lavd/avdevice: add device iterators

Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/libavdevice/avdevice.c b/libavdevice/avdevice.c
index 9e2b7d52da..8964b96f36 100644
--- a/libavdevice/avdevice.c
+++ b/libavdevice/avdevice.c
@@ -37,6 +37,52 @@ const char * avdevice_license(void)
     return LICENSE_PREFIX FFMPEG_LICENSE + sizeof(LICENSE_PREFIX) - 1;
 }
 
+static void *av_device_next(void *prev, int output,
+                            AVClassCategory c1, AVClassCategory c2)
+{
+    const AVClass *pc;
+    AVClassCategory category = AV_CLASS_CATEGORY_NA;
+    do {
+        if (output) {
+            if (!(prev = av_oformat_next(prev)))
+                break;
+            pc = ((AVOutputFormat *)prev)->priv_class;
+        } else {
+            if (!(prev = av_iformat_next(prev)))
+                break;
+            pc = ((AVInputFormat *)prev)->priv_class;
+        }
+        if (!pc)
+            continue;
+        category = pc->category;
+    } while (category != c1 && category != c2);
+    return prev;
+}
+
+AVInputFormat *av_input_audio_device_next(AVInputFormat  *d)
+{
+    return av_device_next(d, 0, AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
+                          AV_CLASS_CATEGORY_DEVICE_INPUT);
+}
+
+AVInputFormat *av_input_video_device_next(AVInputFormat  *d)
+{
+    return av_device_next(d, 0, AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
+                          AV_CLASS_CATEGORY_DEVICE_INPUT);
+}
+
+AVOutputFormat *av_output_audio_device_next(AVOutputFormat *d)
+{
+    return av_device_next(d, 1, AV_CLASS_CATEGORY_DEVICE_AUDIO_OUTPUT,
+                          AV_CLASS_CATEGORY_DEVICE_OUTPUT);
+}
+
+AVOutputFormat *av_output_video_device_next(AVOutputFormat *d)
+{
+    return av_device_next(d, 1, AV_CLASS_CATEGORY_DEVICE_VIDEO_OUTPUT,
+                          AV_CLASS_CATEGORY_DEVICE_OUTPUT);
+}
+
 int avdevice_app_to_dev_control_message(struct AVFormatContext *s, enum AVAppToDevMessageType type,
                                         void *data, size_t data_size)
 {