Editing program for AVI, MKV video

[rocks911]

I'm looking for a freeware program that can lop off video and not change the format. I need about thirty seconds of video removed from the front end. Simple enough eh?

[Baldrick]

avidemux or solveigmm avi trimmer.

[rocks911]

Thanks for that.

As I've come to love MKV, is there a good program that converts anything into MKV with support for Dolby and/or DTS?

[rocks911]

So maybe I'm slow but I tried the solveigmm avi trimmer and it isnt working for me. I load the movie, set the beginning marker, play the movie for a minute or so (just until the obnoxious text over the movie intro fades) and i set the stop marker. I look for the minus button to be illuminated, as in erase the chosen field, but it's not illuminated. I read the directions and it indicates that after setting the start and finish markers to hit save, which I did but that didnt eliminate the section I needed it to, in fact it wasnt changed at all.

I have a few DL'd vids that have rather annoying text written over the content at the beginning of the vid that I want to erase, simple right?

Maybe it's my W7 64 bit machine, it seems some software just doenst want to work on it.

[jagabo]

I have a few DL'd vids that have rather annoying text written over the content at the beginning of the vid that I want to erase, simple right?

Conceptually it's simple. But the intricacies of video compression make it very difficult. All high compression codecs gain a large part of their compression by not repeating portions of the frame that don't change from frame to frame. The first frame will be a keyframe -- a self contained image, like a JPG image. The second frame will only include the parts of the picture that are different from the first frame. The third frame will only contain parts that are different the second. Etc. Eventually, it will encode another frame as a keyframe (to make random seeks much easier). Then go back to just the changes. (Actually it's much more complicated than this. Frames can reference frames both before and after them, and not just the immediately adjacent frames, and frames aren't necessarily stored in order they are to be viewed) The distance between keyframes can be anywhere from a handful of frames to hundreds.

Say you have a 30 fps video and the first GOP (group of pictures, the distance from one keyframe to the next) is 300 frames long. That means the next keyframe is 10 seconds into the video. Now you want to cut out the first 5 seconds of the video. The editor can't just remove the first 150 frames. Frame 151 needs information frame 150 to reconstruct the entire picture. Frame 150 needs information from frame 149 to reconstruct the picture. Etc. All the way back to the first frame.

So there are basically three types of editors.

1) Keyframe only editors. These are simple editors that only allow cuts on keyframes. They are fast (they never reencode anything, they just copy GOPs from the input to the output) but since you can only cut on keyframes you don't get frame accurate editing.

2) Dumb editors. These give you frame accurate cuts but reencode the entire video. So they are very slow.

3) Smart editors. These give you frame accurate editing but only reencode cut GOPs. Unmodified GOPs are simply copied to the source. This makes then nearly as fast as keyframe only editors. (This assumes only simple cut/paste editing. If you are applying filters all frames have to be decompressed, filtered, then recompressed).

[rocks911]

Thanks for the reply. OK so it's not simple, nothing is these days I guess. I did manage to do what I needed with Avidemux so thanks Baldrick

[edDV]

To add audio to Jagabo's description, a tight audio sync needs to be accurate to a frame or two for good lip sync but subframe (<0.3sec) for explosions or tight effects sounds. Many muxing schemes only sync audio to 10 second GOPs so you can see how cutting inside a GOP can affect audio sync.

In contrast packetized transport streams used for broadcast or media recording anticipate transmission loss so use short GOPs (0.5 sec 12-15 frames typ) and can resync audio even with lost packets or full GOPs.

[rocks911]

I had no idea it was so technical.

But I was wondering is there a good program that converts anything into MKV with support for Dolby and/or DTS?

What do people use to back up blu rays for example?

[jagabo]

MKV is a container -- a box that holds audio and video. You need to specify what codecs you want to use.

You can use mmg or avidemux to remux (take the compressed audio and video out of one container and put it in another) from other containers into MKV. The file size will be about the same because the video and audio aren't changed in any way.

If you want to reduce the file size, or recompress from a codec your player doesn't understand to a codec your player does understand, you can use programs like xvid4psp, ripbot264, megui, handbrake, staxrip, avidemux. None of them handles every possible file but they handle a wide variety of sources.

Specifically for Blu-ray to MKV:
https://www.videohelp.com/tools?toolsearch=&Submit=Search&convert=Blu-ray+to+MKV&s=&ord...y=Name&hits=50