lavd: add device capabilities API

Provides API to query device capabilities.
Each device must implement callbacks to benefit from this API.

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

1 files changed, 128 insertions, 0 deletions

diff --git a/libavdevice/avdevice.h b/libavdevice/avdevice.h
index 8b78067133..e194663ee3 100644
--- a/libavdevice/avdevice.h
+++ b/libavdevice/avdevice.h
@@ -43,6 +43,9 @@
  * @}
  */
 
+#include "libavutil/log.h"
+#include "libavutil/opt.h"
+#include "libavutil/dict.h"
 #include "libavformat/avformat.h"
 
 /**
@@ -228,6 +231,131 @@ int avdevice_dev_to_app_control_message(struct AVFormatContext *s,
                                         void *data, size_t data_size);
 
 /**
+ * Following API allows user to probe device capabilities (supported codecs,
+ * pixel formats, sample formats, resolutions, channel counts, etc).
+ * It is build on top op AVOption API.
+ * Queried capabilities allows to set up converters of video or audio
+ * parameters that fit to the device.
+ *
+ * List of capablities that can be queried:
+ *  - Capabilities valid for both audio and video devices:
+ *    - codec:          supported audio/video codecs.
+ *                      type: AV_OPT_TYPE_INT (AVCodecID value)
+ *  - Capabilities valid for audio devices:
+ *    - sample_format:  supported sample formats.
+ *                      type: AV_OPT_TYPE_INT (AVSampleFormat value)
+ *    - sample_rate:    supported sample rates.
+ *                      type: AV_OPT_TYPE_INT
+ *    - channels:       supported number of channels.
+ *                      type: AV_OPT_TYPE_INT
+ *    - channel_layout: supported channel layouts.
+ *                      type: AV_OPT_TYPE_INT64
+ *  - Capabilities valid for video devices:
+ *    - pixel_format:   supported pixel formats.
+ *                      type: AV_OPT_TYPE_INT (AVPixelFormat value)
+ *    - window_size:    supported window sizes (describes size of the window size presented to the user).
+ *                      type: AV_OPT_TYPE_IMAGE_SIZE
+ *    - frame_size:     supported frame sizes (describes size of provided video frames).
+ *                      type: AV_OPT_TYPE_IMAGE_SIZE
+ *    - fps:            supported fps values
+ *                      type: AV_OPT_TYPE_RATIONAL
+ *
+ * Value of the capability may be set by user using av_opt_set() function
+ * and AVDeviceCapabilitiesQuery object. Following queries will
+ * limit results to the values matching already set capabilities.
+ * For example, setting a codec may impact number of formats or fps values
+ * returned during next query. Setting invalid value may limit results to zero.
+ *
+ * Example of the usage basing on opengl output device:
+ *
+ * @code
+ *  AVFormatContext *oc = NULL;
+ *  AVDeviceCapabilitiesQuery *caps = NULL;
+ *  AVOptionRanges *ranges;
+ *  int ret;
+ *
+ *  if ((ret = avformat_alloc_output_context2(&oc, NULL, "opengl", NULL)) < 0)
+ *      goto fail;
+ *  if (avdevice_capabilities_create(&caps, oc, NULL) < 0)
+ *      goto fail;
+ *
+ *  //query codecs
+ *  if (av_opt_query_ranges(&ranges, caps, "codec", AV_OPT_MULTI_COMPONENT_RANGE)) < 0)
+ *      goto fail;
+ *  //pick codec here and set it
+ *  av_opt_set(caps, "codec", AV_CODEC_ID_RAWVIDEO, 0);
+ *
+ *  //query format
+ *  if (av_opt_query_ranges(&ranges, caps, "pixel_format", AV_OPT_MULTI_COMPONENT_RANGE)) < 0)
+ *      goto fail;
+ *  //pick format here and set it
+ *  av_opt_set(caps, "pixel_format", AV_PIX_FMT_YUV420P, 0);
+ *
+ *  //query and set more capabilities
+ *
+ * fail:
+ *  //clean up code
+ *  avdevice_capabilities_free(&query, oc);
+ *  avformat_free_context(oc);
+ * @endcode
+ */
+
+/**
+ * Structure describes device capabilites.
+ *
+ * It is used by devices in conjuntion with av_device_capabilities AVOption table
+ * to implement capabilities probing API based on AVOption API. Should not be used directly.
+ */
+typedef struct AVDeviceCapabilitiesQuery {
+    const AVClass *class;
+    AVFormatContext *device_context;
+    enum AVCodecID codec;
+    enum AVSampleFormat sample_format;
+    enum AVPixelFormat pixel_format;
+    int sample_rate;
+    int channels;
+    int64_t channel_layout;
+    int window_width;
+    int window_height;
+    int frame_width;
+    int frame_height;
+    AVRational fps;
+} AVDeviceCapabilitiesQuery;
+
+/**
+ * AVOption table used by devices to implement device capabilites API. Should not be used by a user.
+ */
+extern const AVOption av_device_capabilities[];
+
+/**
+ * Initialize capabilities probing API based on AVOption API.
+ *
+ * avdevice_capabilities_free() must be called when query capabilities API is
+ * not used anymore.
+ *
+ * @param[out] caps      Device capabilities data. Pointer to a NULL pointer must be passed.
+ * @param s              Context of the device.
+ * @param device_options An AVDictionary filled with device-private options.
+ *                       On return this parameter will be destroyed and replaced with a dict
+ *                       containing options that were not found. 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.
+ *
+ * @return >= 0 on success, negative otherwise.
+ */
+int avdevice_capabilities_create(AVDeviceCapabilitiesQuery **caps, AVFormatContext *s,
+                                 AVDictionary **device_options);
+
+/**
+ * Free resources created by avdevice_capabilities_create()
+ *
+ * @param caps Device capabilities data to be freed.
+ * @param s    Context of the device.
+ */
+void avdevice_capabilities_free(AVDeviceCapabilitiesQuery **caps, AVFormatContext *s);
+
+/**
  * Structure describes basic parameters of the device.
  */
 typedef struct AVDeviceInfo {