[FFmpeg-devel] [PATCH v3 31/34] doc/examples: adding device_get_capabilities example
Diederick Niehorster
dcnieho at gmail.com
Tue Jul 6 12:20:17 EEST 2021
This example also shows use of get_device_list API.
Also improve capability API doc in avdevice.h: now point to this example
instead of rough example code given in the header.
Signed-off-by: Diederick Niehorster <dcnieho at gmail.com>
---
configure | 2 +
doc/examples/.gitignore | 1 +
doc/examples/Makefile | 1 +
doc/examples/Makefile.example | 1 +
doc/examples/device_get_capabilities.c | 243 +++++++++++++++++++++++++
libavdevice/avdevice.h | 33 +---
6 files changed, 249 insertions(+), 32 deletions(-)
create mode 100644 doc/examples/device_get_capabilities.c
diff --git a/configure b/configure
index b124411609..ab5d6fee30 100755
--- a/configure
+++ b/configure
@@ -1706,6 +1706,7 @@ EXAMPLE_LIST="
decode_audio_example
decode_video_example
demuxing_decoding_example
+ device_get_capabilities_example
encode_audio_example
encode_video_example
extract_mvs_example
@@ -3716,6 +3717,7 @@ avio_reading_deps="avformat avcodec avutil"
decode_audio_example_deps="avcodec avutil"
decode_video_example_deps="avcodec avutil"
demuxing_decoding_example_deps="avcodec avformat avutil"
+device_get_capabilities_example_deps="avdevice avformat avutil"
encode_audio_example_deps="avcodec avutil"
encode_video_example_deps="avcodec avutil"
extract_mvs_example_deps="avcodec avformat avutil"
diff --git a/doc/examples/.gitignore b/doc/examples/.gitignore
index 44960e1de7..256f33a600 100644
--- a/doc/examples/.gitignore
+++ b/doc/examples/.gitignore
@@ -3,6 +3,7 @@
/decode_audio
/decode_video
/demuxing_decoding
+/device_get_capabilities
/encode_audio
/encode_video
/extract_mvs
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index 81bfd34d5d..de707bb3ca 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -3,6 +3,7 @@ EXAMPLES-$(CONFIG_AVIO_READING_EXAMPLE) += avio_reading
EXAMPLES-$(CONFIG_DECODE_AUDIO_EXAMPLE) += decode_audio
EXAMPLES-$(CONFIG_DECODE_VIDEO_EXAMPLE) += decode_video
EXAMPLES-$(CONFIG_DEMUXING_DECODING_EXAMPLE) += demuxing_decoding
+EXAMPLES-$(CONFIG_DEVICE_GET_CAPABILITIES_EXAMPLE) += device_get_capabilities
EXAMPLES-$(CONFIG_ENCODE_AUDIO_EXAMPLE) += encode_audio
EXAMPLES-$(CONFIG_ENCODE_VIDEO_EXAMPLE) += encode_video
EXAMPLES-$(CONFIG_EXTRACT_MVS_EXAMPLE) += extract_mvs
diff --git a/doc/examples/Makefile.example b/doc/examples/Makefile.example
index a232d97f98..b861b9cc74 100644
--- a/doc/examples/Makefile.example
+++ b/doc/examples/Makefile.example
@@ -16,6 +16,7 @@ EXAMPLES= avio_list_dir \
decode_audio \
decode_video \
demuxing_decoding \
+ device_get_capabilities \
encode_audio \
encode_video \
extract_mvs \
diff --git a/doc/examples/device_get_capabilities.c b/doc/examples/device_get_capabilities.c
new file mode 100644
index 0000000000..45eb2eadf4
--- /dev/null
+++ b/doc/examples/device_get_capabilities.c
@@ -0,0 +1,243 @@
+/*
+ * Copyright (c) 2021 Diederick Niehorster
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/**
+ * @file
+ * avdevice getting capabilities example.
+ *
+ * Shows how to use the avdevice capabilities API to probe
+ * device capabilities (supported codecs, pixel formats, sample
+ * formats, resolutions, channel counts, etc)
+ * @example device_get_capabilities.c
+ */
+
+#include <libavformat/avformat.h>
+#include <libavdevice/avdevice.h>
+#include <libavutil/avstring.h>
+#include <libavutil/log.h>
+#include <libavutil/bprint.h>
+
+int print_option_ranges(enum AVOptionType type, AVOptionRanges *ranges)
+{
+ for (int range_index = 0; range_index < ranges->nb_ranges; range_index++) {
+ int ret;
+ char *out_val = NULL;
+ AVBPrint bp;
+ av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
+ for (int component_index = 0; component_index < ranges->nb_components; component_index++)
+ {
+ AVOptionRange* range = ranges->range[ranges->nb_ranges * component_index + range_index];
+ if (component_index > 0)
+ av_bprintf(&bp, ", ");
+ av_bprintf(&bp, "%s: ", range->str);
+ if (range->value_min > range->value_max)
+ av_bprintf(&bp, "<value not available>");
+ else {
+ avdevice_capabilities_bprint_num(&bp, range->str, range->value_min);
+ if (range->is_range) {
+ av_bprintf(&bp, " -- ");
+ avdevice_capabilities_bprint_num(&bp, range->str, range->value_max);
+ }
+ }
+ }
+ if (!av_bprint_is_complete(&bp))
+ return AVERROR(ENOMEM);
+ if ((ret = av_bprint_finalize(&bp, &out_val)) < 0)
+ return ret;
+ printf("%s\n", out_val);
+ av_freep(&out_val);
+ }
+
+ return 0;
+}
+
+void list_queries()
+{
+ const AVOption *opt = NULL;
+ const AVClass *class = avdevice_capabilities_get_class();
+ while (opt = av_opt_next(&class, opt))
+ fprintf(stderr, " %s\n", opt->name);
+}
+
+void list_device_sources(const AVInputFormat *fmt)
+{
+ int ret;
+ AVDeviceInfoList *device_list = NULL;
+
+ if (!fmt || !fmt->priv_class || !AV_IS_INPUT_DEVICE(fmt->priv_class->category))
+ return;
+
+ if (!fmt->get_device_list) {
+ ret = AVERROR(ENOSYS);
+ fprintf(stderr, " Cannot list sources. Not implemented.\n");
+ return;
+ }
+
+ if ((ret = avdevice_list_input_sources(fmt, NULL, NULL, &device_list)) < 0) {
+ fprintf(stderr, " Cannot list sources.\n");
+ return;
+ }
+
+ for (int i = 0; i < device_list->nb_devices; i++) {
+ const AVDeviceInfo *device = device_list->devices[i];
+ fprintf(stderr, " %s %s (", device_list->default_device == i ? "*" : " ", device->device_name);
+ if (device->nb_media_types > 0 && device->media_types) {
+ for (int j = 0; j < device->nb_media_types; ++j) {
+ const char* media_type = av_get_media_type_string(device->media_types[j]);
+ if (j > 0)
+ fprintf(stderr, ", ");
+ fprintf(stderr, "%s", media_type ? media_type : "unknown");
+ }
+ }
+ else {
+ fprintf(stderr, "none");
+ }
+ fprintf(stderr, ")\n");
+ }
+
+ avdevice_free_list_devices(&device_list);
+}
+
+
+
+int main (int argc, char **argv)
+{
+ int ret = 0;
+ const char *device_name = NULL;
+ const char *input_name = NULL;
+ const char *query_cap = NULL;
+ const char *set_cap_name = NULL;
+ const char *set_cap_value = NULL;
+
+ const AVInputFormat *fmt = NULL;
+ AVFormatContext *fmt_ctx = NULL;
+ AVDeviceCapabilitiesQuery *caps = NULL;
+ AVOptionRanges *ranges = NULL;
+ const AVOption *opt = NULL;
+
+ if (argc != 6) {
+ fprintf(stderr, "usage: %s device_name input_name query_cap set_cap_name set_cap_value\n"
+ "API example program to show how to use the avdevice\n"
+ "capabilities API to probe device capabilities \n"
+ "(supported codecs, pixel formats, sample formats,\n"
+ "resolutions, channel counts, etc).\n\n"
+ "example invocation: "
+ "%s dshow video=\"Integrated Webcam\" frame_size pixel_format yuyv422",
+ argv[0], argv[0]);
+ exit(1);
+ }
+ device_name = argv[1];
+ input_name = argv[2];
+ query_cap = argv[3];
+ set_cap_name = argv[4];
+ set_cap_value = argv[5];
+
+ // make sure avdevices can be found among input and output formats
+ avdevice_register_all();
+ // find specified device
+ fmt = av_find_input_format(device_name);
+ if (!fmt) {
+ fprintf(stderr, "Could not find the device '%s'\n",device_name);
+ ret = AVERROR(EINVAL);
+ goto end;
+ }
+
+ // prepare device format context, and set device to query,
+ ret = avformat_alloc_input_context(&fmt_ctx, fmt, NULL);
+ if (ret < 0) {
+ fprintf(stderr, "Cannot allocate input format context\n");
+ goto end;
+ }
+ fmt_ctx->url = av_strdup(input_name);
+
+ // prepare query object, setting device options
+ ret = avdevice_capabilities_create(&caps, fmt_ctx, NULL);
+ if (ret < 0) {
+ fprintf(stderr, "avdevice_capabilities_create() failed. Possibly the input name you specified ('%s') is not available for this device ('%s').\n%s can access the following sources:\n", input_name, device_name, device_name);
+ list_device_sources(fmt);
+ goto end;
+ }
+
+ // check capability to query, and get info about the return type
+ opt = av_opt_find(caps, query_cap, NULL, 0, 0);
+ if (!opt) {
+ fprintf(stderr, "Capability '%s' you wish to query is not available.\nYou can query the following capabilities:\n", query_cap);
+ list_queries();
+ ret = AVERROR_OPTION_NOT_FOUND;
+ goto end;
+ }
+
+ // query the capability without any filter set
+ ret = av_opt_query_ranges(&ranges, caps, opt->name, AV_OPT_MULTI_COMPONENT_RANGE);
+ if (ret < 0) {
+ fprintf(stderr, "av_opt_query_ranges() failed\n");
+ goto end;
+ }
+
+ // print results
+ ret = print_option_ranges(opt->type, ranges);
+ if (ret < 0) {
+ fprintf(stderr, "printing the AVOptionRanges failed\n");
+ goto end;
+ }
+ av_opt_freep_ranges(&ranges);
+
+ printf("=============\n");
+
+ // set one capability, which may filter out some returned capabilities
+ // (or all, if set to an invalid value)
+ ret = av_opt_set(caps, set_cap_name, set_cap_value, 0);
+ if (ret < 0) {
+ fprintf(stderr, "av_opt_set() failed when trying to set the capability '%s'. Possibly it is not available.\nYou can set the following capabilities:\n", set_cap_name);
+ list_queries();
+ goto end;
+ }
+
+ // query again
+ ret = av_opt_query_ranges(&ranges, caps, opt->name, AV_OPT_MULTI_COMPONENT_RANGE);
+ if (ret < 0) {
+ fprintf(stderr, "av_opt_query_ranges() failed\n");
+ goto end;
+ }
+
+ // print results
+ print_option_ranges(opt->type, ranges);
+
+
+end:
+ if (ranges)
+ av_opt_freep_ranges(&ranges);
+ if (caps)
+ avdevice_capabilities_free(&caps, fmt_ctx);
+
+ if (fmt_ctx)
+ avformat_free_context(fmt_ctx);
+
+ if (ret < 0) {
+ char a[AV_ERROR_MAX_STRING_SIZE] = { 0 };
+ av_make_error_string(a, AV_ERROR_MAX_STRING_SIZE, ret);
+
+ printf("Error: %s\n", a);
+ }
+
+ return ret < 0;
+}
diff --git a/libavdevice/avdevice.h b/libavdevice/avdevice.h
index 11d1a6ae12..67572db992 100644
--- a/libavdevice/avdevice.h
+++ b/libavdevice/avdevice.h
@@ -368,38 +368,7 @@ int avdevice_dev_to_app_control_message(struct AVFormatContext *s,
* 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
+ * @see examples/device_get_capabilities.c
*/
typedef struct AVDeviceCapabilitiesQuery AVDeviceCapabilitiesQuery;
--
2.28.0.windows.1
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