[aklug] Re: Converting ogv to mp4

I occasionally watch the videos available on Linux Journal's Website. I
was just watching one that appears to be a recording of some desktop
operations and I noticed that it is available to download in either ogv
or mp4.

The ogv is 16.4 MB, the mp4 is 49.5 MB. I won't go so far as to claim
the guys are the last word on the subject, but ...

http://www.linuxjournal.com/video/working-suse-studio

Also doesn't answer the question of "Why?", and I sure don't know.

Jim G

On Tue, 2010-04-20 at 22:02 -0800, Shane Spencer wrote:
> It depends on how the frames were set up. For a screencast
> theora/h.264/mpeg/flv/gif will work pretty well if you assume you need
> very few intermediate frames. Since you used a screen recorder
> chances are the theora stream was encoded with that in mind.
> Converting it may have introduced more full frames.
>
> I'm guessing media delivery is done using using TCP for the final
> stream.. Try converting it with ffmpeg and control how often full
> frame updates are made.
>
> Also, you may end up tricking the other codec and causing a larger
> output by not smoothing the original input to remove the visual
> boundary on all motion blocks. This is important if you're encoding
> to a "natural" codec like h.264 since it would really really like to
> not have to encode straight lines left behind from one block size into
> a stream that uses a different block size. If the original source
> looks fine then this may not be the case.. but I've seen some
> transcoding from low bitrate mpeg4 to other formats get larger in some
> areas of the stream due to this.
>
> - Shane
>
> On Tue, Apr 20, 2010 at 10:22 AM, damien hull <damien@linuxninjas.tv> wrote=
> :
> > I'm trying to do a screen cast. I used record my desktop to capture the s=
> creencast. That saves it in ogv format. That's the open source ogg theora f=
> ormat. The file size was something like 160 megabytes or something like tha=
> t. I used the video editor kdenlive to convert the video into an h264 encod=
> ed mp4 video file at 8000k. I think that 800k is the bit rate. Anyway, the =
> file size was something like 240 megabytes.
> >
> > Why is the mp4 video file larger then the ogv file? Shouldn't it be going=
> down in size? I must be missing something here.
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Received on Sun Apr 25 16:29:27 2010