[MEncoder-users] Compressing the photo camera Canon A610 video to mpeg4 at the best quality.

[Lennart Börjeson]

I have essentially the same experience with a Powershot S2 (and before that 
with a Powershot G1). Mjpeg is not really a "movie compression" format, it is 
only a sequence of individually jpeg-compressed images.

Like you, I've found that it is sometimes very hard to compress the files and 
achieve acceptable picture quality. My theory is that when shooting these 
clips, at least I tend to try to make them short and "interesting", i.e. I'm 
mostly trying to capture some action filled moment when the children are 
doing something clever or funny. That results in a sequence of frames with 
lots of high motion, and when the clips are short there are no "dull 
moments" (as there inevitably are in a full-length feature movie) which the 
codec can use to even out the bitrate.

I particularily remember a 30-second clip of my son swimming for the first 
time. There was a lot of sun sparkles in the wavelets around him, and I could 
really not get any good compression at all without getting block artifacts.

("Good compression" in my case means good enough to show on the TV using a 
Philips SL-400 media client, which works best with Xvid, bitrate < 1200. I 
usually shoot 320x240, 30fps)

That said, generally I get satisfactory results with

mencoder -ffourcc "DIVX" "$INP" -o "$OUT" -oac lavc -ovc lavc -srate 48000 
-lavcopts vcodec=mpeg4:acodec=mp3:abitrate=128:vbitrate=400

where INP and OUT are variables for input and output. Note that I do not use 
2-pass encoding, as I've found there is not much to gain on these short 
clips. On the other hand, there is perhaps not much to lose except CPU 
cycles...  You might also want to add a noise filter.

/Lennart

måndag 11 september 2006 19:29 skrev Strong:
> I have photo camera Canon A610 that produces video movies (mplayer
> says it is mjpeg) at 30 fps. Some second over 4 minutes of this video
> takes 512Mb! I believe I can have *the very same* movie quality at less
> capacity. So, as have tried not few the mencoder command line
> combinations and was not satisfied with the quality, I give my
> questions to those who are more expert with it.
>
> My question is, What is the mencoder command line that will compress in
> mpeg4 saving the same picture quality, visually?
>
> Second question is, How to reduce the noise value the camera produces
> at the least quality loosing?
>
> Between quality/size choosing the choice must be given to quality.
>
>
> Thank You for Your time and desire to share Your experience.
>
> PS Please, any questions. I will answer.
> _______________________________________________
> MEncoder-users mailing list
> MEncoder-users at mplayerhq.hu
> http://lists.mplayerhq.hu/mailman/listinfo/mencoder-users

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