lavf/http: fix/extend option descriptions

In particular, favor predicative form over nominal description of the set
parameter. This is more globally consistent.

libavformat/http.c

@@ -71,15 +71,15 @@ typedef struct {
 #define E AV_OPT_FLAG_ENCODING_PARAM
 #define DEC AV_OPT_FLAG_DECODING_PARAM
 static const AVOption options[] = {
-{"seekable", "Control seekability of connection", OFFSET(seekable), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, D },
+{"seekable", "control seekability of connection", OFFSET(seekable), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, D },
 {"chunked_post", "use chunked transfer-encoding for posts", OFFSET(chunked_post), AV_OPT_TYPE_INT, {.i64 = 1}, 0, 1, E },
-{"headers", "custom HTTP headers, can override built in default headers", OFFSET(headers), AV_OPT_TYPE_STRING, { 0 }, 0, 0, D|E },
+{"headers", "set custom HTTP headers, can override built in default headers", OFFSET(headers), AV_OPT_TYPE_STRING, { 0 }, 0, 0, D|E },
 {"content_type", "force a content type", OFFSET(content_type), AV_OPT_TYPE_STRING, { 0 }, 0, 0, D|E },
 {"user-agent", "override User-Agent header", OFFSET(user_agent), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC},
 {"multiple_requests", "use persistent connections", OFFSET(multiple_requests), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 1, D|E },
-{"post_data", "custom HTTP post data", OFFSET(post_data), AV_OPT_TYPE_BINARY, .flags = D|E },
-{"timeout", "timeout of socket i/o operations", OFFSET(rw_timeout), AV_OPT_TYPE_INT, {.i64 = -1}, -1, INT_MAX, D|E },
-{"mime_type", "", OFFSET(mime_type), AV_OPT_TYPE_STRING, {0}, 0, 0, 0 },
+{"post_data", "set custom HTTP post data", OFFSET(post_data), AV_OPT_TYPE_BINARY, .flags = D|E },
+{"timeout", "set timeout of socket I/O operations", OFFSET(rw_timeout), AV_OPT_TYPE_INT, {.i64 = -1}, -1, INT_MAX, D|E },
+{"mime_type", "set MIME type", OFFSET(mime_type), AV_OPT_TYPE_STRING, {0}, 0, 0, 0 },
 {NULL}
 };
 #define HTTP_CLASS(flavor)\