我在将视频流从树莓派解码到带有 Qt GUI 的笔记本电脑时遇到问题。
我的 pi 管道是(使用 adafruit raspberry pi 相机):
raspivid -t 999999 -h 480 -w 640 -fps 25 -hf -b 2000000 -o - | gst-launch-1.0 -v fdsrc ! h264parse ! rtph264pay config-interval=1 pt=96 ! gdppay ! tcpserversink host=10.0.0.128 port=5000
只需使用带有管道的笔记本电脑上的查看器:
gst-launch-1.0 -v tcpclientsrc host=10.0.0.128 port=5000 ! gdpdepay ! rtph264depay ! avdec_h264 ! videoconvert ! autovideosink sync=false
以相当不错的速率提供非常漂亮的彩色视频,尽管我没有测量帧速率。
当我在我的 GUI 应用程序中使用 qtgstreamer 时(源宽度 = 640,高度 = 480,并且我假设一个 8 位 RGB 图像)我在下面的代码中得到缓冲区大小 460800,我希望它是 921600。如果我使用 QImage::Format_RGB888 程序会因为图像缓冲区太小而崩溃。如果我使用 QImage::Format_Index8 它将运行良好,在我的 GUI 中显示视频,并且除了黑白之外的所有内容。有人有想法么?这是我的相关代码:
bool CameraStreamer::initStreamer()
{
gst_init (NULL, NULL);
//gst-launch-1.0 -v tcpclientsrc host=10.0.0.128 port=5000 ! gdpdepay ! rtph264depay ! avdec_h264 ! videoconvert ! autovideosink sync=false
pipeline = gst_pipeline_new("Camera");
source = gst_element_factory_make ("tcpclientsrc", "cam-source");
depay = gst_element_factory_make("gdpdepay", "depay");
rtpdepay = gst_element_factory_make("rtph264depay","rtp-depay");
decoder = gst_element_factory_make ("avdec_h264", "videodecoder");
videoconvert = gst_element_factory_make("videoconvert","video-convert");
sink = gst_element_factory_make ("appsink", "video-output");
if (!pipeline || !source || !depay || !rtpdepay || !decoder || !videoconvert || !sink ) {
qDebug() << "One element could not be created. Exiting.\n";
return false;
}
callbacks.eos = NULL;
callbacks.new_sample = newBufferCallback;
callbacks.new_preroll = NULL;
gst_app_sink_set_callbacks((GstAppSink *) sink, &callbacks, this, NULL);
g_object_set (G_OBJECT(source), "port", 5001, NULL);
g_object_set (G_OBJECT(source),"host","10.0.0.128",NULL);
gst_bin_add_many (GST_BIN (pipeline),
source, depay,rtpdepay,decoder, videoconvert,sink, NULL);
if (!gst_element_link_many (source, depay,rtpdepay,decoder, videoconvert,sink, NULL))
g_warning ("Main pipeline link Fail...");
ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);
if (ret == GST_STATE_CHANGE_FAILURE)
{
g_printerr ("Unable to set the pipeline to the playing state.");
gst_object_unref (pipeline);
return false;
}
return true;
}
GstFlowReturn CameraStreamer::newBufferCallback(GstAppSink *app_sink, void *obj)
{
if(app_sink == NULL)
{
qDebug() << "app_sink is NULL";
return GST_FLOW_ERROR;
}
GstSample* sample = gst_app_sink_pull_sample(app_sink);
if(!sample)
{
qDebug() << "Error retreiving buffer...";
return GST_FLOW_ERROR;
}
GstCaps* caps = gst_sample_get_caps (sample);
if (!caps) {
qDebug() << "could not get snapshot format\n";
exit (-1);
}
gint width, height;
GstStructure* s = gst_caps_get_structure (caps, 0);
int res = gst_structure_get_int (s, "width", &width)
| gst_structure_get_int (s, "height", &height);
if (!res) {
qDebug() << "could not get snapshot dimension\n";
exit (-1);
}
GstMapInfo map;
GstBuffer *buffer = gst_sample_get_buffer (sample);
qDebug() << "size: " << gst_buffer_get_size(buffer);
gst_buffer_map (buffer, &map, GST_MAP_READ);
QImage img(map.data,width,height, QImage::Format_RGB888);
img = img.copy();
((CameraStreamer*)obj)->emitNewImage(img);
gst_buffer_unmap (buffer, &map);
gst_sample_unref (sample);
return GST_FLOW_OK;
}