gstreamer怎么在代码里进行提取SPS和PPS并且保存

在 GStreamer 中，你可以使用 `GstH264Parser` 类来提取 H.264 流的 SPS 和 PPS，并将其保存到文件中。

以下是一个示例代码，展示了如何使用 `GstH264Parser` 类从 H.264 流中提取 SPS 和 PPS，并将其保存到文件中：

#include <gst/gst.h>
#include <gst/video/video.h>

int main(int argc, char *argv[]) {
    GstElement *pipeline, *source, *parser, *filter, *sink;
    GstCaps *caps;
    GstPad *src_pad, *sink_pad;
    GstBuffer *sps, *pps;
    GstH264Parser *h264parser;
    const guint8 *sps_data, *pps_data;
    guint sps_size, pps_size;
    gboolean ret;

    /* Initialize GStreamer */
    gst_init(&argc, &argv);

    /* Create elements */
    pipeline = gst_pipeline_new("pipeline");
    source = gst_element_factory_make("filesrc", "source");
    parser = gst_element_factory_make("h264parse", "parser");
    filter = gst_element_factory_make("capsfilter", "filter");
    sink = gst_element_factory_make("filesink", "sink");

    /* Set properties */
    g_object_set(G_OBJECT(source), "location", argv[1], NULL);
    g_object_set(G_OBJECT(filter), "caps", gst_caps_new_simple("video/x-h264", "stream-format", G_TYPE_STRING, "byte-stream", NULL), NULL);
    g_object_set(G_OBJECT(sink), "location", "sps_pps.bin", NULL);

    /* Add elements to the pipeline */
    gst_bin_add_many(GST_BIN(pipeline), source, parser, filter, sink, NULL);

    /* Link elements */
    if (!gst_element_link_many(source, parser, filter, sink, NULL)) {
        g_printerr("Failed to link elements\n");
        return -1;
    }

    /* Get the source pad of the parser */
    src_pad = gst_element_get_static_pad(parser, "src");

    /* Get the SPS and PPS */
    h264parser = GST_H264_PARSER(gst_h264_parser_new());
    ret = gst_pad_peer_query(src_pad, GST_QUERY_H264_SPS, 0, &sps);
    if (ret) {
        gst_h264_parser_parse_sps(h264parser, sps, &sps_data, &sps_size);
        g_print("SPS size: %d\n", sps_size);
        /* Save the SPS to file */
        fwrite(sps_data, 1, sps_size, fopen("sps.bin", "wb"));
    }
    gst_buffer_unref(sps);
    ret = gst_pad_peer_query(src_pad, GST_QUERY_H264_PPS, 0, &pps);
    if (ret) {
        gst_h264_parser_parse_pps(h264parser, pps, &pps_data, &pps_size);
        g_print("PPS size: %d\n", pps_size);
        /* Save the PPS to file */
        fwrite(pps_data, 1, pps_size, fopen("pps.bin", "wb"));
    }
    gst_buffer_unref(pps);

    /* Release resources */
    g_object_unref(h264parser);
    gst_object_unref(src_pad);
    gst_element_set_state(pipeline, GST_STATE_NULL);
    gst_object_unref(pipeline);

    return 0;
}

在上面的代码中，我们创建了 `GstH264Parser` 对象，并使用 `gst_pad_peer_query()` 函数从 parser 元素的源 pad 中获取 SPS 和 PPS。然后，我们使用 `gst_h264_parser_parse_sps()` 和 `gst_h264_parser_parse_pps()` 函数来解析 SPS 和 PPS，并将其保存到文件中。

请注意，上述示例代码仅提供了一个基本的框架，实际使用中需要根据具体的需求进行修改和完善。