libcamera: Rename "shutter speed" to "exposure time"

The terms "shutter" and "shutter speed" are used through libcamera to
mean "exposure time". This is confusing, both due to "speed" being used
as "time" while it should be the inverse (i.e. a maximum speed should
correspond to the minimum time), and due to "shutter speed" and
"exposure time" being used in different places with the same meaning.

To improve clarity of the code base and the documentation, use "exposure
time" consistently to replace "shutter speed".

This rename highlighted another vocabulary issue in libcamera. The
ExposureModeHelper::splitExposure() function used to document that it
splits "exposure time into shutter time and gain". It has been reworded
to "split exposure into exposure time and gain". That is not entirely
satisfactory, as "exposure" has a defined meaning in photography (see
https://en.wikipedia.org/wiki/Exposure_(photography)) that is not
expressed as a duration. This issue if left to be addressed separately.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Acked-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

5 files changed, 8 insertions, 8 deletions

diff --git a/src/ipa/rpi/cam_helper/cam_helper.cpp b/src/ipa/rpi/cam_helper/cam_helper.cpp
index ee5d011f..6493e882 100644
--- a/src/ipa/rpi/cam_helper/cam_helper.cpp
+++ b/src/ipa/rpi/cam_helper/cam_helper.cpp
@@ -241,7 +241,7 @@ void CamHelper::parseEmbeddedData(Span<const uint8_t> buffer,
 		return;
 	}
 
-	deviceStatus.shutterSpeed = parsedDeviceStatus.shutterSpeed;
+	deviceStatus.exposureTime = parsedDeviceStatus.exposureTime;
 	deviceStatus.analogueGain = parsedDeviceStatus.analogueGain;
 	deviceStatus.frameLength = parsedDeviceStatus.frameLength;
 	deviceStatus.lineLength = parsedDeviceStatus.lineLength;
diff --git a/src/ipa/rpi/cam_helper/cam_helper_imx219.cpp b/src/ipa/rpi/cam_helper/cam_helper_imx219.cpp
index 91461f7a..ba01153e 100644
--- a/src/ipa/rpi/cam_helper/cam_helper_imx219.cpp
+++ b/src/ipa/rpi/cam_helper/cam_helper_imx219.cpp
@@ -99,7 +99,7 @@ void CamHelperImx219::populateMetadata(const MdParser::RegisterMap &registers,
 
 	deviceStatus.lineLength = lineLengthPckToDuration(registers.at(lineLengthHiReg) * 256 +
 							  registers.at(lineLengthLoReg));
-	deviceStatus.shutterSpeed = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
+	deviceStatus.exposureTime = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
 					     deviceStatus.lineLength);
 	deviceStatus.analogueGain = gain(registers.at(gainReg));
 	deviceStatus.frameLength = registers.at(frameLengthHiReg) * 256 + registers.at(frameLengthLoReg);
diff --git a/src/ipa/rpi/cam_helper/cam_helper_imx477.cpp b/src/ipa/rpi/cam_helper/cam_helper_imx477.cpp
index 6bd89334..a53c40cd 100644
--- a/src/ipa/rpi/cam_helper/cam_helper_imx477.cpp
+++ b/src/ipa/rpi/cam_helper/cam_helper_imx477.cpp
@@ -112,7 +112,7 @@ void CamHelperImx477::prepare(libcamera::Span<const uint8_t> buffer, Metadata &m
 		DeviceStatus parsedDeviceStatus;
 
 		metadata.get("device.status", parsedDeviceStatus);
-		parsedDeviceStatus.shutterSpeed = deviceStatus.shutterSpeed;
+		parsedDeviceStatus.exposureTime = deviceStatus.exposureTime;
 		parsedDeviceStatus.frameLength = deviceStatus.frameLength;
 		metadata.set("device.status", parsedDeviceStatus);
 
@@ -180,7 +180,7 @@ void CamHelperImx477::populateMetadata(const MdParser::RegisterMap &registers,
 
 	deviceStatus.lineLength = lineLengthPckToDuration(registers.at(lineLengthHiReg) * 256 +
 							  registers.at(lineLengthLoReg));
-	deviceStatus.shutterSpeed = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
+	deviceStatus.exposureTime = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
 					     deviceStatus.lineLength);
 	deviceStatus.analogueGain = gain(registers.at(gainHiReg) * 256 + registers.at(gainLoReg));
 	deviceStatus.frameLength = registers.at(frameLengthHiReg) * 256 + registers.at(frameLengthLoReg);
diff --git a/src/ipa/rpi/cam_helper/cam_helper_imx519.cpp b/src/ipa/rpi/cam_helper/cam_helper_imx519.cpp
index c2de3d40..2ff08653 100644
--- a/src/ipa/rpi/cam_helper/cam_helper_imx519.cpp
+++ b/src/ipa/rpi/cam_helper/cam_helper_imx519.cpp
@@ -112,7 +112,7 @@ void CamHelperImx519::prepare(libcamera::Span<const uint8_t> buffer, Metadata &m
 		DeviceStatus parsedDeviceStatus;
 
 		metadata.get("device.status", parsedDeviceStatus);
-		parsedDeviceStatus.shutterSpeed = deviceStatus.shutterSpeed;
+		parsedDeviceStatus.exposureTime = deviceStatus.exposureTime;
 		parsedDeviceStatus.frameLength = deviceStatus.frameLength;
 		metadata.set("device.status", parsedDeviceStatus);
 
@@ -180,7 +180,7 @@ void CamHelperImx519::populateMetadata(const MdParser::RegisterMap &registers,
 
 	deviceStatus.lineLength = lineLengthPckToDuration(registers.at(lineLengthHiReg) * 256 +
 							  registers.at(lineLengthLoReg));
-	deviceStatus.shutterSpeed = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
+	deviceStatus.exposureTime = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
 					     deviceStatus.lineLength);
 	deviceStatus.analogueGain = gain(registers.at(gainHiReg) * 256 + registers.at(gainLoReg));
 	deviceStatus.frameLength = registers.at(frameLengthHiReg) * 256 + registers.at(frameLengthLoReg);
diff --git a/src/ipa/rpi/cam_helper/cam_helper_imx708.cpp b/src/ipa/rpi/cam_helper/cam_helper_imx708.cpp
index 63ddb55e..ec83d9fd 100644
--- a/src/ipa/rpi/cam_helper/cam_helper_imx708.cpp
+++ b/src/ipa/rpi/cam_helper/cam_helper_imx708.cpp
@@ -155,7 +155,7 @@ void CamHelperImx708::prepare(libcamera::Span<const uint8_t> buffer, Metadata &m
 		DeviceStatus parsedDeviceStatus;
 
 		metadata.get("device.status", parsedDeviceStatus);
-		parsedDeviceStatus.shutterSpeed = deviceStatus.shutterSpeed;
+		parsedDeviceStatus.exposureTime = deviceStatus.exposureTime;
 		parsedDeviceStatus.frameLength = deviceStatus.frameLength;
 		metadata.set("device.status", parsedDeviceStatus);
 
@@ -255,7 +255,7 @@ void CamHelperImx708::populateMetadata(const MdParser::RegisterMap &registers,
 
 	deviceStatus.lineLength = lineLengthPckToDuration(registers.at(lineLengthHiReg) * 256 +
 							  registers.at(lineLengthLoReg));
-	deviceStatus.shutterSpeed = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
+	deviceStatus.exposureTime = exposure(registers.at(expHiReg) * 256 + registers.at(expLoReg),
 					     deviceStatus.lineLength);
 	deviceStatus.analogueGain = gain(registers.at(gainHiReg) * 256 + registers.at(gainLoReg));
 	deviceStatus.frameLength = registers.at(frameLengthHiReg) * 256 + registers.at(frameLengthLoReg);