lossless cropping?

[hardy]

Is there a program that does a lossless crop? Instead of choosing the aspect ratio like everything does which only shrinks the picture and degrades the quality. Cropping the video would still be lossless and a smaller file size. I have noticed that DVD Ripper version of DVDFab has that option, not sure if it's lossless but they have the cropping option where you can see and choose the section.

A few of my dvd's are still over 5GB after copying the main movie so I would like to crop a small portion so they will fit on a single layer dvd.

[hech54]

Your terminology is completely bass-ackwards.

[filmboss80]

You're using the word "cropping" in a way that will confuse most people involved in editing. The term usually applies to cutting down and reframing a portion of an image. From your post, I believe you merely want to pull out DVD segments until the file is the proper size to fit on a disc. You could save only the main movie with DVDFab. However, you might do better with longer movies using DVD Shrink in the reauthor mode.

[hardy]

But you understand what I'm saying, not looking to "shrink" the picture, just simply cut out some around the edges like cropping. I didn't know if there was a program out there that could handle that.

[hech54]

Impossible.

[yoda313]

You can cut segments losslessly.

But I think you'd be better off just doing a transcode to single layer.

But in the end your best bet is to simply get a dual layer dvd burner and burn the full original file assuming it was 8gb or less.

[hardy]

Would it be better to cut segments losslessly or just use a program like StaxRip and encode the files to H.264 using x264.

[yoda313]

You can encode to h264 simply enough as long as you don't need it to be in an actual dvd format. That will work also.

[mpalm887]

You can cut segments losslessly.

But I think you'd be better off just doing a transcode to single layer.

But in the end your best bet is to simply get a dual layer dvd burner and burn the full original file assuming it was 8gb or less.

How? You're still saying that you can cut segments as in clips (i.e. from 00:46:21 to 16:56:09) right? Like you can do a lossless cut with DVD shrink in reauthor mode. You aren't suggesting that you can cut off a portion of the frame i.e. letter-boxing bars without re-encoding are you?

[guns1inger]

No. You cannot cut off portions of a frame without re-encoding. If you alter the visual appearance of the frame - brightness, colour, image, size - then you have to re-encode.

Simple editing - splitting/joining - can be done with little or no re-encoding under the right circumstances.

Cropping - removing a portion of the video frame, with or without resizing - always require re-encoding

[jagabo]

And if you're going to reencode the video there's no reason to crop the frame. You can just use a lower bitrate.

[yoda313]

Sorry looks like I wasn't thinking straight on this one. Yes I was thinking about the dvd shrink approach but that would only be after a dvd format is created.

[hardy]

Can you set a target file size without choosing a size ratio? Will it automatically reencode the movie...

[mpalm887]

Can you set a target file size without choosing a size ratio? Will it automatically reencode the movie...

I looked at staxrip and I don't like the UI as much as RipBot264 which is so intuitive and easy.

With RipBot you can set the encoding mode to 2-pass and then set the bitrate. It will tell you the projected file size as soon as you enter the KBPS value, so you can mess around with it until you get the size limit you want and then you're off.

[hardy]

I looked at staxrip and I don't like the UI as much as RipBot264 which is so intuitive and easy.

With RipBot you can set the encoding mode to 2-pass and then set the bitrate. It will tell you the projected file size as soon as you enter the KBPS value, so you can mess around with it until you get the size limit you want and then you're off.

StaxRip also lets you set the encoding mode to 2-pass and then set the bitrate. The 2 programs are pretty similar.

[live]

I don't understand the answer to the post.

I have the same issue:
It is possible for some lossy compression format to have lossless transform, for instance on JPEG it is possible to do certain crop or 90° rotate in a lossless way, viz without re-encoding. See http://jpegclub.org/losslessapps.html

Now, I wish to crop some video file - crop means to me rectangle cut part of unwanted portion of images, viz I filmed with a wide ange and I want to refocus my film.

1/ Is it possible to do it in a lossless way, if the video is in
1.1/ FLV?
1.2/ H.264
1.3/ MPEG2

2/ With which softwares?

Thanks.

[Baldrick]

Not with video.

[live]

>Not with video

OK, then if I want to crop a video, is it better to "crop" and re-encode in the same format or for instance in H.264

Thanks

[Baldrick]

It depends on the source codec and what bitrate you are using. But I would probably use h264 with same or higher bitrate as the source.


Best would be to crop and save as a "lossless" codec like huffyuv, lagarith...but it would be a huge file.

[jagabo]

It is possible for some lossy compression format to have lossless transform, for instance on JPEG it is possible to do certain crop or 90° rotate in a lossless way, viz without re-encoding. See http://jpegclub.org/losslessapps.html

Yes, that's possible because a JPG image is a single entity. The compressed data encodes the entire picture. High compression video codecs start with similar compression techniques but on top of that frames can reference other frames. This makes the job much more difficult.

For example, say a ball was at the very edge of the picture in one frame and at the middle of the picture in the next. The compressed video might recognize the ball is the same and simply say "copy this block of pixels (that contains the ball) from that X,Y coordinate in the last frame to this X',Y' coordinate in this frame." If you crop away the edge of the frame there's no ball in the prior frame anymore. How's the decoder going to know what to put in the middle of the picture? The use of "motion vectors" like this are a large part of video compression. x264 and MPEG2 use it all the time.

Note that FLV is a container that can contain video compressed with a number of codecs including h.264, VP6, and others.

[neomaine]

Now I see where Ally68 was coming from. The assumption (incorrect) was that you could reduce the file size of a video by cropping out pillar/letterboxing like you can reduce the file size of an image by cropping.

Ally68, filesize = bitrate x length(time), and that's it. So to reduce the overall size you need to either cut out segments, like the beginning/ending credits, and/or reduce bitrate until you reach your desired size.

I'm assuming you still need to go from DVD9 to DVD5 and want to get your 5gb+ movie to <4.5gb. Being that close to your desired size, I'd recommend DVDShrink to reauthor stripping out what you don't need and use the shrink option to get it to under 4.5gb.

[live]

>58jagabo
I partly understand your point with the ball and vectors, 'cause I'm still "new" at video, but here is why.

MP3 is lossly and also works with frames.
Now if you take some MP3 VBR(Variable Bit Rate) sound and I frequently work on genuine VBR being 32 to 320 Kb encoding, it is possible to cut + paste(normalize, etc) without re-encoding.
MP3DirectCut is the best soft at it.
Now, when I work on a speach I can remove unwanted parts or paste new ones, but if there gliches/cracks from a microphone for instance, I can't cut it, because it's under the structure of lossless transform (I think about 1/32 of sec but no need to remember). Of course I can remove them but, then it needs re-encoding.

I don't know yet much about the internals of video formats, but I wonder if some lossly video formats would not allow certain lossless transformations.
For H264 at least to the level of a VBSMC http://en.wikipedia.org/wiki/H.264#Features

Indeed, the similarity of a fixed background at which in fore front a play (e.g. football, dancing, theatre, ...).
I would imagine one could "crop" the unwanted background only to focus on the moving parts otherwise one would take a picture !

I haven't found a clear answer on BitRate computation, but it seems logical & intuitive that "cropping" would reduce bitrates as the higher number of pixels on a given scene, the heavier, although might not on a vectorial coding.

Thanks

[guns1inger]

Reducing the resolution, either by cropping or by simple scaling, may reduce the bitrate required to encode a certain scene, or it may mean you get better quality because you are encoding less pixels at the same bitrate. Assuming you can do the re-encoding with no loss, which you cannot do with a lossy codec.

There was some work a while back involving mpeg-2 video and certain basic adjustments without the need to re-encode. However these were, if I remember correctly, limited to basic brightness/contrast/hue adjustments, and nothing ever seemed to come of it.

However comparing mp3 audio compression with mpeg-4 video compression is not comparing apples with apples. The intra-frame and GOP temporal nature of video compression makes ability to make these adjustments far harder than upping the gain in a MP3 track.

[jagabo]

I don't know yet much about the internals of video formats, but I wonder if some lossly video formats would not allow certain lossless transformations.

Of course there are lossy codecs that allow some transformations without decompression and recompression. For example, DV AVI can be brightened or darkened without reencoding (there are tools that do this). Cropping the frame is possible with MJPEG (at least in theory, I don't know of any app that actually does it) and would indeed reduce the overall bitrate rate. Cut/paste editing is possible with inter-frame codecs but only on I frames (and closed GOPs). Etc.

Indeed, the similarity of a fixed background at which in fore front a play (e.g. football, dancing, theatre, ...).
I would imagine one could "crop" the unwanted background only to focus on the moving parts

In theory, if the edges of the frame never change, it would be possible to crop those unchanging edges. But in the real world that never happens. Even a tripod mounted camera moves a little bit, and film bounces when digitized, so motion vectors end up crossing the crops. Even if you had a video that was a candidate for that (say a computer generated animation) you would find it reduces the bitrate very little. All those unchanging parts of the frame aren't included in every compressed frame. High compression codecs just encode the changes between frames for most frames (in essence, the codec says "repeat the last frame, just make these changes...). So unchanging backgrounds contribute very little to the overall bitrate.

In any case, I'm not aware of any program attempts to losslessly crop the frame with any video codec.