lavd/avdevice: introduce helper functions for sink/sources listing

Signed-off-by: Lukasz Marek <lukasz.m.luki2@gmail.com>

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2014-08-09
 
 API changes, most recent first:
 
+2015-01-11 - xxxxxxx - lavd 56.4.100 - avdevice.h
+  Add avdevice_list_input_sources().
+  Add avdevice_list_output_sinks().
+
 201x-xx-xx - xxxxxxx - lavc 56.10.0 - vdpau.h
   Add av_vdpau_get_surface_parameters().
 

libavdevice/Makefile

@@ -7,6 +7,7 @@ HEADERS = avdevice.h                                                    \
 
 OBJS    = alldevices.o                                                  \
           avdevice.o                                                    \
+          utils.o                                                       \
 
 # input/output devices
 OBJS-$(CONFIG_ALSA_INDEV)                += alsa-audio-common.o \

libavdevice/avdevice.c

@@ -21,6 +21,7 @@
 #include "libavutil/pixfmt.h"
 #include "libavcodec/avcodec.h"
 #include "avdevice.h"
+#include "internal.h"
 #include "config.h"
 
 #include "libavutil/ffversion.h"
@@ -208,6 +209,44 @@ int avdevice_list_devices(AVFormatContext *s, AVDeviceInfoList **device_list)
     return ret;
 }
 
+static int list_devices_for_context(AVFormatContext *s, AVDictionary *options,
+                                    AVDeviceInfoList **device_list)
+{
+    AVDictionary *tmp = NULL;
+    int ret;
+
+    av_dict_copy(&tmp, options, 0);
+    if ((ret = av_opt_set_dict2(s, &tmp, AV_OPT_SEARCH_CHILDREN)) < 0)
+        goto fail;
+    ret = avdevice_list_devices(s, device_list);
+  fail:
+    av_dict_free(&tmp);
+    avformat_free_context(s);
+    return ret;
+}
+
+int avdevice_list_input_sources(AVInputFormat *device, const char *device_name,
+                                AVDictionary *device_options, AVDeviceInfoList **device_list)
+{
+    AVFormatContext *s = NULL;
+    int ret;
+
+    if ((ret = ff_alloc_input_device_context(&s, device, device_name)) < 0)
+        return ret;
+    return list_devices_for_context(s, device_options, device_list);
+}
+
+int avdevice_list_output_sinks(AVOutputFormat *device, const char *device_name,
+                               AVDictionary *device_options, AVDeviceInfoList **device_list)
+{
+    AVFormatContext *s = NULL;
+    int ret;
+
+    if ((ret = avformat_alloc_output_context2(&s, device, device_name, NULL)) < 0)
+        return ret;
+    return list_devices_for_context(s, device_options, device_list);
+}
+
 void avdevice_free_list_devices(AVDeviceInfoList **device_list)
 {
     AVDeviceInfoList *list;

libavdevice/avdevice.h

@@ -484,4 +484,26 @@ int avdevice_list_devices(struct AVFormatContext *s, AVDeviceInfoList **device_l
  */
 void avdevice_free_list_devices(AVDeviceInfoList **device_list);
 
+/**
+ * List devices.
+ *
+ * Returns available device names and their parameters.
+ * These are convinient wrappers for avdevice_list_devices().
+ * Device context is allocated and deallocated internally.
+ *
+ * @param device           device format. May be NULL if device name is set.
+ * @param device_name      device name. May be NULL if device format is set.
+ * @param device_options   An AVDictionary filled with device-private options. May be NULL.
+ *                         The same options must be passed later to avformat_write_header() for output
+ *                         devices or avformat_open_input() for input devices, or at any other place
+ *                         that affects device-private options.
+ * @param[out] device_list list of autodetected devices
+ * @return count of autodetected devices, negative on error.
+ * @note device argument takes precedence over device_name when both are set.
+ */
+int avdevice_list_input_sources(struct AVInputFormat *device, const char *device_name,
+                                AVDictionary *device_options, AVDeviceInfoList **device_list);
+int avdevice_list_output_sinks(struct AVOutputFormat *device, const char *device_name,
+                               AVDictionary *device_options, AVDeviceInfoList **device_list);
+
 #endif /* AVDEVICE_AVDEVICE_H */

libavdevice/internal.h

@@ -0,0 +1,27 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVDEVICE_INTERNAL_H
+#define AVDEVICE_INTERNAL_H
+
+#include "libavformat/avformat.h"
+
+int ff_alloc_input_device_context(struct AVFormatContext **avctx, struct AVInputFormat *iformat,
+                                  const char *format);
+
+#endif

libavdevice/utils.c

@@ -0,0 +1,59 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "internal.h"
+#include "libavutil/opt.h"
+#include "libavformat/avformat.h"
+
+int ff_alloc_input_device_context(AVFormatContext **avctx, AVInputFormat *iformat, const char *format)
+{
+    AVFormatContext *s;
+    int ret = 0;
+
+    *avctx = NULL;
+    if (!iformat && !format)
+        return AVERROR(EINVAL);
+    if (!(s = avformat_alloc_context()))
+        return AVERROR(ENOMEM);
+
+    if (!iformat)
+        iformat = av_find_input_format(format);
+    if (!iformat || !iformat->priv_class || !AV_IS_INPUT_DEVICE(iformat->priv_class->category)) {
+        ret = AVERROR(EINVAL);
+        goto error;
+    }
+    s->iformat = iformat;
+    if (s->iformat->priv_data_size > 0) {
+        s->priv_data = av_mallocz(s->iformat->priv_data_size);
+        if (!s->priv_data) {
+            ret = AVERROR(ENOMEM);
+            goto error;
+        }
+        if (s->iformat->priv_class) {
+            *(const AVClass**)s->priv_data= s->iformat->priv_class;
+            av_opt_set_defaults(s->priv_data);
+        }
+    } else
+        s->priv_data = NULL;
+
+    *avctx = s;
+    return 0;
+  error:
+    avformat_free_context(s);
+    return ret;
+}

libavdevice/version.h

@@ -28,7 +28,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVDEVICE_VERSION_MAJOR 56
-#define LIBAVDEVICE_VERSION_MINOR  3
+#define LIBAVDEVICE_VERSION_MINOR  4
 #define LIBAVDEVICE_VERSION_MICRO 100
 
 #define LIBAVDEVICE_VERSION_INT AV_VERSION_INT(LIBAVDEVICE_VERSION_MAJOR, \