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fix(jpeg): JPEG can encode and decode in encryption situation
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C.S.M
@@ -17,15 +17,18 @@ Functional Overview
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This document covers the following sections:
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- `Resource Allocation <#resource-allocation>`__ - covers how to allocate JPEG resources with properly set of configurations. It also covers how to recycle the resources when they finished working.
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- `Finite State Machine <#finite-state-machine>`__ - covers JPEG workflow. Introduce how jpeg driver uses internal resources and its software process.
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- `JPEG Decoder Engine <#jpeg-decoder-engine>`__ - covers behavior of JPEG decoder engine. Introduce how to use decoder engine functions to decode an image (from jpg format to raw format).
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- `JPEG Encoder Engine <#jpeg-encoder-engine>`__ - covers behavior of JPEG encoder engine. Introduce how to use encoder engine functions to encode an image (from raw format to jpg format).
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- `Performance Overview <#performance-overview>`__ - covers encoder and decoder performance.
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- `Pixel Storage Layout for Different Color Formats <#pixel-storage-layout-for-different-color-formats>`__ - covers color space order overview required in this JPEG decoder and encoder.
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- `Thread Safety <#thread-safety>`__ - lists which APIs are guaranteed to be thread safe by the driver.
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- `Power Management <#power-management>`__ - describes how JPEG driver would be affected by power consumption.
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- `Kconfig Options <#kconfig-options>`__ - lists the supported Kconfig options that can bring different effects to the driver.
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- :ref:`jpeg-resource-allocation` - covers how to allocate JPEG resources with properly set of configurations. It also covers how to recycle the resources when they finished working.
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- :ref:`jpeg-finite-state-machine` - covers JPEG workflow. Introduce how jpeg driver uses internal resources and its software process.
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- :ref:`jpeg-decoder-engine` - covers behavior of JPEG decoder engine. Introduce how to use decoder engine functions to decode an image (from jpg format to raw format).
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- :ref:`jpeg-encoder-engine` - covers behavior of JPEG encoder engine. Introduce how to use encoder engine functions to encode an image (from raw format to jpg format).
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- :ref:`jpeg-performance-overview` - covers encoder and decoder performance.
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- :ref:`jpeg-pixel-storage-layout` - covers color space order overview required in this JPEG decoder and encoder.
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- :ref:`jpeg-thread-safety` - lists which APIs are guaranteed to be thread safe by the driver.
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- :ref:`jpeg-power-management` - describes how JPEG driver would be affected by power consumption.
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- :ref:`jpeg-flash-encryption` - describes how to use the JPEG codec correctly when flash/PSRAM encryption is enabled.
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- :ref:`jpeg-kconfig-options` - lists the supported Kconfig options that can bring different effects to the driver.
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.. _jpeg-resource-allocation:
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Resource Allocation
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^^^^^^^^^^^^^^^^^^^
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@@ -85,6 +88,8 @@ If a previously installed JPEG engine is no longer needed, it's recommended to r
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ESP_ERROR_CHECK(jpeg_del_encoder_engine(encoder_engine));
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.. _jpeg-finite-state-machine:
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Finite State Machine
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^^^^^^^^^^^^^^^^^^^^
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@@ -96,6 +101,8 @@ The JPEG driver usage of hardware resources and its process workflow are shown i
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JPEG finite state machine
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.. _jpeg-decoder-engine:
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JPEG Decoder Engine
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^^^^^^^^^^^^^^^^^^^
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@@ -153,6 +160,8 @@ There are some tips that can help you use this driver more accurately:
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3. If the source JPEG uses YUV420 or YUV422 sampling, the decoded output dimensions can be padded up to 16-pixel boundaries. For example, if the visible image size is 1080*1920, the decoder may require an output buffer sized for 1088*1920 pixels. This comes from the JPEG block layout, so please provide enough output buffer memory for the padded image, not only for the visible width and height.
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.. _jpeg-encoder-engine:
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JPEG Encoder Engine
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^^^^^^^^^^^^^^^^^^^
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@@ -212,6 +221,8 @@ There are some tips that can help you use this driver more accurately:
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4. The compression ratio depends on the chosen `image_quality` and the content of the image itself. Generally, a higher `image_quality` value obviously results in better image quality but a smaller compression ratio. As for the image content, it is hard to give any specific guidelines, so this question is out of the scope of this document. Generally, the baseline JPEG compression ratio can vary from 40:1 to 10:1. Please take the actual situation into account.
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.. _jpeg-performance-overview:
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Performance Overview
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^^^^^^^^^^^^^^^^^^^^
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@@ -343,6 +354,8 @@ JPEG encoder performance
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.. [#] Format of Original Image
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.. [#] Down sampling method
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.. _jpeg-pixel-storage-layout:
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Pixel Storage Layout for Different Color Formats
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@@ -419,11 +432,15 @@ In the following picture, each small block means one byte.
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YUV420 pixel order
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.. _jpeg-thread-safety:
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Thread Safety
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^^^^^^^^^^^^^
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The factory function :cpp:func:`jpeg_new_decoder_engine`, :cpp:func:`jpeg_decoder_get_info`, :cpp:func:`jpeg_decoder_process`, and :cpp:func:`jpeg_del_decoder_engine` are guaranteed to be thread safe by the driver, which means, user can call them from different RTOS tasks without protection by extra locks.
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.. _jpeg-power-management:
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Power Management
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^^^^^^^^^^^^^^^^
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@@ -431,6 +448,26 @@ When power management is enabled (i.e., :ref:`CONFIG_PM_ENABLE` is set), the sys
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Whenever the user is decoding or encoding via JPEG (i.e., calling :cpp:func:`jpeg_encoder_process` or :cpp:func:`jpeg_decoder_process`), the driver guarantees that the power management lock is acquired by setting it to :cpp:enumerator:`esp_pm_lock_type_t::ESP_PM_CPU_FREQ_MAX`. Once the encoding or decoding is finished, the driver releases the lock and the system can enter Light-sleep.
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.. _jpeg-flash-encryption:
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Usage Under Encryption
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^^^^^^^^^^^^^^^^^^^^^^
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The JPEG codec moves data via the 2D-DMA, and the JPEG codec **cannot process encrypted data**. Therefore, when PSRAM encryption is enabled, the JPEG input/output buffers must reside in an unencrypted memory region, otherwise encoding/decoding fails.
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To support the encrypted scenario, the driver does the following:
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- When ``CONFIG_SPIRAM_ENC_EXEMPT`` is enabled, :cpp:func:`jpeg_alloc_decoder_mem` and :cpp:func:`jpeg_alloc_encoder_mem` allocate buffers from the unencrypted PSRAM region (``MALLOC_CAP_SPIRAM_NO_ENC``) automatically.
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- The allocated buffers satisfy both the cache line alignment and the byte alignment required by the 2D-DMA.
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Please note the following when using it:
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1. It is recommended to always allocate buffers via :cpp:func:`jpeg_alloc_encoder_mem` / :cpp:func:`jpeg_alloc_decoder_mem` to ensure correct alignment and memory region.
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2. The size of the unencrypted region is determined by ``CONFIG_SPIRAM_ENC_EXEMPT_SIZE``. Since the JPEG buffer size depends on the image resolution and cannot be predicted automatically, configure it according to the largest image you actually process. If the region is insufficient, the allocation fails and an error log is printed, suggesting to enlarge ``CONFIG_SPIRAM_ENC_EXEMPT_SIZE``. Also note that this value must not be greater than or equal to the actual PSRAM size, otherwise the unencrypted region is disabled.
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.. _jpeg-kconfig-options:
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Kconfig Options
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^^^^^^^^^^^^^^^
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@@ -17,15 +17,18 @@ JPEG 常用于数字图像，尤其是数码摄影图像的有损压缩。压缩
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本文档包含以下几部分内容：
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- `资源分配 <#resource-allocation>`__，包括如何正确地设置配置来分配 JPEG 资源、如何在完成工作时回收资源。
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- `有限状态机 <#finite-state-machine>`__，涵盖了 JPEG 的工作流程，介绍了 JPEG 驱动程序的软件流程，以及是如何使用内部资源的。
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- `JPEG 解码器引擎 <#jpeg_decoder_engine>`__，包括 JPEG 解码器引擎的行为。介绍了如何使用解码器引擎函数为图像解码（从 jpg 格式到 raw 格式）。
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- `JPEG 编码器引擎 <#jpeg_encoder_engine>`__，包括 JPEG 编码器引擎的行为。介绍了如何使用编码器引擎函数为图像编码（从 raw 格式到 jpg 格式）。
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- `性能概览 <#performance-overview>`__，介绍了编码器和解码器的性能。
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- `不同颜色格式的像素存储布局 <#pixel-storage-layout-for-different-color-formats>`__，涵盖了 JPEG 解码器和编码器所需的颜色空间顺序。
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- `线程安全性 <#thread-safety>`__， 列出了驱动程序能保证线程安全的 API。
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- `电源管理 <#power-management>`__，描述了影响 JPEG 驱动程序功耗的因素。
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- `Kconfig 选项 <#kconfig-options>`__，列出了支持的 Kconfig 选项，可以为驱动程序带来不同的效果。
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- :ref:`jpeg-resource-allocation`，包括如何正确地设置配置来分配 JPEG 资源、如何在完成工作时回收资源。
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- :ref:`jpeg-finite-state-machine`，涵盖了 JPEG 的工作流程，介绍了 JPEG 驱动程序的软件流程，以及是如何使用内部资源的。
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- :ref:`jpeg-decoder-engine`，包括 JPEG 解码器引擎的行为。介绍了如何使用解码器引擎函数为图像解码（从 jpg 格式到 raw 格式）。
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- :ref:`jpeg-encoder-engine`，包括 JPEG 编码器引擎的行为。介绍了如何使用编码器引擎函数为图像编码（从 raw 格式到 jpg 格式）。
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- :ref:`jpeg-performance-overview`，介绍了编码器和解码器的性能。
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- :ref:`jpeg-pixel-storage-layout`，涵盖了 JPEG 解码器和编码器所需的颜色空间顺序。
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- :ref:`jpeg-thread-safety`，列出了驱动程序能保证线程安全的 API。
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- :ref:`jpeg-power-management`，描述了影响 JPEG 驱动程序功耗的因素。
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- :ref:`jpeg-flash-encryption`，介绍了在 flash/PSRAM 加密场景下如何正确使用 JPEG 编解码器。
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- :ref:`jpeg-kconfig-options`，列出了支持的 Kconfig 选项，可以为驱动程序带来不同的效果。
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.. _jpeg-resource-allocation:
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资源分配
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^^^^^^^^
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@@ -85,6 +88,8 @@ JPEG 编码器引擎的配置需要由 :cpp:type:`jpeg_encode_engine_cfg_t` 指
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ESP_ERROR_CHECK(jpeg_del_encoder_engine(encoder_engine));
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.. _jpeg-finite-state-machine:
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有限状态机
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^^^^^^^^^^
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@@ -96,6 +101,8 @@ JPEG 驱动程序对硬件资源的使用情况及其处理流程如下图所示
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JPEG 有限状态机
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.. _jpeg-decoder-engine:
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JPEG 解码器引擎
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^^^^^^^^^^^^^^^
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@@ -153,6 +160,8 @@ JPEG 解码器引擎
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3. 如果源 JPEG 使用 YUV420 或 YUV422 采样方式，解码后的输出图像尺寸可能会被补齐到 16 像素边界。例如，当可见图像大小为 1080*1920 时，解码器可能需要按 1088*1920 像素来分配输出缓冲区。这来自 JPEG 的块布局限制，因此请按补齐后的图像尺寸而不是仅按可见宽高准备足够的输出缓冲区内存。
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.. _jpeg-encoder-engine:
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JPEG 编码器引擎
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^^^^^^^^^^^^^^^
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@@ -212,6 +221,8 @@ JPEG 编码器引擎
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4. 压缩比取决于所选择的 `image_quality` 和图像本身的内容。一般来说， `image_quality` 值越高，图像质量越好，相应的压缩比就越小。至于图像内容，则很难给出具体的指导方针，因此本文也就不再讨论。基准 JPEG 压缩比通常从 40:1 到 10:1 不等，请依实际情况而定。
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.. _jpeg-performance-overview:
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性能概述
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^^^^^^^^
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@@ -343,6 +354,8 @@ JPEG 编码器性能
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.. [#] 原图格式
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.. [#] 下采样法
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.. _jpeg-pixel-storage-layout:
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不同颜色格式的像素存储布局
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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@@ -419,11 +432,15 @@ YUV420
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YUV420 像素顺序
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.. _jpeg-thread-safety:
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线程安全性
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^^^^^^^^^^
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驱动程序能保证工厂函数 :cpp:func:`jpeg_new_decoder_engine`， :cpp:func:`jpeg_decoder_get_info`， :cpp:func:`jpeg_decoder_process`，以及 :cpp:func:`jpeg_del_decoder_engine` 是线程安全的，这意味着无需额外的锁保护，也可以从不同的 RTOS 任务中调用这些函数。
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.. _jpeg-power-management:
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电源管理
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^^^^^^^^
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@@ -431,6 +448,26 @@ YUV420
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每当用户通过 JPEG 进行解码或编码（即调用 :cpp:func:`jpeg_encoder_process` 或 :cpp:func:`jpeg_decoder_process`）时，驱动程序会将电源管理设定为 :cpp:enumerator:`esp_pm_lock_type_t::ESP_PM_CPU_FREQ_MAX`，确保获取电源管理锁。一旦编码或解码完成，驱动程序将释放锁，则系统可以进入 Light-sleep 模式。
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.. _jpeg-flash-encryption:
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加密场景下的使用
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^^^^^^^^^^^^^^^^
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JPEG 编解码器通过 2D-DMA 搬运数据，而 JPEG 编解码器 **无法处理已加密的数据**。因此在开启 PSRAM 加密时，需要让 JPEG 的输入/输出缓冲区位于非加密的内存区域，否则编解码会失败。
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为支持加密场景，驱动程序做了如下处理：
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- 当启用 ``CONFIG_SPIRAM_ENC_EXEMPT`` 时， :cpp:func:`jpeg_alloc_decoder_mem` 和 :cpp:func:`jpeg_alloc_encoder_mem` 会自动从非加密 PSRAM 区域（``MALLOC_CAP_SPIRAM_NO_ENC``）分配缓冲区。
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- 分配的缓冲区会同时满足 cache 行对齐与 2D-DMA 的字节对齐要求。
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使用时请注意：
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1. 建议始终通过 :cpp:func:`jpeg_alloc_encoder_mem` / :cpp:func:`jpeg_alloc_decoder_mem` 分配缓冲区，以保证对齐与内存区域正确。
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2. 非加密区的大小由 ``CONFIG_SPIRAM_ENC_EXEMPT_SIZE`` 决定。由于 JPEG 缓冲区大小取决于图像分辨率，无法自动预测，需根据实际处理的最大图像自行配置。若该区域不足，分配会失败并打印错误日志，提示增大 ``CONFIG_SPIRAM_ENC_EXEMPT_SIZE``；同时注意该值不能大于等于实际 PSRAM 容量，否则非加密区会被禁用。
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.. _jpeg-kconfig-options:
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Kconfig 选项
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^^^^^^^^^^^^
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- :ref:`CONFIG_JPEG_ENABLE_DEBUG_LOG` 可启用调试日志，但会增加固件二进制大小。
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