[FFmpeg-devel] [PATCH] Add AVOptions for libopenh264 encoder message log level and log function.

Gregory J Wolfe gregory.wolfe at kodakalaris.com
Wed Sep 2 19:36:30 CEST 2015 

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Paul B Mahol
> Sent: Wednesday, September 02, 2015 1:15 PM
> To: FFmpeg development discussions and patches
> Subject: Re: [FFmpeg-devel] [PATCH] Add AVOptions for libopenh264
> encoder message log level and log function.
> 
> Dana 2. 9. 2015. 19:10 osoba "Gregory J. Wolfe" <
> gregory.wolfe at kodakalaris.com> napisala je:
> >
> > By default, the libopenh264 encoder logs error and warning messages to
> > stderr.  However, libopenh264 also provides a SetOption() function
> > that allows the client to set the message logging level (e.g., error,
> > warning,
> > debug) and a client-supplied message logging function (whose signature
> > must conform to libopenh264 type WelsTraceCallback).
> >
> > To enable this from the FFmpeg level, file libopenh264enc.c has been
> > modified to add AVOption entries OPTION_TRACEL_LEVEL (log level) and
> > OPTION_TRACE_CALLBACK (log function).  The names are derived from the
> > enumerator values ENCODER_OPTION_TRACE_LEVEL and
> > ENCODER_OPTION_TRACE_CALLBACK which are passed to SetOption().
> While
> > they are somewhat verbose, they are very likely unique across encoders.
> >
> > Some FFmpeg command line examples.  To disable all libopenh264
> messages:
> >
> >   ffmpeg ... -OPTION_TRACE_LEVEL quiet
> >
> > To enable only error messages:
> >
> >   ffmpeg ... -OPTION_TRACE_LEVEL error
> >
> > The OPTION_TRACE_CALLBACK option can obviously not be used from the
> > command line since it requires the address of a function.  When used
> > programmatically, the function address must be converted to a string
> > representation of the function address as a signed 64-bit integer.
> >
> > The function signature defined by libopenh264 type WelsTraceCallback
> > can be found in source file codec/api/svc/codec_api.h.  The default
> > implementation used by libopenh264 is function welsStderrTrace(), and
> > can be found in source file codec/common/source/welsCodecTrace.cpp.
> 
> Why this doesnt make use of av_log functions?

The libopenh264 library requires its own specific signature for the log function
that you give to it.  If the client so desires, he/she can create a message
logging function with the required libopenh264 signature that then invokes
av_log.  Note that libopenh264 already formats its messages using its own
prefix strings, similar to what FFmpeg does.

> 
> CAPS LOCK OPTIONS ARE UNACCEPTABLE
> 

I'm guessing that you're objecting to the command line switch values like
-OPTION_TRACE_LEVEL.  I did not want to use something like loglevel
since it is already used by FFmpeg.  libopenh264 uses its own
enumerator values for its message logging level, so I simply
tried to come up with something that would not conflict with any existing
AVOptions.  Do the AVOption keywords have to be unique across all
formats/encoders/decoders?  Please supply some guidance as to
requirements/restrictions and I will be happy to update the patch.

> >
> > Signed-off-by: Gregory J. Wolfe <gregory.wolfe at kodakalaris.com>
> > ---
> >  libavcodec/libopenh264enc.c | 22 ++++++++++++++++++++++
> >  1 file changed, 22 insertions(+)
> >
> > diff --git a/libavcodec/libopenh264enc.c b/libavcodec/libopenh264enc.c
> > index b315e8b..146bbaf 100644
> > --- a/libavcodec/libopenh264enc.c
> > +++ b/libavcodec/libopenh264enc.c
> > @@ -37,6 +37,9 @@ typedef struct SVCContext {
> >      int slice_mode;
> >      int loopfilter;
> >      char *profile;
> > +    int OPTION_TRACE_LEVEL;
> > +    int64_t OPTION_TRACE_CALLBACK;  // message logging function, type is
> > +                                    // actually WelsTraceCallback
> >  } SVCContext;
> >
> >  #define OPENH264_VER_AT_LEAST(maj, min) \ @@ -52,6 +55,17 @@
> static
> > const AVOption options[] = {
> >      { "auto", "Automatic number of slices according to number of
> threads", 0, AV_OPT_TYPE_CONST, { .i64 = SM_AUTO_SLICE }, 0, 0, VE,
> "slice_mode" },
> >      { "loopfilter", "Enable loop filter", OFFSET(loopfilter),
> AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, VE },
> >      { "profile", "Set profile restrictions", OFFSET(profile),
> AV_OPT_TYPE_STRING, { 0 }, 0, 0, VE },
> > +    { "OPTION_TRACE_LEVEL", "Message logging level",
> OFFSET(OPTION_TRACE_LEVEL), AV_OPT_TYPE_INT, { .i64 =
> WELS_LOG_DEFAULT }, WELS_LOG_QUIET, WELS_LOG_RESV, VE,
> "OPTION_TRACE_LEVEL" },
> > +    { "default", "default libopenh264 message logging", 0,
> AV_OPT_TYPE_CONST, { .i64 = WELS_LOG_DEFAULT }, 0, 0, VE,
> "OPTION_TRACE_LEVEL" },
> > +    { "quiet", "quiet mode", 0, AV_OPT_TYPE_CONST, { .i64 =
> WELS_LOG_QUIET }, 0, 0, VE, "OPTION_TRACE_LEVEL" },
> > +    { "error", "log error messages", 0, AV_OPT_TYPE_CONST, { .i64 =
> WELS_LOG_ERROR }, 0, 0, VE, "OPTION_TRACE_LEVEL" },
> > +    { "warning", "log warning+err messages", 0, AV_OPT_TYPE_CONST, {
> .i64 = WELS_LOG_WARNING }, 0, 0, VE, "OPTION_TRACE_LEVEL" },
> > +    { "info", "log informational+wrn+err messages", 0,
> AV_OPT_TYPE_CONST, { .i64 = WELS_LOG_INFO }, 0, 0, VE,
> "OPTION_TRACE_LEVEL"
> },
> > +    { "debug", "log debug+inf+wrn+err messages", 0,
> > + AV_OPT_TYPE_CONST, {
> .i64 = WELS_LOG_DEBUG }, 0, 0, VE, "OPTION_TRACE_LEVEL" },
> > +    { "detail", "log detail+dbg+inf+wrn+err messages", 0,
> AV_OPT_TYPE_CONST, { .i64 = WELS_LOG_DETAIL }, 0, 0, VE,
> "OPTION_TRACE_LEVEL" },
> > +    // for OPTION_TRACE_CALLBACK, default value of 0 means do not
> change; otherwise, it is the
> > +    // address of the WelsTraceCallback message logging function,
> > + passed
> in as an int64_t
> > +    { "OPTION_TRACE_CALLBACK", "Message logging function, 0 means do
> > + not
> change", OFFSET(OPTION_TRACE_CALLBACK), AV_OPT_TYPE_INT64, { .i64 =
> 0 }, INT64_MIN, INT64_MAX, VE, "OPTION_TRACE_CALLBACK" },
> >      { NULL }
> >  };
> >
> > @@ -89,6 +103,14 @@ static av_cold int svc_encode_init(AVCodecContext
> *avctx)
> >          av_log(avctx, AV_LOG_ERROR, "Unable to create encoder\n");
> >          return AVERROR_UNKNOWN;
> >      }
> > +    // set message logging options
> > +    // message logging level
> > +
> (*s->encoder)->SetOption(s-
> >encoder,ENCODER_OPTION_TRACE_LEVEL,&s->OPTION_TRACE_LEVEL);
> > +    if  ( s->OPTION_TRACE_CALLBACK )
> > +    {//set message logging function
> > +        WelsTraceCallback OPTION_TRACE_CALLBACK = (WelsTraceCallback)
> ((uintptr_t)s->OPTION_TRACE_CALLBACK);
> > +
> (*s->encoder)->SetOption(s-
> >encoder,ENCODER_OPTION_TRACE_CALLBACK,(void
> *)&OPTION_TRACE_CALLBACK);
> > +    }//set message logging function
> >
> >      (*s->encoder)->GetDefaultParams(s->encoder, &param);
> >
> > --
> > 1.8.5.2.msysgit.0
> >
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> > ffmpeg-devel at ffmpeg.org
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