spolifroni-amd
07d8e3e69a
* Updated the readme file to point to the official documentation
* first commit of new documentation structure
* split up and reconfigured Using rocJpeg
* Updated the readme file to point to the official documentation
* first commit of new documentation structure
* split up and reconfigured Using rocJpeg
* fixed missing space
* All changes asked for in the PR except the Destroy Handles part.
* separated creating and destroying handles; added a destroying handles section; added links to hipmalloc() and hipfree()
* removed the installation and build sections so that it doesn't conflict/go out of sync with the official doc
* putting readme back the way it was, minus documentation section
* changed some wording around hipFree()
[ROCm/rocjpeg commit: 31610c7472]
64 строки
2.2 KiB
ReStructuredText
64 строки
2.2 KiB
ReStructuredText
.. meta::
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:description: retrieving image information with rocJPEG
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:keywords: rocJPEG, ROCm, API, documentation, image information, jpeg
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********************************************************************
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Retrieving image information with rocJPEG
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********************************************************************
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Retrieving image information is done using ``rocJpegGetImageInfo()``.
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.. code:: cpp
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RocJpegStatus rocJpegGetImageInfo(
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RocJpegHandle handle,
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RocJpegStreamHandle jpeg_stream_handle,
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uint8_t *num_components,
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RocJpegChromaSubsampling *subsampling,
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uint32_t *widths,
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uint32_t *heights);
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``rocJpegGetImageInfo()`` takes the ``RocJpegHandle`` and a ``RocJpegStreamHandle`` as inputs, and returns the subsampling, number of components, and widths and heights of the components. These are passed to the ``subsampling``, ``num_components``, and ``widths`` and ``heights`` output parameters.
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The ``subsampling`` output parameter is a ``RocJpegChromaSubsampling`` enum.
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.. code:: cpp
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typedef enum {
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ROCJPEG_CSS_444 = 0,
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ROCJPEG_CSS_440 = 1,
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ROCJPEG_CSS_422 = 2,
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ROCJPEG_CSS_420 = 3,
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ROCJPEG_CSS_411 = 4,
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ROCJPEG_CSS_400 = 5,
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ROCJPEG_CSS_UNKNOWN = -1
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} RocJpegChromaSubsampling;
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Its value is set to the chroma subsampling retrieved from the image.
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For example:
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.. code:: cpp
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// Get the image info
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uint8_t num_components;
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RocJpegChromaSubsampling subsampling;
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uint32_t widths[ROCJPEG_MAX_COMPONENT] = {};
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uint32_t heights[ROCJPEG_MAX_COMPONENT] = {};
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status = rocJpegGetImageInfo(handle, rocjpeg_stream_handle, &num_components, &subsampling, widths, heights);
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if (status != ROCJPEG_STATUS_SUCCESS) {
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std::cerr << "Failed to get image info with error code: " << rocJpegGetErrorName(status) << std::endl;
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rocJpegStreamDestroy(rocjpeg_stream_handle);
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rocJpegDestroy(handle);
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return EXIT_FAILURE;
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}
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``rocJpegGetImageInfo()`` is thread safe.
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.. note::
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The VCN hardware-accelerated JPEG decoder in AMD GPUs only supports decoding JPEG images with ``ROCJPEG_CSS_444``, ``ROCJPEG_CSS_440``, ``ROCJPEG_CSS_422``, ``ROCJPEG_CSS_420``, and ``ROCJPEG_CSS_400`` chroma subsampling.
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