video editing question - howto snip/crop video losslessly

i'm new to editing video and i have a question about encoding if i wanted to crop a sound out of a larger wav, i'd open it in reaper or audacity, snip out the desired part, and render a .wav of the same properties as the beginning. there would be no quality loss, as there would if i had started with an mp3 and rendered out an mp3 of that mp3. how do i do the same with video? i need to end up with mov files. the videos often start in mp4 format, so at some point i convert them. when/how can/should i make lossless edits to these files? i need to use a specific encoder for the movs, and it doesn't show up in REAPER, otherwise i'd just do it there

haven't used reaper for anything but video playback myself but i'd assume it works the same as audio. as long as you don't filter or resize, basically alter, the video in any way other than cuts and as long as you export to the same container and codec, it should remain lossless, giving you a lossless master file. your subject line says 'crop' which i'd think would not be a lossless process unless the image was left at the same size (and possibly position) without resizing, just trimming edges and such. that may be a gray area. i'd then use something like mpeg streamclip to convert to mov. ffmpeg and ffmbc also can do the conversion but can be harder to work with as they are command line tools. mpeg streamclip is built directly on quicktime and is quite user-friendly. the initial export of a lossless master could maybe be bypassed, directly exporting to quicktime from reaper (an assumption on my part based on the fact that reaper uses ffmpeg for video and ffmpeg handles quicktime) but doing it the first way would give you a lossless master which is probably a good thing to have. can anyone confirm my assumptions, here? thanks, BabaG

if you start with mp4 it is as if you start with mp3. unfortunately videos are very big and most consumer cameras work with compressed files. To record in RAW uncompressed video you have to go for a more expensive camera. but at least if you are going to process video try to convert your mp4 or mts or whatever video you have once, to an uncompressed format while you are working with it. And the for the final rendering, you can compress it again. So you would only compress it twice. Once in the original mp4 file and once in the final rendering of the video. But all the internal editing can be done in loseless codecs. Such as UTVIDEO 444 avi, lagarith, Quicktime Loseless format like Animation codec I think. etc quicktime mov, or mp4 or avi are not codecs... they are just containers. It can be loseless or not depending on the internal codec they have. For example, an avi can be loseless if it has an UTVIDEO RGBA444 stream inside it, or can be compressed if it has an XVID video stream inside it.

yes Some video editors have something called smart rendering that can re export that without re-compressing the data. But they are very limited to some professional editing codecs and to just clean cut edits. I don't think REAPER has anything like that because that's advanced and REAPER is not a video editor. I would be surprised if something like that is added to REAPER. If you are exporting to any video format for web like H264 or webm... it always re-encodes it even if it is a clean cut. This is mainly because the internal keyframes for the compression may not coincide with the frame you cut.. and more reasons.. compression is complex.

thanks, heda. i was under the impression that ffmpeg and vlc could do lossless copying and trimming, ffmpeg anyway. could be wrong about this, though. since reaper makes use of ffmpeg i thought it might be a possibility. maybe for the future? good to know the current state of things. i think handbrake, virtualdub, avidemux, and avisynth are other video tools that can do lossless trimming. all are free. thanks again, BabaG

yes. To cut mts files without recompression I sometimes use TSMuxeR

nym... in your case if your render from REAPER is the final video you are going to upload to youtube for example, then you are exporting (re-encoding it) only one time. so it's all good. You don't need to use a loseless codec. But if you export a first edit in REAPER and then use that to do some final edits in other video editor then you would use a loseless intermediate codec. try extracting those 10 seconds you need with TSMuxeR to a new file, then you can delete the 2 minute file. Or if TSMuxeR doesn't work, then yes, you can use REAPER to render those 10 seconds to a new file with a loseless codec. Then use that new file in REAPER again for the final edit.

You mean cutting out a part of the mov and then add another mov in the begining? Joyoshare media cutter can do this easily and without quality loss. But you can't convert the format or there will be quality loss.