[aklug] Re: Converting ogv to mp4

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 Tue Apr 20 22:02:58 2010