post by **sdm** » Wed Jan 02, 2008 3:25 pm

I'd say the iPod preset would still be a good choice. My iPod doesn't support video so I can't test.
I should also mention, if your edits aren't on I-frames, I think mpeg streamclip needs to encode a small amount.

--sdm.

pixel · Post by **pixel** » Wed Jan 02, 2008 11:02 pm

sdm wrote: I should also mention, if your edits aren't on I-frames, I think mpeg streamclip needs to encode a small amount.

--sdm.

Does re-encoding result in poorer quality? Maybe it's better if I use the QT or normal HB preset if I plan on editing it and then export for ipod from QT? I'm still unclear on that.

sdm · Post by **sdm** » Wed Jan 02, 2008 11:14 pm

I wouldn't worry about the small amount of re-encoding.

In a very simplified explanation, the video contains key frames (aka I-frames) that are entire frames. Other frames are rendered referencing the key frames.
I think if you edit on a non-keyframe, new keyframes would need to be built on either side of the edit and the ones in-between would need to be re-encoded too.

Have you tried it yet? How does the quality around the edit look?

If I'm not correct here, I admit it. Someone else will surely point it out!

good luck
--sdm.