tools/ffhash: implement base64 output.

Also fix usage string: the algorithm is not optional.

tools/ffhash.c

@@ -21,6 +21,7 @@
  */
 
 #include "config.h"
+#include "libavutil/avstring.h"
 #include "libavutil/error.h"
 #include "libavutil/hash.h"
 #include "libavutil/mem.h"
@@ -40,13 +41,14 @@
 #define SIZE 65536
 
 static struct AVHashContext *hash;
+static int out_b64;
 
 static void usage(void)
 {
     int i = 0;
     const char *name;
 
-    printf("usage: ffhash [algorithm] [input]...\n");
+    printf("usage: ffhash [b64:]algorithm [input]...\n");
     printf("Supported hash algorithms:");
     do {
         name = av_hash_names(i);
@@ -59,10 +61,16 @@ static void usage(void)
 
 static void finish(void)
 {
-    char res[2 * AV_HASH_MAX_SIZE + 1];
+    char res[2 * AV_HASH_MAX_SIZE + 4];
 
+    printf("%s=", av_hash_get_name(hash));
+    if (out_b64) {
+        av_hash_final_b64(hash, res, sizeof(res));
+        printf("b64:%s", res);
+    } else {
         av_hash_final_hex(hash, res, sizeof(res));
-    printf("%s=0x%s", av_hash_get_name(hash), res);
+        printf("0x%s", res);
+    }
 }
 
 static int check(char *file)
@@ -110,16 +118,19 @@ int main(int argc, char **argv)
 {
     int i;
     int ret = 0;
+    const char *hash_name;
 
     if (argc == 1) {
         usage();
         return 0;
     }
 
-    if ((ret = av_hash_alloc(&hash, argv[1])) < 0) {
+    hash_name = argv[1];
+    out_b64 = av_strstart(hash_name, "b64:", &hash_name);
+    if ((ret = av_hash_alloc(&hash, hash_name)) < 0) {
         switch(ret) {
         case AVERROR(EINVAL):
-            printf("Invalid hash type: %s\n", argv[1]);
+            printf("Invalid hash type: %s\n", hash_name);
             break;
         case AVERROR(ENOMEM):
             printf("%s\n", strerror(errno));