[FFmpeg-devel] Touching base on first decoder ( CDXL ) before loosing direction

Michael Niedermayer michaelni
Tue Apr 7 22:31:58 CEST 2009

On Tue, Apr 07, 2009 at 02:30:00PM -0500, Erion Omeri wrote:
> Hello,
> I just wanted to check base with the team before I get off track.
> QUESTION: Am I in the right path to creating the CDXL codec (see files)?

pretty much any not trivial contribution to ffmpeg is ok as
qual task, ...

> I read the Wiki and the simple Cook decoder:
> http://wiki.multimedia.cx/index.php?title=FFmpeg_codec_howto
>  I found the Pascal version of the CDXL decoder and have loosely tried to
> convert it to C ( not done by any means). I did focus mainly on the READ
> function.
> I have made some generalizations and will have to make more as we go along.
> http://aminet.net/package/gfx/show/AnimFX
>  I understand that there is not much time left to get this qualification
> task up and running, so I will attach my files here so that you can see what
> direction I am going. I have commented out a skeleton I grabbed from another
> codec example and will eventually adapt my functions to using the FFMPEG
> interface.

> I understand that in order to add a codec to the pool I will need to its ID
> in a struct in AVCodec but if the order of that struct changes other
> dependencies break. How do I go about adding my codec ID without breaking
> the rest, should I just add it at the tail? On the other hand, I see
> grouping in the struct which makes think it should go under video codecs
> which is not at the tail.

how to add a value into a enum without changing the existing values and
still do it close to a semantically nice spot is basic C knowledge which
is a prerequestite for as sucessfull gsoc ffmpeg project

> I would also need to make an addition on the Make file to link my cdxl.o and
> its dependencies to the rest.
> Do you guys have a procedure to test make your codecs while programming
> without the overwhelming verbose and time consuming make?

"make test" will test the existing stuff
and "ffplay some_cdxl_file" will test your newly added code

> Also how much time is allowed to complete the qualification tasks?

until google freezes the choice of the accepted applications, also
keep in mind that code must pass review and this needs many iterations
that is
you submit patch -> we review -> it passed review -> we change the choosen
apps must happen prior to googles deadline.

also you should read our developers guide

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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