# Object detection and encode with TFLite
Source: [https://docs.qualcomm.com/doc/80-70014-50/topic/single-camera-stream-with-object-detection-and-encode.html](https://docs.qualcomm.com/doc/80-70014-50/topic/single-camera-stream-with-object-detection-and-encode.html)
The use cases use a YOLOv5 TFLite model to identify the object in scene and either
overlay or compose the bounding boxes over the detected objects, and then encode this stream
as a H.264 bitstream.
## Variant 1: Use qtioverlay plugin to apply bounding box overlay
Use the following command to execute the use case:
setprop persist.overlay.use_c2d_blit 2Copy to clipboard
gst-launch-1.0 -e qtiqmmfsrc name=camsrc ! video/x-raw\(memory:GBM\),format=NV12,width=1280,height=720,framerate=30/1,compression=ubwc ! queue ! tee name=split split. ! queue ! qtimetamux name=metamux ! queue ! qtioverlay ! queue ! v4l2h264enc capture-io-mode=5 output-io-mode=5 ! h264parse ! queue ! mp4mux ! queue ! filesink location=/opt/video.mp4 split. ! queue ! qtimlvconverter ! queue ! qtimltflite delegate=external external-delegate-path=libQnnTFLiteDelegate.so external-delegate-options="QNNExternalDelegate,backend_type=htp;" model=/opt/yolov5.tflite ! queue ! qtimlvdetection threshold=75.0 results=10 module=yolov5 labels=/opt/yolov5.labels constants="YoloV5,q-offsets=<3.0>,q-scales=<0.005047998391091824>;" ! text/x-raw ! queue ! metamux.Copy to clipboard
To stop the use case, press CTRL + C.
Figure : Pipeline for bounding box overlay and encode

The figure shows the flow of the use case execution:
1. Identify object scenes from a video stream, which is coming through a camera
source.
2. Overlay bounding boxes over the detected objects using overlaylib.
3. Encode this stream as a H.264 bitstream.
4. Multiplex the stream in a MP4 container and stored as a MP4 file.
The table provides the sequential processing stages of the pipeline execution:
| Process | Description |
| --- | --- |
| [qtiqmmfsrc](https://docs.qualcomm.com/doc/80-70014-50/topic/qtiqmmfsrc.html) |
- Collects the video stream (source) and creates two copies of
the source:
- One stream is sent to qtimetamux plugin to retain
the video stream.
- The other stream is sent to a ML inferencing
pipeline.
|
| **Preprocessing** | **Preprocessing** |
| [qtimlvconverter](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimlvconverter.html) |
- Receives the video stream on its sink pad.
- Performs preprocessing:
- Color conversion
- Scaling down/up
- Normalization on the stream data when model expects
floating point values as input
- Converts the video stream to a tensor stream on its source
pad.The object detection model uses this tensor
stream for inferencing.
|
| **Inferencing** | **Inferencing** |
| [qtimltflite](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimltflite.html) |
- Loads the object detection model.
- Modifies the graph for the chosen delegate.
- Receives the tensor stream on its sinkpad.
- Executes the inference and produces tensor stream with the
object detection results on its source pad.
|
| **Postprocessing** | **Postprocessing** |
| [qtimlvdetection](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimlvdetection.html) |
- Receives the inference tensors from the object detection
model.
- Converts the inference tensors on its sinkpad into formats
like video or text that the multimedia plugins can process
later.
- Applies the threshold to the chosen number of results.
- Loads the corresponding modules for detection models.
In
this use case, qtimlvdetection does the following:
- Loads the YOLOv5 submodule.
- Produces results as structures of text.
- Sends them to sinkpad of qtimetamux.
|
| [qtimetamux](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimetamux.html) |
- Receives video stream and text stream with bounding box
results corresponding to the video stream on its
sinkpads.
- Produces GST buffers with contents of video stream from its
sink pad.
- Adds bounding boxes as GstVideoRegionOfInterest from data
sinkpad to GST buffers meta (meta muxing) on its source
pad.
|
| [qtioverlay](https://docs.qualcomm.com/doc/80-70014-50/topic/qtioverlay.html) |
- Receives the multiplexed stream.
- Overlays the bounding boxes on the VideoFrame using CL.
- Produces GST buffers with overlays in its source pad.
|
| [v4l2h264enc](https://docs.qualcomm.com/doc/80-70014-50/topic/v4l2h264enc.html) |
- Applies parameters to each frame of the video stream its
receiving on its sinkpad.
- Encodes it into bitstream and sends it over its
sourcepad.
|
| h264parse | Adds additional information corresponding to the bitstream to
GStreamer buffer meta. |
| mp4mux | Receives these buffers and creates containers with format
specification buffers. |
| **Output** | **Output** |
| Filesink | Stores the resulting stream in a
/opt/video.mp4 file. |
| Playback | Use the following command to pull video.mp4
from the host machine and play it on a media player
application:
`scp root@ device>:/opt/ directory>` |
## Variant 2: Use qtivcomposer to mix original frame with bounding box mask
Use the following command to execute the use
case:
gst-launch-1.0 -e \
qtiqmmfsrc name=camsrc ! video/x-raw\(memory:GBM\),format=NV12,width=1280,height=720,framerate=30/1,compression=ubwc ! queue ! tee name=split \
split. ! queue ! qtivcomposer name=mixer ! queue ! video/x-raw\(memory:GBM\),format=NV12,width=1920,height=1080,interlace-mode=progressive,colorimetry=bt601 ! v4l2h264enc capture-io-mode=5 output-io-mode=5 ! h264parse ! queue ! mp4mux ! queue ! filesink location=/opt/video.mp4 \
split. ! queue ! qtimlvconverter ! queue ! qtimltflite delegate=external external-delegate-path=libQnnTFLiteDelegate.so external-delegate-options="QNNExternalDelegate,backend_type=htp;" model=/opt/yolov5.tflite ! queue ! qtimlvdetection threshold=75.0 results=10 module=yolov5 labels=/opt/yolov5.labels constants="YoloV5,q-offsets=<3.0>,q-scales=<0.005047998391091824>;" ! video/x-raw,format=BGRA,width=640,height=360 ! queue ! mixer.Copy to clipboard
To
stop the use case, press CTRL + C.
Figure : Pipeline for bounding box mask and encode with qtivcomposer

The figure shows the flow of the use case execution:
1. Identify object scenes from a video stream, which is coming through a camera
source.
2. Compose bounding boxes over objects detected and original video stream using
qtivcomposer.
3. Encode this stream as a H.264 bitstream.
4. Multiplex the stream in a MP4 container and stored as a MP4 file.
The table provides the sequential processing stages of the pipeline execution:
| Process | Description |
| --- | --- |
| [qtiqmmfsrc](https://docs.qualcomm.com/doc/80-70014-50/topic/qtiqmmfsrc.html) |
- Collects the video stream (source) and creates two copies of
the source:
- One stream is sent to qtimetamux plugin to retain
the video stream.
- The other stream is sent to a ML inferencing
pipeline.
|
| **Preprocessing** | **Preprocessing** |
| [qtimlvconverter](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimlvconverter.html) |
- Receives the video stream on its sink pad.
- Performs preprocessing:
- Color conversion
- Scaling down/up
- Normalization on the stream data when model expects
floating point values as input
- Converts the video stream to a tensor stream on its source
pad.The object detection model uses this tensor
stream for inferencing.
|
| **Inferencing** | **Inferencing** |
| [qtimltflite](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimltflite.html) |
- Loads the object detection model.
- Modifies the graph for the chosen delegate.
- Receives the tensor stream on its sinkpad.
- Executes the inference and produces tensor stream with the
object detection results on its source pad.
|
| **Postprocessing** | **Postprocessing** |
| [qtimlvdetection](https://docs.qualcomm.com/doc/80-70014-50/topic/qtimlvdetection.html) |
- Receives the inference tensors from the object detection
model.
- Converts the inference tensors on its sinkpad into formats
like video or text that the multimedia plugins can process
later.
- Applies the threshold to the chosen number of results.
- Loads the corresponding modules for detection models.
In
this use case, qtimlvdetection does the following:
- Loads the YOLOv5 submodule.
- Produces video frames with only bounding boxes that
can be overlaid on objects.
- Sends them to sinkpad of qtivcomposer.
|
| [qtivcomposer](https://docs.qualcomm.com/doc/80-70014-50/topic/qtivcomposer.html) |
- Receives the original video stream and video stream with
bounding boxes on its sinkpads
- On its sourcepads, produces content that is composed of
video streams processed from its sinkpads.
|
| [v4l2h264enc](https://docs.qualcomm.com/doc/80-70014-50/topic/v4l2h264enc.html) |
- Applies parameters to each frame of the video stream its
receiving on its sinkpad.
- Encodes it into bitstream and sends it over its
sourcepad.
|
| h264parse | Adds additional information corresponding to the bitstream to
GStreamer buffer meta. |
| mp4mux | Receives these buffers and creates containers with format
specification buffers. |
| **Output** | **Output** |
| Filesink | Stores the resulting stream in a
/opt/video.mp4 file. |
| Playback | Use the following command to pull video.mp4
from the host machine and play it on a media player
application:
`scp root@ device>:/opt/ directory>` |
**Parent Topic:** [TensorFlow Lite use cases](https://docs.qualcomm.com/doc/80-70014-50/topic/tensorflow-lite-use-cases.html)
Last Published: Oct 27, 2025
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