[FFmpeg-devel] [RFC] Split libavformat

[Ramiro Ribeiro Polla]

Hello,

Luca Abeni wrote:
> Hi all,
> 
> as promised, here is my attempt at splitting libavformat.

Sorry for not working any further on this. After all, summer is starting 
and I live in a sub-tropical island, so it's quite hard to concentrate...

> The attached patches create 2 more libraries: libavdevice (mainly
> containing formats for getting audio and video from grabbing
> devices, but it might contain more things in the future) and
> libavnet (containing all the networking-related code).
> 
[...]
> Index: ffmpeg/libavdevice/Makefile
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ ffmpeg/libavdevice/Makefile	2007-11-19 19:57:22.061554240 +0100
[...]
> +
> +# external libraries
> +OBJS-$(CONFIG_LIBDC1394_DEMUXER)         += libdc1394.o

Sure, this lib is for grabbing devices, but it is also an external 
library. What about also splitting external libraries out of libav* too? 
(think pure libavformat/codec with no depencies at all).

> Index: ffmpeg/libavdevice/allformats.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ ffmpeg/libavdevice/allformats.c	2007-11-19 19:57:22.062554088 +0100
[...]
> +void avdevice_register_all(void)
> +{
> +    static int inited;
> +
> +    if (inited)
> +        return;
> +    inited = 1;
> +
> +    av_register_all();
[...]
 > Index: ffmpeg/ffmpeg.c
 > ===================================================================
 > --- ffmpeg.orig/ffmpeg.c	2007-11-19 19:49:07.299769464 +0100
 > +++ ffmpeg/ffmpeg.c	2007-11-19 19:57:22.065553632 +0100
 > @@ -28,6 +28,7 @@
 >  #include <signal.h>
 >  #include <limits.h>
 >  #include "avformat.h"
 > +#include "avdevice.h"
 >  #include "swscale.h"
 >  #include "framehook.h"
 >  #include "opt.h"
 > @@ -3883,7 +3884,7 @@
 >      int i;
 >      int64_t ti;
 >
 > -    av_register_all();
 > +    avdevice_register_all();

Since we're breaking API already, to avoid this recursive calling of 
av_register_all and deciding which register_all function to call, how 
about "the user MUST initialize every library", as in:

avcodec_register_all();
avformat_register_all();
avdevice_register_all();
...

and remove av_register_all() (since it would cause dependencies to other 
libraries).

[...]

> --- ffmpeg.orig/libavformat/allformats.c	2007-11-19 19:57:22.062554088 +0100
> +++ ffmpeg/libavformat/allformats.c	2007-11-19 20:09:18.796593952 +0100
[...]
>      /* protocols */
>      REGISTER_PROTOCOL (FILE, file);
> -    REGISTER_PROTOCOL (HTTP, http);
>      REGISTER_PROTOCOL (PIPE, pipe);
> -    REGISTER_PROTOCOL (RTP, rtp);
> -    REGISTER_PROTOCOL (TCP, tcp);
> -    REGISTER_PROTOCOL (UDP, udp);

Regarding keeping file_protocol and pipe_protocol (already questioned 
and answered on [1]), well, libav* already depend on libavutil. I don't 
see any harm on them also depending on libavprotocol. That would 
entirely isolate libavformat from any OS I/O stuff.

[...]

Just my R$0.02.

Great job, and sorry again for not taking it further =(

I'm off to the beach now...

Ramiro Polla
[1] http://article.gmane.org/gmane.comp.video.ffmpeg.devel/59602