Switch linear vs. SHDR mode automatically - Qualcomm Dragonwing Documentation

QCS6490Stable

vhdr=3

Activation Flag

Linear ↔ SHDR

Seamless Switch

Pre-initialized

Low Latency

Platform Scope:
This feature is applicable for QCS6490 only.

01 · What Is It?

This feature enables on-the-fly switching between Linear and SHDR v2 mode pipelines without terminating the active camera session. Key architectural benefits include:

Session Continuity: Prevents video session interruption during light-level (lux) fluctuations.
Latency Optimization: Pipelines are pre-initialized during session creation to minimize switch overhead.
Resource Management: Automatically releases and re-acquires hardware blocks (Sensor, IFE, IPE) during the reconfiguration phase.

This feature works only for SHDR v2 and Linear mode pipelines.

02 · Verification Setup

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

Initialize Log Collection

Run the following command on the device to monitor runtime events:

Log Collection

# journalctl -f > /opt/log.txt

03 · Feature Validation

Use vhdr=3 in a GST command to enable this feature. To enable the feature and toggle between Linear and SHDR modes:

Execute Metadata Application

Run the gst-camera-metadata-example application to support runtime vendor tag configuration.

GStreamer (Auto Mode Switch)

gst-camera-metadata-example -p "qtiqmmfsrc name=camsrc camera=0 vhdr=3 ! \
video/x-raw,format=NV12,width=3840,height=2160,framerate=30/1,\
interlace-mode=progressive,colorimetry=bt601 ! queue ! v4l2h264enc capture-io-mode=4 \
output-io-mode=5 ! queue ! h264parse ! mp4mux ! queue ! filesink location=/opt/mux4k.mp4"

Transition to READY

In the application, select (1) READY.

Initialize PLAYING State

Select (3) PLAYING. The camera starts in linear mode.

Open Metadata Menu

Select (4) META. The following menu is shown:

Metadata Root Menu

 ---------MENU---------
(1)        video-metadata
(2)        image-metadata
(3)        static-metadata
(4)        session-metadata

Select Video Category

Select (1) video-metadata. The following menu is shown:

Video Metadata Menu

 ---------video-metadata---------
(1)        List all available tags
(2)        Dump all tags values in a file
(3)        Dump custom tags values in a file
(4)        Get a tag
(5)        Set a tag

Invoke Tag Modification

Select (5) Set a tag.

Define Vendor Tag

A prompt appears to enter the section name and tag name separated by spaces without quotes. Enter: org.quic.camera.videoHDRmode modeType

Trigger Mode Switch

A prompt appears to set the value. Enter 1 to switch to SHDR mode.

To toggle between Linear and SHDR modes, repeat this process and enter 1 (SHDR mode) and 0 (Linear mode) as needed.

To close the camera, select (q) QUIT or press CTRL + C.

04 · Log Verification

Verify the pipeline reconfiguration by checking the following log signatures:

Linear Mode Selection

CamX Status (Linear)

cam-server[1693]: CamX: [REQMAP]1693 2652 [CORE   ] camxsession.cpp:4811
ProcessRequest() chiFrameNum: 0 <==> requestId: 1 <==> sequenceId: 0
<==> CSLSyncId: 1 -- RealTimeFeatureZSLPreviewRawYUV_0

SHDR Mode Selection

CamX Status (SHDR)

cam-server[1693]: CamX: [REQMAP]1693 2652 [CORE   ] camxsession.cpp:4811
ProcessRequest() chiFrameNum: 296 <==> requestId: 297 <==> sequenceId:
296 <==> CSLSyncId: 297 -- RealTimeSHDR_0

vhdr=3

Linear ↔ SHDR

Pre-initialized

​01 · What Is It?

​02 · Verification Setup

​03 · Feature Validation

​04 · Log Verification

​Linear Mode Selection

​SHDR Mode Selection

01 · What Is It?

02 · Verification Setup

03 · Feature Validation

04 · Log Verification

Linear Mode Selection

SHDR Mode Selection