lavu/opt: introduce av_opt_serialize()

Function allows to create string containing object's serialized options.
Such string may be passed back to av_set_options_string() in order to restore options.
Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2014-08-09
 
 API changes, most recent first:
 
+2014-11-16 - xxxxxxx - lavu 54.13.0 - opt.h
+  Add av_opt_serialize().
+
 2014-11-16 - xxxxxxx - lavu 54.12.0 - opt.h
   Add av_opt_is_set_to_default().
 

libavutil/opt.c

@@ -37,6 +37,7 @@
 #include "pixdesc.h"
 #include "mathematics.h"
 #include "samplefmt.h"
+#include "bprint.h"
 
 #include <float.h>
 
@@ -1835,6 +1836,44 @@ int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_fla
     return av_opt_is_set_to_default(target, o);
 }
 
+int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
+                     const char key_val_sep, const char pairs_sep)
+{
+    const AVOption *o = NULL;
+    uint8_t *buf;
+    AVBPrint bprint;
+    int ret, cnt = 0;
+
+    if (!obj || !buffer)
+        return AVERROR(EINVAL);
+
+    *buffer = NULL;
+    av_bprint_init(&bprint, 64, AV_BPRINT_SIZE_UNLIMITED);
+
+    while (o = av_opt_next(obj, o)) {
+        if (o->type == AV_OPT_TYPE_CONST)
+            continue;
+        if ((flags & AV_OPT_SERIALIZE_OPT_FLAGS_EXACT) && o->flags != opt_flags)
+            continue;
+        else if (((o->flags & opt_flags) != opt_flags))
+            continue;
+        if (flags & AV_OPT_SERIALIZE_SKIP_DEFAULTS && av_opt_is_set_to_default(obj, o) > 0)
+            continue;
+        if ((ret = av_opt_get(obj, o->name, 0, &buf)) < 0) {
+            av_bprint_finalize(&bprint, NULL);
+            return ret;
+        }
+        if (buf) {
+            if (cnt++)
+                av_bprint_append_data(&bprint, &pairs_sep, 1);
+            av_bprintf(&bprint, "%s%c%s", o->name, key_val_sep, buf);
+            av_freep(&buf);
+        }
+    }
+    av_bprint_finalize(&bprint, buffer);
+    return 0;
+}
+
 #ifdef TEST
 
 typedef struct TestContext
@@ -1854,6 +1893,10 @@ typedef struct TestContext
     int64_t channel_layout;
     void *binary;
     int binary_size;
+    void *binary1;
+    int binary_size1;
+    void *binary2;
+    int binary_size2;
     int64_t num64;
     float flt;
     double dbl;
@@ -1882,6 +1925,8 @@ static const AVOption test_options[]= {
 {"color", "set color",   OFFSET(color), AV_OPT_TYPE_COLOR, {.str = "pink"}, 0, 0},
 {"cl", "set channel layout", OFFSET(channel_layout), AV_OPT_TYPE_CHANNEL_LAYOUT, {.i64 = AV_CH_LAYOUT_HEXAGONAL}, 0, INT64_MAX},
 {"bin", "set binary value",    OFFSET(binary),   AV_OPT_TYPE_BINARY,   {.str="62696e00"}, 0,        0 },
+{"bin1", "set binary value",   OFFSET(binary1),  AV_OPT_TYPE_BINARY,   {.str=NULL},       0,        0 },
+{"bin2", "set binary value",   OFFSET(binary2),  AV_OPT_TYPE_BINARY,   {.str=""},         0,        0 },
 {"num64",    "set num 64bit",  OFFSET(num64),    AV_OPT_TYPE_INT64,    {.i64 = 1},        0,        100 },
 {"flt",      "set float",      OFFSET(flt),      AV_OPT_TYPE_FLOAT,    {.dbl = 1.0/3},    0,        100 },
 {"dbl",      "set double",     OFFSET(dbl),      AV_OPT_TYPE_DOUBLE,   {.dbl = 1.0/3},    0,        100 },
@@ -1951,6 +1996,30 @@ int main(void)
         av_opt_free(&test_ctx);
     }
 
+    printf("\nTest av_opt_serialize()\n");
+    {
+        TestContext test_ctx = { 0 };
+        char *buf;
+        test_ctx.class = &test_class;
+
+        av_log_set_level(AV_LOG_QUIET);
+
+        av_opt_set_defaults(&test_ctx);
+        if (av_opt_serialize(&test_ctx, 0, 0, &buf, '=', ',') >= 0) {
+            printf("%s\n", buf);
+            av_opt_free(&test_ctx);
+            memset(&test_ctx, 0, sizeof(test_ctx));
+            test_ctx.class = &test_class;
+            av_set_options_string(&test_ctx, buf, "=", ",");
+            av_free(buf);
+            if (av_opt_serialize(&test_ctx, 0, 0, &buf, '=', ',') >= 0) {
+                printf("%s\n", buf);
+                av_free(buf);
+            }
+        }
+        av_opt_free(&test_ctx);
+    }
+
     printf("\nTesting av_set_options_string()\n");
     {
         TestContext test_ctx = { 0 };

libavutil/opt.h

@@ -869,6 +869,27 @@ int av_opt_is_set_to_default(void *obj, const AVOption *o);
  */
 int av_opt_is_set_to_default_by_name(void *obj, const char *name, int search_flags);
 
+
+#define AV_OPT_SERIALIZE_SKIP_DEFAULTS              0x00000001  ///< Serialize options that are not set to default values only.
+#define AV_OPT_SERIALIZE_OPT_FLAGS_EXACT            0x00000002  ///< Serialize options that exactly match opt_flags only.
+
+/**
+ * Serialize object's options.
+ *
+ * Create a string containing object's serialized options.
+ * Such string may be passed back to av_opt_set_from_string() in order to restore option values.
+ *
+ * @param[in]  obj           AVClass object to serialize
+ * @param[in]  opt_flags     serialize options with all the specified flags set (AV_OPT_FLAG)
+ * @param[in]  flags         combination of AV_OPT_SERIALIZE_* flags
+ * @param[out] buffer        Pointer to buffer that will be allocated with string containg serialized options.
+ *                           Buffer must be freed by the caller when is no longer needed.
+ * @param[in]  key_val_sep   character used to separate key from value
+ * @param[in]  pairs_sep     character used to separate two pairs from each other
+ * @return                   >= 0 on success, negative on error
+ */
+int av_opt_serialize(void *obj, int opt_flags, int flags, char **buffer,
+                     const char key_val_sep, const char pairs_sep);
 /**
  * @}
  */

libavutil/version.h

@@ -56,7 +56,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  54
-#define LIBAVUTIL_VERSION_MINOR  12
+#define LIBAVUTIL_VERSION_MINOR  13
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

tests/ref/fate/opt

@@ -34,6 +34,8 @@ name:  duration default:0 error:
 name:     color default:0 error:
 name:        cl default:0 error:
 name:       bin default:0 error:
+name:      bin1 default:1 error:
+name:      bin2 default:1 error:
 name:     num64 default:0 error:
 name:       flt default:0 error:
 name:       dbl default:0 error:
@@ -53,10 +55,16 @@ name:  duration default:1 error:
 name:     color default:1 error:
 name:        cl default:1 error:
 name:       bin default:1 error:
+name:      bin1 default:1 error:
+name:      bin2 default:1 error:
 name:     num64 default:1 error:
 name:       flt default:1 error:
 name:       dbl default:1 error:
 
+Test av_opt_serialize()
+num=0,toggle=1,rational=1/1,string=default,flags=0x00000001,size=200x300,pix_fmt=0bgr,sample_fmt=s16,video_rate=25/1,duration=0:00:00.001000,color=0xffc0cbff,cl=0x137,bin=62696E00,bin1=,bin2=,num64=1,flt=0.333333,dbl=0.333333
+num=0,toggle=1,rational=1/1,string=default,flags=0x00000001,size=200x300,pix_fmt=0bgr,sample_fmt=s16,video_rate=25/1,duration=0:00:00.001000,color=0xffc0cbff,cl=0x137,bin=62696E00,bin1=,bin2=,num64=1,flt=0.333333,dbl=0.333333
+
 Testing av_set_options_string()
 OK    ''
 Error ':'