avi format

[dmz]

Yes I have googled this but cant get a simple explanation.
The question is based on quality and the thing called lossy and non-lossy.
From what I understand, if you want to do multiple edits then a non-lossy format is better than a lossy one.
So for photos its better, say, to keep working on a tiff file rather than a jpg file.
For sound its better working on a wav file rather than an mp3 file.
Until recently I though that the avi "format" that came in from my mini-dv tape camcorder was non-lossy and that rendering it to mpeg2 made it lossy.
It now appears that avi is not a format but a container. This is the bit I dont understand. Is my captured avi file from my mini-dv camcorder lossy or not and what format is it exactly?

Thanks

David

[Ken Berry]

Well, at least you understand the concept of lossy and non-lossy; as well as the general idea of wrapper or container formats, like .avi. The truth is that there are over 800 different video formats that call themselves .avi. Some are the original totally non-lossy, and asbolutely huge, uncompressed at all 'avi' format ... but those run at about 65GB for an hour of video. Simply huge. At the far, opposite end of the avi spectrum, you get the highly compressed formats like DivX or XVid, which are in fact mpeg-4 but call themselves avi nonetheless.

Back towards the other end of the spectrum, you have DV/AVI which runs to about 13 GB per hour of video. So since it is not anywhere near as big as uncompressed AVI, it is still compressed (and thus, technically, lossy) but nowhere near as compressed or lossy as DivX or XVid or a wide variety of other AVI formats. Moreover, the mathematics of DV/AVI are such that, while technically lossy, you simply cannot notice the loss after several renders of the video -- in fact quite a few renders. It is moreover easy to edit, and easier to render to other formats. So yes, your format is lossy, but you simply have no reason to worry about that. And it is still the best and easiest format in which to edit SD video...

Complicating matters, though, is the fact that you cannot make a silk purse from a sow's ear. So if you start with uncompressed AVI or DV/AVI, you are fine. But if you start with a more compressed format, such as standard definition, DVD compatible mpeg-2, there is simply no point in converting it upwards to DV since it is far more compressed to start off with. You cannot improve the original quality, and each render will degrade it by one order or quality. So if you have captured video as mpeg-2, it is best to keep it that way, edit it and render it again in that format (using SmartRender where possible) and you will end up -- depending on the original quality -- with around the same visible quality on screen as though you had captured in DV/AVI format, edited it in that format, but then rendered it out to mpeg-2...

[MikeA]

A wonderfully complete response. Yet I am still unsure. I am pretty ignorant about formats, but I have wondered similarly about the advantages of DV/AVI and MPEG. With my old SD camcorder I could capture as AVI or MPEG2. Now, it seemed that if I was making a DVD, which I understand is basically MPEG2, then there was no point in capturing in AVI. That is, the extra quality in AVI was lost when the DVD was made. Instead, it seemed, for space considerations, to use the MPEG capture, which would go straight into the DVD format as is, and would not be degraded. In doing this, there is only one render, and so the issue of multiple renders does not occur. Was this a wrong assumption? Should one use DV/AVI to make a DVD movie if the clips are to be used straight from the capture? Or is MPEG fine?

[sjj1805]

Please view:

Suggested work flow by SJJ1805 for Video Creation

[Black Lab]

As I'm sure Steve's link explains, DVD IS MPEG-2. If your cam can capture either as DV-AVI or MPEG-2, I would capture as MPEG-2 as long as only minimal editing (cutting/trimming) would be involved before burning to a DVD. On the other hand, if I was going to be editing heavily (adding effects, transitions, etc.) I would first capture to DV-AVI because the editing would not affect the quality. Then I would render to a DVD complaint MPEG-2 file to burn to DVD.

[dmz]

Thanks for a great description.
My captures from my mini-dv camcorder are about 12-13gb per hour which I assume is an official format called "dv/avi". In my case dv1 (as i get the option for dv2 but everyone says that is garbage).
Another aspect to this discussion is one I had in another thread.
I was looking to buy a new camcorder, but in the modern technology there are no mini-dv formats. Id prefer a hard drive, however it appears that all modern good quality camcorders that offer hard drives can only be captured in mpeg format, not dv/avi format - therefore less quality.
Maybe a similar analogy is that I have a old still camera that can capture "raw" but all modern cameras can only capture jpeg. I therefore dropped the idea of buying a new camcorder because the capture quality cannot be anywhere as good as my old mini-dv camcorder. Have I made some horrible assumptions or analogies here?

[Ron P.]

Look at Jeff's (Black Lab) signature block. He lists the Canon XH-A1S, which is a mini-DV, though it records Hi-Def as well. I've been racking my brain trying to figure out how to afford one of those. Mini-DV is still around, however mainly in a pro-sumer flavor, not consumer, which translates into pricey...

[Black Lab]

Ron is right. There a fewer and fewer mini-dv cams being made. In this world of instant gratification people don't want to capture their tapes in real time, though dv-avi is a superior format as far as quality and ease of editing goes.

When shopping for a new cam I had to decide whether to spend the money on a new computer that could handle AVCHD files, or spend the money on XH-A1 that I could still use with my current pc. I decided on the Canon for a few reasons. One, AVCHD can still be troublesome, even with a powerful pc. Two, capturing in real time isn't an issue for me because most of my videos are sports highlights. I, therefore, am scanning thru the footage to pick out the highlights, whether it's during the capture process or after it is already captured. And third, the rock-solid dv-avi format.

However, I would not "put down" the MPEG-2 format. Quality wise it's very good. Where you run into quality problems is when you edit it heavily or re-render it several times. SmartRender technology does help because it only renders the parts that have been edited.

So my point of all this is, you have to shop around and decide how your editing style will complement the cam and its format. There is no one-size-fits-all model. Sacrifices and compromises will have to be made.

[dmz]

One always assumes that the technology is on the inevitable march forward. It appears here that that is not the case. So I still ask myself do I hang on to my ancient but superior camcorder?
Am I really in the the same league as those who shout the benefits of vinyl or processed film? I think not.
However I do invite a fair comparison. My old dv/avi is the best - no doubt. But lets say that I only ever download my video and processed and rendered it once - including maybe multiple filters and added text - but only one render to mpeg2 from dv\avi. Would anyone here say with authority that if one render is all I do from dv\avi to mpeg2 then I would not notice any qualitative difference if I bought a new fangled camcorder and only rendered its downloaded (inferior?) mpeg once?

Thanks

David

[Black Lab]

You could re-render 100 times and you might not see any quality difference. As they say, "tis in the eye of the beholder".

To be honest, I think you are over-thinking this whole thing. If you are happy with your current cam and happy with what it produces, then stay with it until it finally dies. (That was my sole reason for purchasing my Canon.) As everyone agrees, DV-AVI is the rock when it comes to editing, and the quality, for SD, is superior. If you really want to upgrade, say for HD, then as I stated earlier, you will have to make some sacrifices/tough choices. And those are choices only you can make.

[Ken Berry]

When moving into the high def world, I opted to go for HDV, mostly because it used the tried and true mini DV tape technology and could at a pinch film in SD DV/AVI (or download in that format), as well as in the high def mpeg-2 HDV format.

The latter is in any case superb in terms of quality (though that of course will also always depend on the person holding the camera!! ) And there are quite a few professional videographers who are not part of the vinyl or processed film variety who still pref HDV technology. I made the switch about 3 years ago and my now "ancient" Canon HV-20 is still more than sufficient for me. I could happily edit its output and author on my old P4... Not so with AVCHD. I acknowledge the technological, time-saving and size benefits of AVCHD cameras, but can see no difference in the final quality of the video to distinguish it from HDV... But boy, with the problems caused by AVCHD and the editing software for it, am I glad I opted for HDV!!

Moreover, I regularly convert mpeg-2 HDV to HDV more than once, or even HDV to AVCHD or Blu-Ray, and have yet to notice with the naked eye any visible deterioration in quality. It might be there if you ran scientific tests, but I suspect that even with two or three re-renders, the degree of degradation would be minimal. And of top of that, you may be aware that I regularly advise users of HD video -- whether AVCHD or HDV -- not to use SmartRender with their projects since this usually leads to problems and artifacts. But I always add the rider to this that those re-conversions should use the same properties -- including bitrate -- as the original video.