cmdutils: use helper functions for listing sinks/sources

List device callback must be able to return valid list without opening device.
This callback should return input values for open function, not vice-versa.
Read header funtion is very likey to fail without proper configuration provided.
Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>

cmdutils.c

@@ -2076,9 +2076,7 @@ void *grow_array(void *array, int elem_size, int *size, int new_size)
 static int print_device_sources(AVInputFormat *fmt, AVDictionary *opts)
 {
     int ret, i;
-    AVFormatContext *dev = NULL;
     AVDeviceInfoList *device_list = NULL;
-    AVDictionary *tmp_opts = NULL;
 
     if (!fmt || !fmt->priv_class  || !AV_IS_INPUT_DEVICE(fmt->priv_class->category))
         return AVERROR(EINVAL);
@@ -2090,15 +2088,7 @@ static int print_device_sources(AVInputFormat *fmt, AVDictionary *opts)
         goto fail;
     }
 
-    /* TODO: avformat_open_input calls read_header callback which is not necessary.
-             Function like avformat_alloc_output_context2 for input could be helpful here. */
-    av_dict_copy(&tmp_opts, opts, 0);
-    if ((ret = avformat_open_input(&dev, NULL, fmt, &tmp_opts)) < 0) {
-        printf("Cannot open device: %s.\n", fmt->name);
-        goto fail;
-    }
-
-    if ((ret = avdevice_list_devices(dev, &device_list)) < 0) {
+    if ((ret = avdevice_list_input_sources(fmt, NULL, opts, &device_list)) < 0) {
         printf("Cannot list sources.\n");
         goto fail;
     }
@@ -2109,18 +2099,14 @@ static int print_device_sources(AVInputFormat *fmt, AVDictionary *opts)
     }
 
   fail:
-    av_dict_free(&tmp_opts);
     avdevice_free_list_devices(&device_list);
-    avformat_close_input(&dev);
     return ret;
 }
 
 static int print_device_sinks(AVOutputFormat *fmt, AVDictionary *opts)
 {
     int ret, i;
-    AVFormatContext *dev = NULL;
     AVDeviceInfoList *device_list = NULL;
-    AVDictionary *tmp_opts = NULL;
 
     if (!fmt || !fmt->priv_class  || !AV_IS_OUTPUT_DEVICE(fmt->priv_class->category))
         return AVERROR(EINVAL);
@@ -2132,14 +2118,7 @@ static int print_device_sinks(AVOutputFormat *fmt, AVDictionary *opts)
         goto fail;
     }
 
-    if ((ret = avformat_alloc_output_context2(&dev, fmt, NULL, NULL)) < 0) {
-        printf("Cannot open device: %s.\n", fmt->name);
-        goto fail;
-    }
-    av_dict_copy(&tmp_opts, opts, 0);
-    av_opt_set_dict2(dev, &tmp_opts, AV_OPT_SEARCH_CHILDREN);
-
-    if ((ret = avdevice_list_devices(dev, &device_list)) < 0) {
+    if ((ret = avdevice_list_output_sinks(fmt, NULL, opts, &device_list)) < 0) {
         printf("Cannot list sinks.\n");
         goto fail;
     }
@@ -2150,9 +2129,7 @@ static int print_device_sinks(AVOutputFormat *fmt, AVDictionary *opts)
     }
 
   fail:
-    av_dict_free(&tmp_opts);
     avdevice_free_list_devices(&device_list);
-    avformat_free_context(dev);
     return ret;
 }