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

[Gregory J. Wolfe]

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.

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