gst_sample_set_buffer
时间: 2024-06-02 21:05:35 浏览: 25
`gst_sample_set_buffer`是GStreamer中用于设置采样数据缓冲区的函数。它可以将缓冲区数据与样本(sample)相关联,以便于在管道中传递和处理数据。一般情况下,我们可以通过调用`gst_buffer_new_allocate`或者`gst_buffer_new_wrapped`来创建一个新的缓冲区,然后使用`gst_sample_set_buffer`将缓冲区与样本相关联。当然,在使用该函数之前,我们需要确保已经创建了一个有效的GstSample对象。
相关问题
C语言调用GStreamer把图像数据编码为jpg怎么写
在C语言中使用GStreamer将图像数据编码为JPEG格式的步骤如下:
1. 导入必要的头文件和库文件:
```c
#include <gst/gst.h>
#include <stdio.h>
/* 编译时需要使用`pkg-config --cflags --libs gstreamer-1.0`命令获取相应的编译选项 */
```
2. 创建GStreamer管道:
```c
GstElement *pipeline;
pipeline = gst_pipeline_new("image-pipeline");
```
3. 创建GStreamer元素:
```c
GstElement *jpegenc, *appsink;
jpegenc = gst_element_factory_make("jpegenc", "jpeg-encoder");
appsink = gst_element_factory_make("appsink", "app-sink");
```
4. 设置元素属性:
```c
g_object_set(G_OBJECT(jpegenc), "quality", 80, NULL);
```
5. 将元素添加到管道中:
```c
gst_bin_add_many(GST_BIN(pipeline), appsink, jpegenc, NULL);
```
6. 设置管道状态为“播放”:
```c
gst_element_set_state(pipeline, GST_STATE_PLAYING);
```
7. 将图像数据传递给元素:
```c
GstBuffer *buffer;
// 假设img_data为图像数据,img_size为图像数据的大小
buffer = gst_buffer_new_allocate(NULL, img_size, NULL);
gst_buffer_fill(buffer, 0, img_data, img_size);
g_object_set(G_OBJECT(appsink), "emit-signals", TRUE, "sync", FALSE, NULL);
g_signal_connect(appsink, "new-sample", G_CALLBACK(on_new_sample), buffer);
```
8. 定义新样本回调函数:
```c
GstFlowReturn on_new_sample(GstElement *sink, gpointer data) {
GstSample *sample;
GstBuffer *buffer;
GstMapInfo map;
buffer = (GstBuffer *)data;
sample = gst_sample_new(buffer, NULL, NULL, NULL);
gst_buffer_map(buffer, &map, GST_MAP_READ);
// 将JPEG数据写入文件中
FILE *fp = fopen("image.jpg", "wb");
fwrite(map.data, map.size, 1, fp);
fclose(fp);
gst_buffer_unmap(buffer, &map);
gst_sample_unref(sample);
return GST_FLOW_OK;
}
```
9. 释放资源:
```c
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(GST_OBJECT(pipeline));
```
完整的代码如下:
```c
#include <gst/gst.h>
#include <stdio.h>
GstFlowReturn on_new_sample(GstElement *sink, gpointer data);
int main(int argc, char *argv[]) {
GstElement *pipeline, *jpegenc, *appsink;
GstBuffer *buffer;
GstMapInfo map;
guint8 *img_data; // 图像数据
guint img_size; // 图像数据大小
/* 初始化GStreamer */
gst_init(&argc, &argv);
/* 创建GStreamer管道 */
pipeline = gst_pipeline_new("image-pipeline");
/* 创建GStreamer元素 */
jpegenc = gst_element_factory_make("jpegenc", "jpeg-encoder");
appsink = gst_element_factory_make("appsink", "app-sink");
/* 设置元素属性 */
g_object_set(G_OBJECT(jpegenc), "quality", 80, NULL);
/* 将元素添加到管道中 */
gst_bin_add_many(GST_BIN(pipeline), appsink, jpegenc, NULL);
/* 将管道设置为“播放”状态 */
gst_element_set_state(pipeline, GST_STATE_PLAYING);
/* 将图像数据传递给元素 */
buffer = gst_buffer_new_allocate(NULL, img_size, NULL);
gst_buffer_fill(buffer, 0, img_data, img_size);
g_object_set(G_OBJECT(appsink), "emit-signals", TRUE, "sync", FALSE, NULL);
g_signal_connect(appsink, "new-sample", G_CALLBACK(on_new_sample), buffer);
/* 等待图像编码完成 */
getchar();
/* 释放资源 */
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(GST_OBJECT(pipeline));
return 0;
}
GstFlowReturn on_new_sample(GstElement *sink, gpointer data) {
GstSample *sample;
GstBuffer *buffer;
GstMapInfo map;
buffer = (GstBuffer *)data;
sample = gst_sample_new(buffer, NULL, NULL, NULL);
gst_buffer_map(buffer, &map, GST_MAP_READ);
/* 将JPEG数据写入文件中 */
FILE *fp = fopen("image.jpg", "wb");
fwrite(map.data, map.size, 1, fp);
fclose(fp);
gst_buffer_unmap(buffer, &map);
gst_sample_unref(sample);
return GST_FLOW_OK;
}
```
其中,img_data和img_size需要根据实际的图像数据进行设置。
gstreamer获取h264码流中SPS和PPS信息的方法 举个C语言例子
以下是使用 C 语言的 GStreamer API 获取 H264 码流中 SPS 和 PPS 信息的示例代码:
```c
#include <gst/gst.h>
int main(int argc, char *argv[]) {
GstElement *pipeline, *src, *h264parse, *capsfilter, *splitter, *queue_sps, *queue_pps, *sink;
GstBus *bus;
GstMessage *msg;
GstCaps *caps;
GstBuffer *buf;
gboolean ret;
GError *err = NULL;
guint8 *sps_data = NULL, *pps_data = NULL;
gsize sps_size = 0, pps_size = 0;
/* Initialize GStreamer */
gst_init(&argc, &argv);
/* Create elements */
pipeline = gst_pipeline_new("pipeline");
src = gst_element_factory_make("filesrc", "src");
h264parse = gst_element_factory_make("h264parse", "parse");
capsfilter = gst_element_factory_make("capsfilter", "caps");
splitter = gst_element_factory_make("splitter", "split");
queue_sps = gst_element_factory_make("queue", "sps");
queue_pps = gst_element_factory_make("queue", "pps");
sink = gst_element_factory_make("fakesink", "sink");
/* Set properties */
g_object_set(G_OBJECT(src), "location", "test.h264", NULL);
caps = gst_caps_from_string("video/x-h264, stream-format=byte-stream");
g_object_set(G_OBJECT(capsfilter), "caps", caps, NULL);
/* Build the pipeline */
gst_bin_add_many(GST_BIN(pipeline), src, h264parse, capsfilter, splitter, queue_sps, queue_pps, sink, NULL);
gst_element_link_many(src, h264parse, capsfilter, splitter, NULL);
gst_element_link_many(splitter, queue_sps, sink, NULL);
gst_element_link_many(splitter, queue_pps, sink, NULL);
/* Start playing */
ret = gst_element_set_state(pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE) {
g_printerr("Failed to start pipeline\n");
return -1;
}
/* Wait until error or state change */
bus = gst_element_get_bus(pipeline);
msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE, GST_MESSAGE_ERROR | GST_MESSAGE_STATE_CHANGED);
if (msg != NULL) {
gst_message_unref(msg);
}
/* Get SPS and PPS data */
while (sps_data == NULL || pps_data == NULL) {
GstSample *sample;
GstBuffer *buf;
sample = gst_app_sink_pull_sample(GST_APP_SINK(queue_sps));
if (sample != NULL) {
buf = gst_sample_get_buffer(sample);
sps_data = gst_buffer_extract_dup(buf, 0, gst_buffer_get_size(buf), &err);
sps_size = gst_buffer_get_size(buf);
gst_sample_unref(sample);
}
sample = gst_app_sink_pull_sample(GST_APP_SINK(queue_pps));
if (sample != NULL) {
buf = gst_sample_get_buffer(sample);
pps_data = gst_buffer_extract_dup(buf, 0, gst_buffer_get_size(buf), &err);
pps_size = gst_buffer_get_size(buf);
gst_sample_unref(sample);
}
}
/* Output SPS and PPS data */
g_print("SPS:");
for (int i = 0; i < sps_size; i++) {
g_print(" %02x", sps_data[i]);
}
g_print("\n");
g_print("PPS:");
for (int i = 0; i < pps_size; i++) {
g_print(" %02x", pps_data[i]);
}
g_print("\n");
/* Stop playing */
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(pipeline);
return 0;
}
```
这段代码与前面的 Python 代码类似,使用了 `h264parse` 元素将 H264 码流解析为 NAL 单元,使用 `capsfilter` 元素设置媒体格式,并使用 `splitter` 元素将 NAL 单元分离为 SPS、PPS 和 IDR 帧等单元。不同之处在于,这里使用了 `gst_app_sink_pull_sample()` 方法从队列中获取数据。由于 C 语言没有 Python 中的 `bytearray` 类型,所以这里使用了 `guint8 *` 类型的指针来保存 SPS 和 PPS 数据,并使用 `gsize` 类型的变量保存数据的大小。