tutorial5.c

Tutorial - Part 5: Capturing Video Frames

/*
  [title]
  \ref page_tutorial5
  [title]
 */
/* [code] */
#include <spa/param/video/format-utils.h>
#include <spa/debug/types.h>
#include <spa/param/video/type-info.h>
 
#include <pipewire/pipewire.h>
 
struct data {
        struct pw_main_loop *loop;
        struct pw_stream *stream;
 
        struct spa_video_info format;
};
 
/* [on_process] */
static void on_process(void *userdata)
{
        struct data *data = userdata;
        struct pw_buffer *b;
        struct spa_buffer *buf;
 
        if ((b = pw_stream_dequeue_buffer(data->stream)) == NULL) {
                pw_log_warn("out of buffers: %m");
                return;
        }
 
        buf = b->buffer;
        if (buf->datas[0].data == NULL)
                return;
 
        printf("got a frame of size %d\n", buf->datas[0].chunk->size);
 
        pw_stream_queue_buffer(data->stream, b);
}
/* [on_process] */
 
static void on_param_changed(void *userdata, uint32_t id, const struct spa_pod *param)
{
        struct data *data = userdata;
 
        if (param == NULL || id != SPA_PARAM_Format)
                return;
 
        if (spa_format_parse(param,
                        &data->format.media_type,
                        &data->format.media_subtype) < 0)
                return;
 
        if (data->format.media_type != SPA_MEDIA_TYPE_video ||
            data->format.media_subtype != SPA_MEDIA_SUBTYPE_raw)
                return;
 
        if (spa_format_video_raw_parse(param, &data->format.info.raw) < 0)
                return;
 
        printf("got video format:\n");
        printf("  format: %d (%s)\n", data->format.info.raw.format,
                        spa_debug_type_find_name(spa_type_video_format,
                                data->format.info.raw.format));
        printf("  size: %dx%d\n", data->format.info.raw.size.width,
                        data->format.info.raw.size.height);
        printf("  framerate: %d/%d\n", data->format.info.raw.framerate.num,
                        data->format.info.raw.framerate.denom);
 
}
 
static const struct pw_stream_events stream_events = {
        PW_VERSION_STREAM_EVENTS,
        .param_changed = on_param_changed,
        .process = on_process,
};
 
int main(int argc, char *argv[])
{
        struct data data = { 0, };
        const struct spa_pod *params[1];
        uint8_t buffer[1024];
        struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
        struct pw_properties *props;
 
        pw_init(&argc, &argv);
 
        data.loop = pw_main_loop_new(NULL);
 
        props = pw_properties_new(PW_KEY_MEDIA_TYPE, "Video",
                        PW_KEY_MEDIA_CATEGORY, "Capture",
                        PW_KEY_MEDIA_ROLE, "Camera",
                        NULL);
        if (argc > 1)
                pw_properties_set(props, PW_KEY_TARGET_OBJECT, argv[1]);
 
        data.stream = pw_stream_new_simple(
                        pw_main_loop_get_loop(data.loop),
                        "video-capture",
                        props,
                        &stream_events,
                        &data);
 
        params[0] = spa_pod_builder_add_object(&b,
                SPA_TYPE_OBJECT_Format, SPA_PARAM_EnumFormat,
                SPA_FORMAT_mediaType,       SPA_POD_Id(SPA_MEDIA_TYPE_video),
                SPA_FORMAT_mediaSubtype,    SPA_POD_Id(SPA_MEDIA_SUBTYPE_raw),
                SPA_FORMAT_VIDEO_format,    SPA_POD_CHOICE_ENUM_Id(7,
                                                SPA_VIDEO_FORMAT_RGB,
                                                SPA_VIDEO_FORMAT_RGB,
                                                SPA_VIDEO_FORMAT_RGBA,
                                                SPA_VIDEO_FORMAT_RGBx,
                                                SPA_VIDEO_FORMAT_BGRx,
                                                SPA_VIDEO_FORMAT_YUY2,
                                                SPA_VIDEO_FORMAT_I420),
                SPA_FORMAT_VIDEO_size,      SPA_POD_CHOICE_RANGE_Rectangle(
                                                &SPA_RECTANGLE(320, 240),
                                                &SPA_RECTANGLE(1, 1),
                                                &SPA_RECTANGLE(4096, 4096)),
                SPA_FORMAT_VIDEO_framerate, SPA_POD_CHOICE_RANGE_Fraction(
                                                &SPA_FRACTION(25, 1),
                                                &SPA_FRACTION(0, 1),
                                                &SPA_FRACTION(1000, 1)));
 
        pw_stream_connect(data.stream,
                          PW_DIRECTION_INPUT,
                          PW_ID_ANY,
                          PW_STREAM_FLAG_AUTOCONNECT |
                          PW_STREAM_FLAG_MAP_BUFFERS,
                          params, 1);
 
        pw_main_loop_run(data.loop);
 
        pw_stream_destroy(data.stream);
        pw_main_loop_destroy(data.loop);
 
        return 0;
}
/* [code] */