Multi-Camera Offline IFE - Qualcomm Dragonwing Documentation

IQ-9075-EVKIQ-8275-EVKStable

4

Cameras (IQ-9075-EVK)

3

Cameras (IQ-8275-EVK)

1

IFE Hardware Used

SFE

Bus Fetch Engine

Platform Scope:
This feature is applicable for IQ-9075-EVK and IQ-8275-EVK only.
Both platforms have two IFEs that natively support real-time de-bayering of bayer camera images.

01 · What Is It?

The Offline IFE feature allows a single IFE hardware instance to process bayer images from multiple cameras by running in offline mode. Instead of real-time de-bayering, frames are first stored in DDR via IFE-Lite’s RDI port, then fetched by the IFE using the SFE Lite bus engine for bayer-to-YUV conversion.

Real-Time Path:    Sensor → IFE-Lite (RDI) → DDR
Offline Path:      DDR → SFE Lite (Fetch) → IFE Offline → YUV Output

02 · What Does It Control?

Controls how many concurrent bayer cameras can stream simultaneously by reusing a single IFE in offline mode rather than requiring dedicated IFE instances per camera.

Capability	Without Offline IFE	With Offline IFE
Concurrent bayer cameras	2 cameras max	4 cameras (IQ-9075-EVK)
IFE instances required	1 per 2 cameras	1 shared (offline)
Frame routing	Direct sensor → IFE	Sensor → IFE-Lite → DDR → IFE
SFE Lite usage	Not used	Used as bus fetch engine
IQ-8275-EVK camera count	2 cameras max	3 cameras

03 · Feature Validation

Connect to the device console using SSH. See How To SSH? for instructions.

Platform Reference Configurations

Ensure you have connected one of the following camera configurations:

IQ-9075-EVK: Four OV9282 MIPI cameras connected to four MIPI CSI slots (0, 1, 2, and 3).
IQ-8275-EVK: Three OV9282 MIPI cameras connected to three MIPI CSI slots (0, 1, and 2).

IQ-9075-EVK Config

Key	Value
Camera count	4
Sensor	OV9282 MIPI
MIPI CSI slots	0, 1, 2, 3
Format	NV12 1280×720

IQ-8275-EVK Config

Key	Value
Camera count	3
Sensor	OV9282 MIPI
MIPI CSI slots	0, 1, 2
Format	NV12 1280×720

Collect user log

Collect User Log

# On device console
journalctl -f > /opt/user_log.txt

Collect kernel log

Collect Kernel Log

dmesg -w  > /opt/kernel_log.txt

Run GStreamer pipeline with multicamera-hint=true

Run the following for each camera (change camera=0 to 1, 2, 3 accordingly):

GStreamer Pipeline

gst-launch-1.0 -e qtiqmmfsrc name=camsrc camera=0 multicamera-hint=true ! \
video/x-raw,format=NV12,width=1280,height=720,framerate=30/1,\
interlace-mode=progressive,colorimetry=bt601 ! v4l2h264enc \
capture-io-mode=4 output-io-mode=5 extra-controls="controls,video_bitrate=6000000,\
video_bitrate_mode=0;" ! h264parse ! mp4mux ! filesink location=/opt/mux_avc.mp4

Repeat for each camera
Run similarly for camera=1, camera=2, and camera=3 (IQ-9075-EVK) or up to camera=2 (IQ-8275-EVK) with multicamera-hint=true on each.

Verify log output

After running the pipeline, confirm the feature is active by checking these exact log entries:User log — CamX pipeline status:

User Log Trace

CamX: [CORE_CFG]3509 3556 [CORE   ] camxpipeline.h:4222 SetPipelineStatus() RealTimeFeatureZSLPreviewRawOfflineIFE_0_cam_0 status is now PipelineStatus::STREAM_ON

Kernel log — IFE acquisition confirmation:

Kernel Log Trace

CAM_INFO: CAM-ISP: cam_ife_hw_mgr_print_acquire_info: 1733: 0:4:11.835 Acquired Single IFE[0] SFE[0] OFFLINE: Y with [9 pix] [0 pd] [0 rdi] ports for ctx:1

OFFLINE: Y in the kernel log confirms the IFE is running in offline mode. STREAM_ON in the user log confirms the CamX pipeline is live.

🛠️ Troubleshooting

Issue	Cause	Fix
Only 2 cameras stream; 3rd/4th dropped	`multicamera-hint=true` not set on all streams	Ensure every `gst-launch` call includes `multicamera-hint=true`
`OFFLINE: N` in kernel log	Offline IFE not acquired — possible resource conflict	Restart camera service; verify no other pipeline is holding IFE
Pipeline stalls or drops frames	DDR bandwidth saturation at 4-camera load	Reduce framerate to 24fps or lower resolution to 720p

4

3

1

SFE

​01 · What Is It?

​02 · What Does It Control?

​03 · Feature Validation

​Platform Reference Configurations

IQ-9075-EVK Config

IQ-8275-EVK Config

​🛠️ Troubleshooting

01 · What Is It?

02 · What Does It Control?

03 · Feature Validation

Platform Reference Configurations

🛠️ Troubleshooting