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View Full Version : What bit rate is best for "casual" use, eg home video?



D90GH1_eric
10-10-2009, 11:32 PM
I shot a few minutes of a trip to the restaurant at 720/60 (AVCHD). For video quality, I selected "SH" (17MBPs). When I added all the clips together , I found that they are more than 1GB in size. I am thus curious what difference will I see if I select a lower bit rate? At this point, I mostly view my movies in the computer, and have no plans to view it on large TVs. I am a Mac user and the software that I use is iMovie 8.0.4. I am a very experienced still photographers and have no formal training in videography. Thanks.

Ozpeter
10-11-2009, 02:05 AM
The only way to tell is to do some further experiments yourself, as only you can tell what you are satisfied with. But maybe have an eye to the future, and consider whether in a few years' time you'll be satisfied with the reduced quality that you are happy with now.

Ben_B
10-11-2009, 06:12 AM
When editing on a mac AVCHD is always going to end up huge. For casual use try MJPEG mode instead of AVCHD (you change this one above in the menu where you change SH FHD etc, I think) it is 720p/30 and handles high movement better than AVCHD on the GH1, but overall (IMO) the footage does not look as nice (a bit more compressed looking...) but I am pretty sure the file sizes will be much more manageable...just know that this is indeed the casual mode. People on this forum shooting serious film stuff avoid the MJPEG mode because of 30p and the poorer look...but this sounds like it will suit you just fine.

Kerplunk
10-11-2009, 06:47 AM
Ben, you mean editing on a Mac using FCP. Those of us using Premiere enjoy AVCHD editing without the huge file transcode. Right out of the camera and into the timeline - it's sweet. :happy:

D90GH1_eric
10-11-2009, 07:59 AM
The only way to tell is to do some further experiments yourself, as only you can tell what you are satisfied with. But maybe have an eye to the future, and consider whether in a few years' time you'll be satisfied with the reduced quality that you are happy with now.

In theory, what do different bitrates do? Is this an issue of compression? For example, when you save a still images in JPEG, you can select different levels of compression and this largely affect how large you wish to print and how much post-processing one need to do. If you were preparing for something to be shown on Youtube, for example, what would you do?

Ben_B
10-11-2009, 12:11 PM
Shoot with MJPEG mode.



Ben, you mean editing on a Mac using FCP. Those of us using Premiere enjoy AVCHD editing without the huge file transcode. Right out of the camera and into the timeline - it's sweet. :happy:

And then you need to have top of the line hardware (otherwise right out of the camera into the timeline with lots of frame drops and lagginess and crashes while you're editing) and then you're stuck editing in Premiere which I do not like nearly as much as FCP...if I had top of the line hardware transcoding would go really fast, and I'd probably also be able to afford more storage, as it is exceedingly cheap. I can edit my GH1 footage on a two year old mid-range Macbook with no GPU or my 3.5 year old iMac because I transcode my footage to something easy to deal with, ProRes LT...even it is like 700 mb a minute :D

commanderspike
10-11-2009, 12:24 PM
I switched to a Mac mainly because it was better than Windows for video editing. Premiere used to be sh1t slow with HD footage from my FX1. But I believe the latest developments on the PC are quite promising and Premiere has improved a lot. It is also much cheaper to get powerful CPU / GPU combo on a PC than it is on a Mac, especially when it comes to laptop.

But that is no big reason to me, to have to endure the hell of Windows ever again :)

D90GH1_eric
10-11-2009, 01:29 PM
Another question, if I may. I compared the file size after being imported into iMovie, and found that the clips created at 1280/24 (FHD mode) is actually only half the size of those created by 720/60 (SH mode). Why is it?

After seeing the quality of 1280/24 on screen, it is hard to go to MJPEG ...

Barry_Green
10-11-2009, 05:26 PM
In theory, what do different bitrates do? Is this an issue of compression? For example, when you save a still images in JPEG, you can select different levels of compression and this largely affect how large you wish to print and how much post-processing one need to do. If you were preparing for something to be shown on Youtube, for example, what would you do?
Yes, you pretty much have it right. The smaller the bitrate, the smaller the file sizes, and the more compressed it will be. The higher the bitrate, the better quality the file sizes.

Be aware though that the GH1 changes the resolution based on what mode you've set, so FHD = 17 megabits but it's 1920x1080x24fps, whereas SH mode = 17 megabits also, but it's 1280x720x60 fps.

commanderspike
10-11-2009, 07:03 PM
I find that 720p at 60p is the same size as 1080p at 24p on the GH1.

Why is that? More than double the frame rate but lower res I guess can account for it? Is that correct?

Park Edwards
10-11-2009, 07:07 PM
Shoot with MJPEG mode.




And then you need to have top of the line hardware (otherwise right out of the camera into the timeline with lots of frame drops and lagginess and crashes while you're editing) and then you're stuck editing in Premiere which I do not like nearly as much as FCP...if I had top of the line hardware transcoding would go really fast, and I'd probably also be able to afford more storage, as it is exceedingly cheap. I can edit my GH1 footage on a two year old mid-range Macbook with no GPU or my 3.5 year old iMac because I transcode my footage to something easy to deal with, ProRes LT...even it is like 700 mb a minute :D

wouldn't any intermediate codec other than avchd be better for a computer that's not beefed up? you can convert to cineforms codec(not necessarily this codec) like you could apple's pro res and not have a mega machine.

Barry_Green
10-11-2009, 07:25 PM
I find that 720p at 60p is the same size as 1080p at 24p on the GH1.

Why is that? More than double the frame rate but lower res I guess can account for it? Is that correct?
The bitrate is fixed, 17mbps. A 1920x1080 frame is about twice the size as a 1280x720 frame (2.25x actually), but the 720p has 2.5x as many frames per second, so ... yeah, it all ends up about the same.

Ben_B
10-11-2009, 08:01 PM
Yeah, I think of it like pixels per second.


Barry: my hardware seems to handle ProRes just fine..but yes sometimes for a longer project I will transcode to AIC or more recently Pro Res Proxy, edit, relog to ProRes LT, reconnect, media manage, delete the excess...but I've found the extra transcoding time isn't usually worth it.

D90GH1_eric
10-12-2009, 07:38 AM
I find that 720p at 60p is the same size as 1080p at 24p on the GH1.

Why is that? More than double the frame rate but lower res I guess can account for it? Is that correct?

Which software do you use? With the iMovie in Mac, there is no doubt that with the same length of time of recording, the file created by 720/60 is twice the size of that from 1080/24.

1920x1080x24 = 49,766,400
1080x720x60 = 7,776,000

50 million vs 8 million?

BhambuNath
10-12-2009, 08:28 AM
They should be of same size - I record on 8GB card and no matter if I record 1080P or 720P I can record 1 hour of footage in both modes on this 8GB card.

D90GH1_eric
10-12-2009, 09:05 AM
They should be of same size - I record on 8GB card and no matter if I record 1080P or 720P I can record 1 hour of footage in both modes on this 8GB card.

I never checked the size of the file on the memory card. The file size that I refer to is what I get after iMovie converts it to the .MOV files.

Cranky
10-12-2009, 09:25 AM
1920x1080x24 = 49,766,400
1080x720x60 = 7,776,000

50 million vs 8 million?
First of all, 1080x720x60 = 46656000
Second of all, I suppose you meant 1280x720x60 = 55296000

In any case, you are not recording uncompressed.

D90GH1_eric
10-12-2009, 11:33 AM
First of all, 1080x720x60 = 46656000
Second of all, I suppose you meant 1280x720x60 = 55296000

In any case, you are not recording uncompressed.


Woops, you are right, so they should have been 55m vs 50m.