ios - 使用 iOS 从 gstreamer 中运行的管道获取快照

Question

我正在尝试从 iOS 中正在运行的管道创建快照。我使用按钮拍摄快照。

我有以下管道

udpsrc auto-multicast=true address=224.1.1.1 port=5004"
+ " ! application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z0JAH6aAQAYZAA\\,aM4wpIAA\", payload=(int)96, ssrc=(uint)19088743, timestamp-offset=(uint)0, seqnum-offset=(uint)0"
+ " ! rtpjitterbuffer latency=400"
+ " ! rtph264depay ! avdec_h264 ! videoconvert"
+ " ! tee name=snapshot snapshot. ! queue ! valve name=snap drop=true ! jpegenc ! filesink name=filepath location=screenshot.jpg async=false snapshot. ! queue"
+ " ! autovideosink

所以我在按钮中使用以下代码来处理阀门:

GstElement *element = gst_bin_get_by_name (GST_BIN (pipeline), "snap");
if (strcmp("drop", "drop") == 0)
{
    gboolean prop_val = FALSE;

    // if the property value is true, then send an EOS.
    if ( strcmp("false", "true") == 0 )
    {
        gst_element_send_event(element, gst_event_new_eos());
        prop_val = TRUE;
    } else {
        prop_val = FALSE;
    }

    g_object_set (element, "drop", prop_val, NULL);
}

但是使用这段代码我只能截图一张。而且我无法设置图像的文件名。

每次单击按钮时，如何在不阻塞流的情况下保存屏幕截图并使用自定义名称将图像保存在文档文件夹中？

Answer 1

经过长时间的搜索和斗争，我找到了解决方案，所以我会自己回答我的问题。

我已经从我的管道中删除了 T 恤，现在使用视频缓冲区的最后一个样本。

我的管道:

udpsrc auto-multicast=true address=224.1.1.1 port=5004"
+ " ! application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z0JAH6aAQAYZAA\\,aM4wpIAA\", payload=(int)96, ssrc=(uint)19088743, timestamp-offset=(uint)0, seqnum-offset=(uint)0"
+ " ! rtpjitterbuffer latency=400"
+ " ! rtph264depay ! avdec_h264 ! videoconvert"
+ " ! autovideosink

这是我的 Objective-C 代码:

-(UIImage*) takeSnapshot
{
    GstSample *videobuffer = NULL;
    GstCaps *caps;
    gint width, height;
    GstMapInfo map;

    g_object_get(G_OBJECT(video_sink), "last-sample", &videobuffer, NULL);

    if (videobuffer)
    {
        caps = gst_sample_get_caps(videobuffer);

        if (!caps) {
            return NULL;
        }

        GstStructure *s = gst_caps_get_structure(caps, 0);
        /* we need to get the final caps on the buffer to get the size */
        gboolean res;
        res = gst_structure_get_int (s, "width", &width);
        res |= gst_structure_get_int (s, "height", &height);
        if (!res) {
            return NULL;
        }

        GstBuffer *snapbuffer = gst_sample_get_buffer(videobuffer);
        if (snapbuffer && gst_buffer_map (snapbuffer, &map, GST_MAP_READ))
        {
            CGDataProviderRef provider = CGDataProviderCreateWithData(NULL,
                                                                  map.data,
                                                                  height * width * 4,
                                                                  NULL);

            CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
            CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
            CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;

            CGImageRef imageRef = CGImageCreate(width,
                                            height,
                                            8,
                                            4 * 8,
                                            width * 4,
                                            colorSpaceRef,
                                            bitmapInfo,
                                            provider,
                                            NULL,
                                            NO,
                                            renderingIntent);

            UIImage *uiImage = [UIImage imageWithCGImage:imageRef];
            CGColorSpaceRelease(colorSpaceRef);
            CGImageRelease(imageRef);

            return uiImage;
        }

        return NULL;
    }

    return NULL;
}