# Multi-stream rtsp using Gstreamer in python code

**URL:** <https://forums.developer.nvidia.com/t/multi-stream-rtsp-using-gstreamer-in-python-code/122290>\
**Category:** DeepStream SDK\
**Created:** [May 7, 2020, 10:35am UTC](https://forums.developer.nvidia.com/t/multi-stream-rtsp-using-gstreamer-in-python-code/122290 "2020-05-07T10:35:02Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![LoveNvidia](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@LoveNvidia](https://forums.developer.nvidia.com/u/LoveNvidia)\
**Post date:** [May 7, 2020, 10:35am UTC](https://forums.developer.nvidia.com/t/multi-stream-rtsp-using-gstreamer-in-python-code/122290/1 "2020-05-07T10:35:02Z")

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Hello guys,  
I’m working on multi-stream decoder using gstreamer + opencv python code with jetson nano.  
**Q1-** I want to know, what’s best gstreamer pipeline with opencv in python code?  
I used this :

```
gstream_elemets = (
    'rtspsrc location=rtsp latency=300 !'
    'queue leaky=2 !'
    'rtph264depay !'
    'h264parse !'
    'omxh264dec enable-max-performance=1 enable-low-outbuffer=1 !'
    'video/x-raw(memory:NVMM),format=(string)NV12 !'
    'nvvidconv ! video/x-raw, width=(int)300, height=(int)300, format=(string)BGRx !'
    'videoconvert ! video/x-raw, format=(string)BGR !'
    'appsink').
cv2.VideoCapture(gstream_elemets, cv2.CAP_GSTREAMER)

```

My input frame-rate is above 20 FPS and I want the output frame rate to be under 10 FPS.

**Q1.1-** in your opinion, Is it better to use **enable-low-outbuffer=1**?  
**Q1.2 -** what’s difference using of **'videoconvert ! ’** instead of **‘videoconvert ! video/x-raw, format=(string)BGR !’**? In two case, It’s on and correctly work. I want to know, which of case have extra processing step and is time-consuming and resource-consuming?  
**Q1.3-** why we use **rtph264depay**? Is it needed in rtsp?

As you know, the opencv only supported CPU buffer, because of this, we use **videoconvert ! video/x-raw, format=(string)BGR !**.  
**Q2-** Is it possile to grap the batch of decoded streamed without opencv? I don’t know to CPU buffer to be bottleneck for me.

**Q3-** I used multi-thread python for handeling multi-stream decoding and the NVDEC of jetson nano is activated. Because my output is lower than input, I defined a dynamic programming that give me a given FPS of output, like this snnipet code: Is this way is efficient?

```
while cap.isOpened():
    frame = cap.read()[1]
    sleep(1./frame_rate_output)

```

and I used 6 streams and I runned as multi-thread and is corrctly work. my problem is in the capturing of 6 decode frames at the same time, not with for loop like this:

```
frames = []
for cam in cams
      frames.append(cam.read())

```

It’s work and ok, One thing to mention, time-consuming of this for loop is 1 ms in my opinion this value is very samll, perhapse It’s not neccesory to use multi-thread for capturing the batch of frames, right?

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**Author:** ![DaneLLL](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/danelll/32/14043_2.png) [@DaneLLL](https://forums.developer.nvidia.com/u/DaneLLL)\
**Post date:** [May 8, 2020, 1:27am UTC](https://forums.developer.nvidia.com/t/multi-stream-rtsp-using-gstreamer-in-python-code/122290/3 "2020-05-08T01:27:04Z")

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Hi,  
The information are provided and shared by other users:

> [@Multi-stream rtsp GStreamer + Opencv](https://forums.developer.nvidia.com/t/multi-stream-rtsp-gstreamer-opencv/121142/13):
>
> Opencv can work with different framerates, but you would have to set these accordingly. Decreasing framerate is not difficult. You can do both ways: Use gstreamer plugin videorate: #include \<iostream\> #include \<opencv2/core.hpp\> #include \<opencv2/highgui.hpp\> #include \<opencv2/videoio.hpp\> int main(void) { const char \*gst\_cap = "videotestsrc ! video/x-raw, format=BGR, width=1280, height=720, framerate=30/1" " ! videorate ! video/x-raw, format=BGR, framerate=…

> [@Pipeline multi-stream hardware decoder RTSP with jetson nano](https://forums.developer.nvidia.com/t/pipeline-multi-stream-hardware-decoder-rtsp-with-jetson-nano/120180):
>
> Hi guys, I want to do pipeline multi-stream decoder on jetson nano using H264 hardware decoder. when I run directly this function: def stream\_rtsp(uri, width, height, latency): gst\_str = ('rtspsrc location={} latency={} ! ’ 'rtph264depay ! h264parse ! omxh264dec ! ’ 'nvvidconv ! ’ 'video/x-raw, width=(int){}, height=(int){}, ’ 'format=(string)BGRx ! videoconvert ! ’ ‘appsink’).format(uri, latency, width, height) then I check to use NVDEC ro not with sudo tegrastats, I see NVDEC is ac…

> [@Gradualy increased memory usage when use gstreamer + opencv](https://forums.developer.nvidia.com/t/gradualy-increased-memory-usage-when-use-gstreamer-opencv/121069/17):
>
> Hi, Please check the source code in OpenCV: // we support 11 types of data: // video/x-raw, format=BGR -\> 8bit, 3 channels // video/x-raw, format=GRAY8 -\> 8bit, 1 channel // video/x-raw, format=UYVY -\> 8bit, 2 channel // video/x-raw, format=YUY2 -\> 8bit, 2 channel // video/x-raw, format=YVYU -\> 8bit, 2 channel // video/x-raw, format=NV12 -\> 8bit, 1 channel (height is 1.5x larger than true height) // video/x-raw, format=NV21 -\> …

The solution is optimal for using gstreamer + OpenCV. If you don’t need OpenCV, you may try DeepStream SDK. There are python samples:

> **[GitHub - NVIDIA-AI-IOT/deepstream\_python\_apps: DeepStream SDK Python bindings and sample...](https://github.com/NVIDIA-AI-IOT/deepstream_python_apps)**
>
> DeepStream SDK Python bindings and sample applications

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<div class="post-metadata">

**Author:** ![TomNVIDIA](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/tomnvidia/32/14181_2.png) [@TomNVIDIA](https://forums.developer.nvidia.com/u/TomNVIDIA)\
**Post date:** [October 12, 2021, 4:17pm UTC](https://forums.developer.nvidia.com/t/multi-stream-rtsp-using-gstreamer-in-python-code/122290/5 "2021-10-12T16:17:53Z")

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Closed on October 12, 2021, 4:17pm UTC