AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

whoops · 2010-11-10 11:12:30

Hi!

A customer of mine seems to have his mind set on the general awesomeness of the "Advanced Video Codec High Definition". I can't seem to understand why anyone would want to have a multi-track video editor work with that random assortment of specs - at least as long as it's coming from a (relatively) cheap cam...

So my first impression: "The cam costs significantly less than 20000$ and therefore the video quality can't really get noticeable worse if one just converts the video files with ffmpeg to whatever '60 minutes of video per CD' format it sees fits".

Am I wrong / missing the point? Do you have any experience with "Advanced Video Codec High Definition" cams & archlinux / gnu software etc that should concern me?

Thanks!

ChoK · 2010-11-10 13:24:19

AVC-HD is h264 encapsulated in a mpeg2-TS. It used to be a pain to edit because of the stream complexity, I suppose software/hardware has evolved since then.
About the quality, I suppose the cam doesn't have x264 inside, but you will have better luck lurking on cam/photos' website for that.

Last edited by ChoK (2010-11-10 13:24:55)

whoops · 2010-11-10 13:44:45

Thanks!

And sorry that I didn't make that clear: Looking for an "archlinux solution", that's where the video cutting / mixing is supposed to happen.

Just I don't really see "the problem". I'd guess: "There isn't a problem, just do as usual". Don't understand what "the fuss" is about. As I didn't try anything with an AVCHD source yet, I'm not sure though. In some places, they make it sound like the holy grail but I'd rather not dig deeper in those places unless I need to . Maybe one really needs that fancy software some "computer magazines" write about and the insane hardware requirements those have... well, I'm confused. It's about "random cameras for semi-professional uses" at most. How hard can it be to have a half decent (say - core 2 duo 2.something-GHz) archlinux machine work at a decent speed & not loose the "AVCHD awesomeness" as far as there is something to it?

Maybe I don't "believe in AVCHD" . Can I safely ignore it and just replace the word with "random big video file / format" in my head or will that get me on the wrong train?

(Hope someone understands that despite the fact that my english vocabulary isn't really cut out for that stuff -.-")

Gusar · 2010-11-10 14:07:58

Cams indeed do not have x264 in them (wouldn't that me nice though? ), but they record at a high bitrate, so quality should still be good. As for editing... No idea where Linux editors stand. Avidemux, at least the 2.5 version, does not yet have frame-accurate AVC cutting and I have no experience with non-linear editors. It's true AVC is not the easiest to edit, but that's true for any format that's not keyframe-only.

whoops · 2010-11-10 16:20:31

So... does that mean, that usually the cams just encode with one of those "generic-jpeg-intel-codecs" (or don't compress at all) and the client-side software (that isn't used on a linux platform anyway) or something else does the rest? Or what would be a realistic / common scenario?

Also: for someone who didn't pay much attention to "video standards" in the past, just to understand the general principle... which one of the following two is closer to "the truth"?

(a) To ensure high video quality, it needs to be taken care of that in every step between the camera recording the raw video and burning the finished / rendered "movie" onto a portable medium, the software & hardware is capable of working with the advantages of "AVCHD".

or

(b) Someone obviously has been going around putting AVCHD-stickers on random objects and telling people to buy only those. If one just ignores those stickers, everything should be just fine.

And finally: Does anyone have a cam that says its "AVCHD" and used kdenlive or something & other open software to do a DVD of some sort? Was everything in between manageable with a "normal modern desktop pc" (no highend hardware)?

Last edited by whoops (2010-11-10 16:23:24)

Gusar · 2010-11-10 17:34:14

Err, no, AVCHD means the cam encodes directly to AVC. The rest of the post (all of them actually) are very hard to understand. What exactly do you want to do once you have recorded something?

ChoK · 2010-11-11 02:05:23

So... does that mean, that usually the cams just encode with one of those "generic-jpeg-intel-codecs" (or don't compress at all) and the client-side software (that isn't used on a linux platform anyway) or something else does the rest? Or what would be a realistic / common scenario?
Also: for someone who didn't pay much attention to "video standards" in the past, just to understand the general principle... which one of the following two is closer to "the truth"?
(a) To ensure high video quality, it needs to be taken care of that in every step between the camera recording the raw video and burning the finished / rendered "movie" onto a portable medium, the software & hardware is capable of working with the advantages of "AVCHD".
or
(b) Someone obviously has been going around putting AVCHD-stickers on random objects and telling people to buy only those. If one just ignores those stickers, everything should be just fine.
And finally: Does anyone have a cam that says its "AVCHD" and used kdenlive or something & other open software to do a DVD of some sort? Was everything in between manageable with a "normal modern desktop pc" (no highend hardware)?

It seems to me like you are looking for some documentations so go there http://www.vcodex.com/h264overview.html and skip to the section 4 "h264 in practice"

Basically h264 advantage is for the same video quality, your clip takes much less space (or for the same space it will have better quality). But it will need more power to decode/encode.

Even a "low-end" camera like for example the Panasonic Lumix TZ7 (one of the best compact I think) offers 9Mbps, 13Mbps or 17Mbps when you record AVCHD. With those bitrates a "generic-jpeg-intel-codecs" will be okay. (actually the generic-jpeg-intel-codecs on the cam is a dedicated Digital Signal Processing chip aka DSP chip)

proposition (a) everything capable of working with AVC/h264 can work with AVCHD, it's just a marketing name, there is no special features.
Ensuring high quality is another beast, online guides and common sense help: the less you convert (colorspace for example) or reencode, the less information you will lose.

(b) AVCHD just means the cam can record in h264 instead of DV or Motion Jpeg.

For your final point, beyond a bitrate of 3Mbps dual-core Core 2 Duo CPU feels really sluggish when encoding to h264 but they are good enough to encode to dvd/mpeg2 format. I can't say about kdenlive/openshot/cinelerra and other NLE though, but every open source NLE can work with AVC-HD (via gstreamer or ffmpeg).

Like Gusar asked, it would be great if you can tell us your workflow.

whoops · 2010-11-11 09:10:51

Great, thx, that made things a lot clearer already!

As for the workflow: Nothing really special.
1) Capture video(s) with cam
2) cut, maybe add audio track / text / still images etc...
3) render
4) burn to dvd

I'm not really concerned with encoding times if you mean rendering the "finished movie". What bothers me more are small & big delays while I'm actually working with the video editor. Now I guess with a "slow" machine worst that could happen is that I'd have to convert to something (most likely huge when it comes to filesize) with keyframes only between (1) and (2)?

As for loosing quality through conversion: I'd have guessed that what I actually loose (first) if I strip down a bit is mostly noise. Noise is a bitch when it comes to compression... or are "modern cams" that good that all of the "~13Mbps" is actually something that I want to see (not noise)?

I guess best would be, if I got my hands on one or two files such a camera produces to try if everything works myself... couldn't find any for download so far though, but I'll search again later if noone else knows where to get "test files"?

ChoK · 2010-11-11 14:42:03

There is a Creative Common test file to test new encoders, but it's recorded by an industry grade cam which costs more than 50000$ so not exactly comparable.

You're right noise is a bitch but it depends of the camera sensors not the codec. If you want to filter noise, I'd suggest you to look into Avidemux filters like Fluxsmooth or TemporalSoften. And if you want the best quality, fire up avisynth (via wine/avs2yuv or windows) and use FFT3D or FFT3DGPU (excellent noise filtering without losing much details, and very fast since it's GPU shader-assisted but alas windows only)

whoops · 2010-11-13 08:24:27

So...

I found several test files all over the internet and tried editing them on a few "slow" machines with archlinux & different programs...
- A "really really old desktop" (intel something 1.6ghz, single core, 32-bit thing with 1gb ram) sort of managed to do everything I tried. I didn't try much tough - it was terrible. Reminded me on working with a C64 tape drive for some reason.
- with the core 2 duo 1.6ghz, 4gb ram, it was sort of annoying but manageable: previews were about 50% "realtime" at first - .5 seconds pause every .5 seconds. Takes some time getting used to, should be fine for small projects but gets worse as more tracks, effects etc. are added. That makes it more and more difficult to see what you're actually doing... someone who really knows what he's doing should be ok but trying different stuff out is very frustrating.
- the core 2 duo 2.4 did already much better - still no real "realtime preview" while editing but you hardly notice that you're "lagging" after a while - hu man bra in re ally get us ed to th at fa st. I guess for just the occasional "birthday video" and stuff like that there's no need for a faster machine.

"Openshot" was - at least on these slow machines - most "newbie-friendly" by the way.

Arch Linux

#1 2010-11-10 11:12:30

AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#2 2010-11-10 13:24:19

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#3 2010-11-10 13:44:45

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#4 2010-11-10 14:07:58

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#5 2010-11-10 16:20:31

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#6 2010-11-10 17:34:14

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#7 2010-11-11 02:05:23

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#8 2010-11-11 09:10:51

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#9 2010-11-11 14:42:03

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

#10 2010-11-13 08:24:27

Re: AVCHD / "Advanced Video Codec High Definition" & Cheap cams & Linux?

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