Add av_log_{ask_for_sample|missing_feature} replacements to libavutil

This allows reporting missing features and requesting samples from
all libraries in a standard way; with a simplified API.

2 files changed, 60 insertions, 0 deletions

diff --git a/libavutil/internal.h b/libavutil/internal.h
index 3cf55f6398..5f4b060926 100644
--- a/libavutil/internal.h
+++ b/libavutil/internal.h
@@ -162,4 +162,25 @@
 #   define ONLY_IF_THREADS_ENABLED(x) NULL
 #endif
 
+/**
+ * Log a generic warning message about a missing feature.
+ *
+ * @param[in] avc a pointer to an arbitrary struct of which the first
+ *                field is a pointer to an AVClass struct
+ * @param[in] msg string containing the name of the missing feature
+ */
+void avpriv_report_missing_feature(void *avc,
+                                   const char *msg, ...) av_printf_format(2, 3);
+
+/**
+ * Log a generic warning message about a missing feature.
+ * Additionally request that a sample showcasing the feature be uploaded.
+ *
+ * @param[in] avc a pointer to an arbitrary struct of which the first field is
+ *                a pointer to an AVClass struct
+ * @param[in] msg string containing the name of the missing feature
+ */
+void avpriv_request_sample(void *avc,
+                           const char *msg, ...) av_printf_format(2, 3);
+
 #endif /* AVUTIL_INTERNAL_H */
diff --git a/libavutil/log.c b/libavutil/log.c
index 80129769f6..bd46b0c054 100644
--- a/libavutil/log.c
+++ b/libavutil/log.c
@@ -32,10 +32,12 @@
 #if HAVE_IO_H
 #include <io.h>
 #endif
+#include <stdarg.h>
 #include <stdlib.h>
 #include "avstring.h"
 #include "avutil.h"
 #include "common.h"
+#include "internal.h"
 #include "log.h"
 
 static int av_log_level = AV_LOG_INFO;
@@ -179,3 +181,40 @@ void av_log_set_callback(void (*callback)(void*, int, const char*, va_list))
 {
     av_log_callback = callback;
 }
+
+static void missing_feature_sample(int sample, void *avc, const char *msg, ...)
+{
+    va_list argument_list;
+
+    va_start(argument_list, msg);
+
+    av_vlog(avc, AV_LOG_WARNING, msg, argument_list);
+    av_log(avc, AV_LOG_WARNING, " is not implemented. Update your Libav "
+           "version to the newest one from Git. If the problem still "
+           "occurs, it means that your file has a feature which has not "
+           "been implemented.\n");
+    if (sample)
+        av_log(avc, AV_LOG_WARNING, "If you want to help, upload a sample "
+               "of this file to ftp://upload.libav.org/incoming/ "
+               "and contact the libav-devel mailing list.\n");
+
+    va_end(argument_list);
+}
+
+void avpriv_request_sample(void *avc, const char *msg, ...)
+{
+    va_list argument_list;
+
+    va_start(argument_list, msg);
+    missing_feature_sample(1, avc, msg, argument_list);
+    va_end(argument_list);
+}
+
+void avpriv_report_missing_feature(void *avc, const char *msg, ...)
+{
+    va_list argument_list;
+
+    va_start(argument_list, msg);
+    missing_feature_sample(0, avc, msg, argument_list);
+    va_end(argument_list);
+}