Reasonable settings for video compression?

DawMatt

Reasonable settings for video compression?

« on: 03 / May / 2008, 03:41:19 »

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Hi All,

I have an IXUS 860 IS I bought because of its pocketability, and to take video. Unfortunately I'd forgotten (as a former G3 owner) just how much storage Canon videos tend to chew up. My wife has a Pentax Optio that uses DivX codec and takes 55Mb for a 3:24 min video. I took a 1:17 min video the other day and it consumed 144Mb of space despite being at the same resolution!

Has anyone run some tests to determine reasonable video compression settings to use instead of the Canon defaults? I'm not expecting a point-and-shoot to take video camera quality video so the default settings seem to be considerable overkill:

705kbps, 16 bit PCM audio
1909kbps, 30 fps video

Any setting suggestions appreciated.

Thanks,
Matt

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databoy

Re: Reasonable settings for video compression?

« Reply #1 on: 03 / May / 2008, 04:00:29 »

Memory is relatively cheap in Australia; especially on the east coast. You would be better off to use your camera's optimum setting and use a freeware program called Handbake to post process and compress your video.

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vine

124
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Re: Reasonable settings for video compression?

« Reply #2 on: 03 / May / 2008, 04:22:52 »

A problem I found with cheap memory and high bitrates is that the memory card can not be written fast enough, so that recording is aborted after a very short time.

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scharfis_brain

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Re: Reasonable settings for video compression?

« Reply #3 on: 03 / May / 2008, 05:30:37 »

the canon cameras use MJPEG compression.
That means that avery video frame is stored as a single JPEG frame within the AVI file.
This needs a lot of more bitrate (say at least by factor ten!) than some temporal compression like MPEG or DivX.
So just leave the compression settings untouched.
Everthing else wil just introduce blockyness in your videos or waste space.

Of course there are several techniques to partially undo the occuring compressions artifacts if the chosen bitrate was too low. But this isn't worth the time and effort. Memory is just o cheap...

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DawMatt

Re: Reasonable settings for video compression?

« Reply #4 on: 03 / May / 2008, 06:06:08 »

Thanks for the responses.

Memory is relatively cheap, but at that rate I can only store about 15 mins of video on a 2 Gb card so its plausible to chew through a lot of cards in one day. My bigger problem is that its really going to chew through the disk space. Not so bad with a desktop/server where you can easily add new disks (even then it could get expensive keeping this data online) but my main system is a laptop with less than 1 Gb disk free.

My rough calculations indicate a DVD-R would be consumed by about 35 mins of video. This seems relatively "expensive" for storage given this is nowhere near the quality you'd get from a video camera.

scharfis_brain's comments help me understand why the video consumes so much space. It sounds like I'll just have to transcode after I get the data off the camera which is a shame. I'll also have to change my current workflow for processing camera data because my laptop can't afford the disk space that would be required to keep videos online.

Thanks,
Matt

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Jimmy_Kane

11

Re: Reasonable settings for video compression?

« Reply #5 on: 23 / August / 2008, 22:03:04 »

Bump! Because i have SD800 right now, i thought before buying i could set video bitrate and then get 1h on 2Go but the quality is horrible when i lower the bitrate... What can i do? Buy a Pentax? -_- Help

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Jimmy_Kane

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Re: Reasonable settings for video compression?

« Reply #6 on: 24 / August / 2008, 12:14:25 »

Anyone please?!

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whim

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Re: Reasonable settings for video compression?

« Reply #7 on: 24 / August / 2008, 17:23:34 »

@Jimmy_Kane

I would say the posts preceding yours say it all: either you learn to live with ~15 min per 2 Go card,
or - if you really need 1h continuous video - you need to buy another cam. Sorry.

wim

« Last Edit: 24 / August / 2008, 17:29:14 by whim »

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Re: Reasonable settings for video compression?

« Reply #8 on: 24 / August / 2008, 22:08:02 »

Motion picture on these cameras is more of a gimmick, and is really only useful for very short clips. It's really there just to say they have it, like everyone else. If you are really shooting that much video, get a camcorder. You'll undoubtedly be happier with the results.

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Jimmy_Kane

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Re: Reasonable settings for video compression?

« Reply #9 on: 25 / August / 2008, 07:34:43 »

I'm going to buy the Pentax S12 so! 6Hours quality DivX video on 8GB or more...! I'm very disapointed... I thought with the CHDK firmware i could set the quality and get more time, also because i red comment like "at 0.25 bitrate i store 1hour on 2GB and there's no loss of quality" that's why i bought the camera... what a lyier...

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