[FFmpeg-devel] Transcoding using FFmpeg

[Luca Barbato]

www.whu wrote:
> Hi All!

Hi

> I am a gradute student who is working on digital video transcoding. 
> I have found that FFmpeg is a powerful transcoding tool. So I decide to build my
> transcoding project on the basis of  it.

Let us know once you are done and we'll add your project to our
http://ffmpeg.mplayerhq.hu/projects.html

> But I got some problems.
> 1. I am not familiar with coding on  Linux. I spent lots of time on Windows 
> IDE like Visual C++/ Turbo C etc. So I got confused when I unpacked the 
> whole stuff.
> I want to know if you use an IDE such as Eclipse or you just coding the project
> in the terminal using an edtior like VI.

The nice part of using standard tools is that you can use whatever you
want and the end result will be the same, some people uses Eclipse C
module, some vim, some emacs, some nano, some other particular ides, in
the end you just issue or have your ide issue for you "./configure &&
make && make test" and you see the results =)

If you want some specific suggestions I advise you to post on
ffmpeg-users, since it is the right list to ask questions on ffmpeg usage.

> 2. Libavcodec contains a lot of codecs. I want to modify them and add my own property.
> For example: Transcoding from MPEG2 to MPEG4.
> I have to extract motion vectors from the MPEG2 code stream and then put them into MPEG4 
> code stream. However, MPEG2 and MPEG4 are different coding standards, so simply reusing 
> motion vectors will cause a lot problems.
> And also, I think analysing libavcodec is a very hard job.
> Is there any document about libavcodec?

http://ffmpeg.mplayerhq.hu/documentation.html

you can produce some of it using Doxygen.

> 3. Transcoding in FFmpeg is performed as  decoding then encoding. The computational
> complexity is very high compared with the partly decoding then partly encoding procedure.
> So do you want to add this feature to FFmpeg?

the idea of just adapting codec parameters w/out having a full
decode-encode is interesting, but I think it's quite limited to alike
codecs and could lead to really large code. If you manage to create a
map from mpeg2 to, say mpeg4 and h264, that is less cpu intensive but
gives comparable quality I think would be a nice addition to ffmpeg.

lu

-- 

Luca Barbato

Gentoo/linux Gentoo/PPC
http://dev.gentoo.org/~lu_zero