linuxgeek: Re: [LINUX_Newbies] more questions about videos thank You to Scott

Friday, January 22, 2016

Re: [LINUX_Newbies] more questions about videos thank You to Scott

On Fri, Jan 22, 2016 at 01:29:38PM +0100, 'highskywhy@yahoo.de' highskywhy@yahoo.de [LINUX_Newbies] wrote:
> > >

> > > Questions:
> > > > Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p, 720x576
> > >
> > > Is this the most important line for my problem?
> >
> > Yes, that is referring to the codec of the video. (In this case, x264)
> *
> OK
> so
> can I do those things:
>
> Stream #0:0: Video: h264 (High) (H264 / 0x34363248), yuv420p, 720x576
> Make the quality of every picture worse by reduce the size of picture?
>
> Is it possible to split every ṕicture of a video.
>
> Example
>
>
> 11111
> 22222
> 33333
> 44444
>
>
>
>
> You can see this picture during 2 minutes video.
>
> can ffmpeg do that?

Yes.
If you want the first two minutes of the video

ffmpeg -i myvideo.avi -t 120 1111.avi

The -t is for time, usually in seconds. (So if you want two minutes, use
120.)

Then if you want the next two minutes

ffmpeg -ss 121 myvideo.avi -t 120 2222.avi

The -ss is to seek position. It is not exact, but it should be close
enough for your purpose. It should be before the -i <video-name>
otherwise, it takes a much longer time.

>
> or can
> split ffmpeg
>
>
> 11
> 22
> 33
> 44
> 55
>
I'm not sure what you mean by this.

>
> and can I make with ffmpeg out of a 2 minutes video an one hour video
> by making copy paste 59 times like a time loop?

I've never looked into that. You can make a repeating gif easily enough.
>
ffmpeg -i input -vf scale=320:-1 -r 10 -f image2pipe -vcodec ppm - |
convert -delay 5 -loop 0 - output.gif

Which might be easier. Otherwise, I'd probably use a different command.
My page talks about combining videos into one. The easiest thing to use is
mkvtoolnix and use mkvmerge -o myfile file1 + file2 + file3.

>
> I can convert a pic from 300 dpi to 100dpi
> and can I convert a video to any size or are there some sizes only possible?
>
There are probably some sizes that wouldn't work, I don't know them by
heart. :)

>
> Question:
> Here is a video a.avi with 1 GB
> now I reduce the size of the picture to 25% and same avi-container.
>
> Is now the space for the file 250 MB or less and the sound is the same?
>
> Regards Sophie

Sound would probably be the same, assuming you copy the audio. Do you mean
reduce it so it's 25 percent smaller or reduce it 75 percent so that it's
only 256 MB total size? You will probably lose a lot of quality.
>
>

--
Scott Robbins
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