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Diffstat (limited to 'en/devices/camera/camera3_crop_reprocess.html')
| -rw-r--r-- | en/devices/camera/camera3_crop_reprocess.html | 98 |
1 files changed, 49 insertions, 49 deletions
diff --git a/en/devices/camera/camera3_crop_reprocess.html b/en/devices/camera/camera3_crop_reprocess.html index 00c5bbed..1e24db3b 100644 --- a/en/devices/camera/camera3_crop_reprocess.html +++ b/en/devices/camera/camera3_crop_reprocess.html @@ -24,21 +24,21 @@ <h2 id="output-stream">Output streams</h2> -<p> Unlike the old camera subsystem, which has 3-4 different ways of producing data - from the camera (ANativeWindow-based preview operations, preview callbacks, - video callbacks, and takePicture callbacks), the new subsystem operates solely - on the ANativeWindow-based pipeline for all resolutions and output formats. - Multiple such streams can be configured at once, to send a single frame to many - targets such as the GPU, the video encoder, RenderScript, or app-visible buffers +<p> Unlike the old camera subsystem, which has 3-4 different ways of producing data + from the camera (ANativeWindow-based preview operations, preview callbacks, + video callbacks, and takePicture callbacks), the new subsystem operates solely + on the ANativeWindow-based pipeline for all resolutions and output formats. + Multiple such streams can be configured at once, to send a single frame to many + targets such as the GPU, the video encoder, RenderScript, or app-visible buffers (RAW Bayer, processed YUV buffers, or JPEG-encoded buffers).</p> -<p>As an optimization, these output streams must be configured ahead of time, and - only a limited number may exist at once. This allows for pre-allocation of - memory buffers and configuration of the camera hardware, so that when requests - are submitted with multiple or varying output pipelines listed, there won't be +<p>As an optimization, these output streams must be configured ahead of time, and + only a limited number may exist at once. This allows for pre-allocation of + memory buffers and configuration of the camera hardware, so that when requests + are submitted with multiple or varying output pipelines listed, there won't be delays or latency in fulfilling the request.</p> -<p>To support backwards compatibility with the current camera API, at least 3 - simultaneous YUV output streams must be supported, plus one JPEG stream. This is - required for video snapshot support with the application also receiving YUV +<p>To support backwards compatibility with the current camera API, at least 3 + simultaneous YUV output streams must be supported, plus one JPEG stream. This is + required for video snapshot support with the application also receiving YUV buffers:</p> <ul> <li>One stream to the GPU/SurfaceView (opaque YUV format) for preview</li> @@ -49,48 +49,48 @@ <p>The exact requirements are still being defined since the corresponding API isn't yet finalized.</p> <h2>Cropping</h2> -<p>Cropping of the full pixel array (for digital zoom and other use cases where a - smaller FOV is desirable) is communicated through the ANDROID_SCALER_CROP_REGION - setting. This is a per-request setting, and can change on a per-request basis, +<p>Cropping of the full pixel array (for digital zoom and other use cases where a + smaller FOV is desirable) is communicated through the ANDROID_SCALER_CROP_REGION + setting. This is a per-request setting, and can change on a per-request basis, which is critical for implementing smooth digital zoom.</p> -<p>The region is defined as a rectangle (x, y, width, height), with (x, y) - describing the top-left corner of the rectangle. The rectangle is defined on the - coordinate system of the sensor active pixel array, with (0,0) being the - top-left pixel of the active pixel array. Therefore, the width and height cannot - be larger than the dimensions reported in the ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY - static info field. The minimum allowed width and height are reported by the HAL - through the ANDROID_SCALER_MAX_DIGITAL_ZOOM static info field, which describes - the maximum supported zoom factor. Therefore, the minimum crop region width and +<p>The region is defined as a rectangle (x, y, width, height), with (x, y) + describing the top-left corner of the rectangle. The rectangle is defined on the + coordinate system of the sensor active pixel array, with (0,0) being the + top-left pixel of the active pixel array. Therefore, the width and height cannot + be larger than the dimensions reported in the ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY + static info field. The minimum allowed width and height are reported by the HAL + through the ANDROID_SCALER_MAX_DIGITAL_ZOOM static info field, which describes + the maximum supported zoom factor. Therefore, the minimum crop region width and height are:</p> -<pre> +<pre class="devsite-click-to-copy"> {width, height} = { floor(ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY[0] / ANDROID_SCALER_MAX_DIGITAL_ZOOM), floor(ANDROID_SENSOR_ACTIVE_PIXEL_ARRAY[1] / ANDROID_SCALER_MAX_DIGITAL_ZOOM) } - </pre> -<p>If the crop region needs to fulfill specific requirements (for example, it needs - to start on even coordinates, and its width/height needs to be even), the HAL - must do the necessary rounding and write out the final crop region used in the - output result metadata. Similarly, if the HAL implements video stabilization, it - must adjust the result crop region to describe the region actually included in - the output after video stabilization is applied. In general, a camera-using - application must be able to determine the field of view it is receiving based on +</pre> +<p>If the crop region needs to fulfill specific requirements (for example, it needs + to start on even coordinates, and its width/height needs to be even), the HAL + must do the necessary rounding and write out the final crop region used in the + output result metadata. Similarly, if the HAL implements video stabilization, it + must adjust the result crop region to describe the region actually included in + the output after video stabilization is applied. In general, a camera-using + application must be able to determine the field of view it is receiving based on the crop region, the dimensions of the image sensor, and the lens focal length.</p> -<p>Since the crop region applies to all streams, which may have different aspect - ratios than the crop region, the exact sensor region used for each stream may be - smaller than the crop region. Specifically, each stream should maintain square - pixels and its aspect ratio by minimally further cropping the defined crop - region. If the stream's aspect ratio is wider than the crop region, the stream - should be further cropped vertically, and if the stream's aspect ratio is - narrower than the crop region, the stream should be further cropped +<p>Since the crop region applies to all streams, which may have different aspect + ratios than the crop region, the exact sensor region used for each stream may be + smaller than the crop region. Specifically, each stream should maintain square + pixels and its aspect ratio by minimally further cropping the defined crop + region. If the stream's aspect ratio is wider than the crop region, the stream + should be further cropped vertically, and if the stream's aspect ratio is + narrower than the crop region, the stream should be further cropped horizontally.</p> -<p>In all cases, the stream crop must be centered within the full crop region, and - each stream is only either cropped horizontally or vertical relative to the full +<p>In all cases, the stream crop must be centered within the full crop region, and + each stream is only either cropped horizontally or vertical relative to the full crop region, never both.</p> -<p>For example, if two streams are defined, a 640x480 stream (4:3 aspect), and a - 1280x720 stream (16:9 aspect), below demonstrates the expected output regions - for each stream for a few sample crop regions, on a hypothetical 3 MP (2000 x +<p>For example, if two streams are defined, a 640x480 stream (4:3 aspect), and a + 1280x720 stream (16:9 aspect), below demonstrates the expected output regions + for each stream for a few sample crop regions, on a hypothetical 3 MP (2000 x 1500 pixel array) sensor.</p> </p> Crop region: (500, 375, 1000, 750) (4:3 aspect ratio)<br/> @@ -118,7 +118,7 @@ isn't yet finalized.</p> <strong>Figure 3.</strong> 1:1 aspect ratio </p> <p> - And a final example, a 1024x1024 square aspect ratio stream instead of the 480p + And a final example, a 1024x1024 square aspect ratio stream instead of the 480p stream:<br/> Crop region: (500, 375, 1000, 750) (4:3 aspect ratio)<br/> 1024x1024 stream crop: (625, 375, 750, 750)<br/> @@ -129,9 +129,9 @@ isn't yet finalized.</p> <strong>Figure 4.</strong> 4:3 aspect ratio, square </p> <h2 id="reprocessing">Reprocessing</h2> -<p> Additional support for raw image files is provided by reprocessing support for RAW Bayer - data. This support allows the camera pipeline to process a previously captured - RAW buffer and metadata (an entire frame that was recorded previously), to +<p> Additional support for raw image files is provided by reprocessing support for RAW Bayer + data. This support allows the camera pipeline to process a previously captured + RAW buffer and metadata (an entire frame that was recorded previously), to produce a new rendered YUV or JPEG output.</p> </body> |