[FFmpeg-devel] [RFC] print license and configuration for each lib

[Stefano Sabatini]

On date Friday 2009-10-30 18:51:23 +0100, Diego Biurrun encoded:
> On Wed, Oct 28, 2009 at 06:59:11PM +0000, M?ns Rullg?rd wrote:
> > Diego Biurrun <diego at biurrun.de> writes:
> > 
> > > Here's something I started and wanted to have some feedback on before I
> > > progress.  Sometimes it can be useful to have the exact configuration
> > > and license string in each library and have it printed by each library.
> > >
> > > Here is a proof of concept patch that does it for libavutil and
> > > libavcodec.  Once the chinks are worked out I can lather, rinse, repeat
> > > for the others.
> > >
> > > I made two alternative implementations, choose the one you prefer.
> > > Things that could possibly be improved (but might not be worth the
> > > trouble):
> > >
> > > - The licensing information for each library could be more detailed.
> > >   For example, libavutil is always LGPL, even when FFmpeg was compiled
> > >   in GPL mode.
> > > - Use a single function to perform the job.
> > >
> > > +void avutil_configuration(void)
> > > +{
> > > +    const char* configuration = "libavutil configuration: " FFMPEG_CONFIGURATION;
> > > +    av_log(NULL, AV_LOG_INFO, "%s\n", configuration);
> > > +}
> > > +
> > > +void avutil_license(void)
> > > +{
> > > +    const char* libavutil_license = "libavutil license: "FFMPEG_LICENSE;
> > > +    av_log(NULL, AV_LOG_INFO, "%s\n", libavutil_license);
> > > +}
> > 
> > Returning the string would probably be more flexible.
> 
> Like I have done in $attached for libavcodec?  Anything else?
> 
> Diego

> Index: configure
> ===================================================================
> --- configure	(Revision 20419)
> +++ configure	(Arbeitskopie)
> @@ -2751,6 +2751,7 @@
>  echo "#ifndef FFMPEG_CONFIG_H" >> $TMPH
>  echo "#define FFMPEG_CONFIG_H" >> $TMPH
>  echo "#define FFMPEG_CONFIGURATION \"$(c_escape $FFMPEG_CONFIGURATION)\"" >> $TMPH
> +echo "#define FFMPEG_LICENSE \"$(c_escape $license)\"" >> $TMPH
>  echo "#define FFMPEG_DATADIR \"$(eval c_escape $datadir)\"" >> $TMPH
>  
>  echo "#define CC_TYPE \"$cc_type\"" >> $TMPH
> Index: libavcodec/avcodec.h
> ===================================================================
> --- libavcodec/avcodec.h	(Revision 20419)
> +++ libavcodec/avcodec.h	(Arbeitskopie)
> @@ -3062,6 +3062,16 @@
>  unsigned avcodec_version(void);
>  
>  /**
> + * Prints the libavcodec build-time configuration.
> + */
> +const char* avcodec_configuration(void);

Nit: "const char* " -> "const char *", here and below.

> +
> +/**
> + * Prints the libavcodec license.
> + */
> +const char* avcodec_license(void);


> +/**
>   * Initializes libavcodec.
>   *
>   * @warning This function must be called before any other libavcodec
> Index: libavcodec/utils.c
> ===================================================================
> --- libavcodec/utils.c	(Revision 20419)
> +++ libavcodec/utils.c	(Arbeitskopie)
> @@ -924,6 +924,16 @@
>    return LIBAVCODEC_VERSION_INT;
>  }
>  
> +const char* avcodec_configuration(void)
> +{
> +    return "libavcodec configuration: " FFMPEG_CONFIGURATION "\n";
> +}
>
> +
> +const char* avcodec_license(void)
> +{
> +    return "libavcodec license: " FFMPEG_LICENSE "\n";
> +}
>
> +
>  void avcodec_init(void)
>  {
>      static int initialized = 0;
> Index: cmdutils.c
> ===================================================================
> --- cmdutils.c	(Revision 20419)
> +++ cmdutils.c	(Arbeitskopie)
> @@ -317,6 +317,8 @@
>  {
>      unsigned int version;
>      PRINT_LIB_VERSION(outstream, avutil,   AVUTIL,   indent);
> +    fprintf(stderr, avcodec_configuration());
> +    fprintf(stderr, avcodec_license());

Why not to extend the PRINT_LIB_VERSION macro?
Then it could be renamed e.g. PRINT_LIB_INFO().

>      PRINT_LIB_VERSION(outstream, avcodec,  AVCODEC,  indent);
>      PRINT_LIB_VERSION(outstream, avformat, AVFORMAT, indent);
>      PRINT_LIB_VERSION(outstream, avdevice, AVDEVICE, indent);

Anyway IMO would be better *before to apply this*, to work out some
way to provide per-library licensing information, rather than spit-out
wrong informations, e.g. lavu showing up a nonfree/GPL license.

Regards.
-- 
FFmpeg = Fiendish and Fostering Meaningless Powerful Ecletic God