156958 Views Previous 1 2 3 4 5 6 … Next 106 Replies Latest reply: Mar 2, 2015 1:33 AM by muchbetterbig Go to original post Branched to a new discussion.
Thinking about the analogy a little bit further (sorry it takes a bit of time for my brain to get out of neutral)if my word processor does have the capability to edit in shorthand rather than english (and all other word processors on the market could perform this function) than I would want my word processor to do so if it saves me time and hassles.
It is true that editing in AVCHD can be demanding on your computer, but other video programs have been able to make this work on the PC side. I have no issues with native AVCHD editing on my aging Intel Core Duo 3 Ghz using the following programs: Windows Live Movie Maker, Pinnacle Studio, Premiere Elements 9 and PowerDirector 8. That said, I would much rather use iMovie if it allowed native AVCHD editing.
I understand that it is easier for Apple to just convert everything to AIC, but I would rather them invest time in perfecting AVCHD native editing rather than bells and whistles such movie trailers - but that is just my opinion.
AVCHD uses group of pictures compression. In layman's terms, it makes one full frame about every 24 to 30 frames, or about once a second. The full frame contains all 1920x1080 pixels, if you are shooting 1080P, which is the simplest case. (It is not quite that simple - it contains red green and blue color info for each pixel) - but I am simplifying things to try to explain - (but not as simple as the word processing analogy!)
But there are about 30 frames in every second. So what do the other frames contain? They contain information of several types: what has changed since the last frame, the direction of motion, what is moving and what is staying still, that kind of thing. This enables a high degree of compression - as much as 10 to 1. It cannot be 30 to one, because these partial frames take up some space, just not as much space as a full frame. Your camcorder has a single purpose chip that makes this very fast. So AVCHD essentially trades off file size for processing capacity.
Then consider the architecture of iMovie 11.
In the old days, say iMovie 5 or 6, editing was very slow, because every time you you added an effect, a transition, music, etc, you had to wait for iMovie to render that specific clip.
iMovie 8,9, and 11 has a very different architecture, which lends itself to the demands of high definition footage stored on hard drive (rather than tape). It also lends itself to editing very rapidly, with no waiting for rendering. (until the end). It does this by storing all video in Events, which can by accessed by multiple projects. (In iMovie 6, if you wanted to use footage in 3 projects, you had to store it in all three projects, thus tripling the storage space needed.)
So what does a Project do? In iMovie 8,9, and 11, a Project is a hexadecimal text file which contains the paths (and in and out points) to clips which are stored in Events. This text file also contains information about the type and content of titles, the location of photos and music used, the location and length of transition, information on color correction, information on stabilization, fast or slow motion, and several other things. Editing is very fast because there is no rendering involved as you add an effect or transition or music or title. You can see it immediately.
However, when you finish your project, you must render your project using the SHARE menu. The rendering takes place in a single pass. It goes through the text file and resolves all these paths, titles, music references, transitions, color corrections, etc. and creates a finished movie. So there is a need for a very fast processor managing a large number of threads that all have to come together, and a lot of memory.
This assumes that all the frames in the Event are full frames. If you have to do all the above in one pass AND resolve all the partial frames on the fly, you create a huge load on the processor and require even more memory.
For example, the processor is saying, i need frames 12537 through 14634 at path Movies/iMovie Events/Event A/clip1234.mov and start fading in music and a title starting 10 frames later. If you are editing AVCHD, the processor must say I need you to change 12537 through 14634 into full frames and then resolve all the iMovie edits.
Or for another example, take fast motion. You may be doubling the speed by using every other frame, but you cannot simply go out and get every other frame. You have to change the partial frames on the fly to full frames, and then go back and select every other frame.
THis can be done, but it would typically be done in pro apps where rendering is done on smaller units of work than an entire movie.
This is also why iMovie is best for shorter consumer videos. If you are making a feature length movie, you don't want to have to wait until all the editing is done to render your movie. You want to render as you go (but you decide when), and have a work product that is cumulative over the months that you create the feature film.
Soooooo.... It is not that editing AVCHD is impossible. It is just that it doesn't make sense for what iMovie is designed to do, which is to allow amateurs like me to easily make movies on consumer level equipment.
Sorry for the long answer, but you weren't buying my short answer.
Wow! Thanks for you detailed explanation. It was very interesting to read, and greatly increased my knowledge on what is involved.
What I don't understand is how on the PC side there are many video editing options that seem to handle native AVCHD editing without a hitch on my fairly low spec system. What are they doing differently.
I think I read that Premiere Elements 9 and PowerDirector 8 all use a shadow file for the video preview during editing which reduces the system demands but when the project is rendered the actual .mts files are used - does that make sense?
Sony Vegas Studio HD Platinum doesn't use a Shadow File, which probably explains why I have issues with this one.
Other than the native AVCHD editing, what are your thoughts on iMovie not being able to import single .mts files that are stored on a persons system, or the fact that Quicktime can't play .mts files. I would have thought that both of these features are important for amateurs like me to easily store, organise, play, backup and make movies.
Thanks again for your detailed explanation.
... What I don't understand is how on the PC side there are many video editing options that seem to handle native AVCHD editing without a hitch on my fairly low spec system. What are they doing differently.
'AVCHD' is mainly a given file-structure, no codec.
inside the many folders of an AVCHD, you'll find .mts
mts = mpeg-transport .. (=> which indicates, it's not meant for editing.. )
that mpeg is a h264 encoded one - which iM/Quicktime could handle, that is the basic concept of all those mts>>mov converters you'll find on the net, e.g. my site
problem here, as mentioned by appleman1958 - h264 isn't meant for editing, therefor creates a heavy CPU load .. AIC allowed even G4-Macs to edit HDef (HDV) with iMHD vers5
another problem occurs on 'native mpeg'-editing is check-sums. the standard of any mpeg asks for a check-sum for each GOP. manipulating (=editing) inside a GOP could create a 'wrong' checksum. you can ignore that, hoping the player-software will 'hop' over that wrong block of data.
but it could cause 'jumps', artifacts, a full halt of that a movie-file => YOU don't want that, Apple either. So, Apple tries to be close as possible to fulfill Standards, to create a flawless user-experience.
a .mts from within a AVCHD-structure (Cam or Archive file) is guaranteed to be processed.
but there many other .mts out in the wild:
digital TV-broadcast is done with .mts - in many 'flavors' - do want to read (and understand!) a mile-long advice, WHICH mts is supported by a software,
*the price for convenience is limitations.*
if you're in need of 'native AVCHD'-editing, MacOS is the wrong tool - no problem.
Wether AIC anyhow and the conversion of mts to AIC is 'best' should be discussed by the very few compressions-pro, who have a profound knowledge on this issue - so, not me, I'm a hobbyist, I like the convenience, I accept the 'limitations' which aren't for me, because my workflow isn't limited nor does any quality-loss occur.
Hi Karsten Schlüter,
Thanks for your response, this is all well beyond my level of technical knowledge. I guess the bottom line for me is that on the PC side I have had no problem with editing my .mts files natively using a number of different programs and I get excellent results when I export my files (i.e. no noticeable degradation from the original files).
I am sure that there must be some valid arguments for why there is no AVCHD editing within iMovie but from my perspective the PC provides a better option.
Apart from the native editing issue, can you provide an explanation as to why it isn't possible to import single .mts files into iMovie after they have been copied from the camera onto the computer (apart from using the Archiving feature) and no one has explained why .mts files can't even be played without a third party media player.
... can you provide an explanation as to why it isn't possible to import single .mts files into iMovie after they have been copied from the camera onto the computer (apart from using the Archiving feature)
read the paragraph above the 'bolded'-line ... too many different mts-flavours out there; the AVCHD-structure guarantees the ONE, iM's converters supports.
(aside one point, I didn't mention: the many additional Library features of iM are based upon meta-data stored in some files inside the AVCHD-structure, but outside the mts)
.. and no one has explained why .mts files can't even be played without a third party media player.
the Motion Pictures Expert Group (=MPEG) is very strict when it comes to its incomes .. LOL.
for playback of 'raw' mp2, you have to purchase the mp2-plyback-component from apple.com as an extra too... although the DVDplayer.app and iM handle mp2 ... -
Thanks for pointing out that section (this stuff is over my head) but isn't it correct that the .mts files from the major camcorder manufacturers have a consistent 'flavor'. I wouldn't expect that iMovie would support all exotic flavors of .mts but a good start would be standard type used by most camcorder manufactures. This approach seems to work well for all other video editing software. I can't help but think that this sounds like a bit of an excuse.
I would be pretty upset with Apple if licencing fees are the reason for not being able to play .mts files in Quicktime. Given that Apple provide a premium product at a premium cost I think that it is pretty poor that they wouldn't cover this cost when even Microsoft does so.
@Karsten Schlüter & AppleMan1958
First thank you for the explanation on this subject.
On some level i can understand and agree on what you are saying but i'm not sure i get all the details (after all i'm a normal user when it comes to codecs and video knowledge).
BUT as Casho3 says my problem with iMovie/QT is that many applications can do this just fine. Both on PC and Mac. **** i can download a codecpack (k-lite) for free and play them on PC (legally i think).
And why it is not possible to import single .mts files from a local disc is just unacceptable.
Casho3 said it so nice so i repeat it:
"I would be pretty upset with Apple if licencing fees are the reason for not being able to play .mts files in Quicktime. Given that Apple provide a premium product at a premium cost I think that it is pretty poor that they wouldn't cover this cost when even Microsoft does so."
I understand that there might be many flavors on .mts but as Casho3 pointed out they could start with the big brands like Sony/Panassonic and others. This is what voltaichd does so why cant Apple do the same? As i mentioned its not like this is something new, most camcorders has used this format for a while now.
The reason to edit native AVCHD is to maximize output quality due to lossy codecs and generational losses.
It appears that some users would have preferred better quality over movie trailers, but most general use consumers probably are just happy to output any movie with titles, transitions, color correction, pip, etc. Higher output quality probably is not that much of a concern compared to ease of use and speed at this consumer level.
However if mac did incorporate this, and did it well, then some users would be very happy.
I recently purchased a Panasonic HDC-TM700...great camcorder! It records in AVCHD. I've been doing some reading on the internet and eventually got to this thread. Like many here, I think it would be nice to edit the AVCHD files natively. The AIC files iMovie 11 produces on import are HUGE. The untouched .mts files from the camcorder are considerably smaller.
What I've done:
1. Downloaded the trial of ClipWrap, mentioned above. I ran some .mts files through it and it does what it says, but the resulting .mov files get transcoded to AIC by iMovie, so I'm no farther up the road.
2. Followed the tutorial on Karsten Schluter's site that uses "Alan's Automator" rewrap script. The resulting .mov file DOES NOT get transcoded by iMovie into AIC. But it seems like doing anything with the clip puts a heavy load on the CPU--shortly you hear the fans revving up.
One observation is that ClipWrap takes the framerate down to 30, whereas Alan's Automator script retains the 60 fps that the video was shot in.
So it seems like I have a choice of small file size/heavy CPU load or huge files with lighter CPU load.
Does anyone know if lowering the framerate to 30 would help out a lot with the CPU load, and if so, how does one do it?
I was interested to note that when you used ClipWrap the .mov file got transcoded to AIC.
That hasn't been my experience. When you imported the .move file did you happen to have Optimize selected? If you did, then it will get transcoded. You should try deselecting this.
If I recall correctly, when I tested ClipWrap, I actually created a new event folder and copied the .mov file into that folder. When I then opened iMovie the event folder appeared and there was no transcoding.
Casho3: no, I didn't have Optimize selected...
I didn't try adding the clip in the Finder as you suggested...I thought I heard somewhere that bad things can happen to iMovie and your files when you do this...but maybe this was in earlier version and nowadays it's not a problem...
Thanks for the input.
Edit: I did as you suggested and added a new event in the Finder and copied the Clipwrapped file there. It did NOT get transcoded, just as you said. I wonder why it doesn't get transcoded when adding it this way, but it DOES get transcoded to AIC when doing an import through iMovie?