Restrictions

For the Atlas training products , this function is reserved and is not supported currently.

Resolution Restrictions

Input image resolution range
During image processing by VPC, the general input resolution ranges from 10 x 6 to 8192 x 8192. The resolution restrictions of some APIs may be different. For details, see the API descriptions in VPC APIs. When the input image format is YUV440SP or YUV440P, the maximum width of the image is 4096.

Output resolution range:

Product	Resolution Range
Atlas inference products	10 * 6 ~ 4096 * 4096
Atlas A2 training products / Atlas A2 inference products Atlas 200I/500 A2 inference products Atlas A3 training products / Atlas A3 inference products	10 * 6 ~ 4096 * 8192

Product

Resolution Range

Atlas inference products

10 * 6 ~ 4096 * 4096

Atlas A2 training products / Atlas A2 inference products

Atlas 200I/500 A2 inference products

Atlas A3 training products / Atlas A3 inference products

10 * 6 ~ 4096 * 8192

Restrictions on Buffer Allocation and Freeing APIs

For details about the requirements on the input and output buffer sizes, see the calculation formulas in Restrictions on Image Formats, Width and Height Alignment, and Buffers.

Test Object	Buffer Allocation/Freeing API
Atlas inference products	During image processing by VPC, acl.himpi.dvpp_malloc and acl.himpi.dvpp_free are called to allocate and free the input and output buffers on the device. The buffer lifetime is managed by the user.
Atlas A2 training products / Atlas A2 inference products Atlas 200I/500 A2 inference products Atlas A3 training products / Atlas A3 inference products	During image processing by VPC, the following two types of buffer allocation/freeing APIs are supported: Allocate or release the input and output buffer on the device by calling acl.rt.malloc\acl.rt.free. The life cycle of the buffer is managed by the user. Allocate or release the input and output buffer on the device by calling acl.himpi.dvpp_malloc\acl.himpi.dvpp_free. The life cycle of the buffer is managed by the user. acl.himpi.dvpp_malloc allocates a dedicated buffer for processing media data. However, the address space of the dedicated buffer is limited. If buffer planning is cared or buffer resources are limited, you are advised to allocate buffer by calling acl.rt.malloc.

Test Object

Buffer Allocation/Freeing API

Atlas inference products

During image processing by VPC, acl.himpi.dvpp_malloc and acl.himpi.dvpp_free are called to allocate and free the input and output buffers on the device. The buffer lifetime is managed by the user.

Atlas A2 training products / Atlas A2 inference products

Atlas 200I/500 A2 inference products

Atlas A3 training products / Atlas A3 inference products

During image processing by VPC, the following two types of buffer allocation/freeing APIs are supported:

Allocate or release the input and output buffer on the device by calling acl.rt.malloc\acl.rt.free. The life cycle of the buffer is managed by the user.
Allocate or release the input and output buffer on the device by calling acl.himpi.dvpp_malloc\acl.himpi.dvpp_free. The life cycle of the buffer is managed by the user.

acl.himpi.dvpp_malloc allocates a dedicated buffer for processing media data. However, the address space of the dedicated buffer is limited. If buffer planning is cared or buffer resources are limited, you are advised to allocate buffer by calling acl.rt.malloc.

Restrictions on Image Formats, Width and Height Alignment, and Buffers

To implement VPC functions with related APIs:

For details about the definition of the image format, see hi_pixel_format. For details about the concepts such as width stride and height stride, see Terminology.
The minimum and maximum values of the width stride and height stride vary with different versions:
- Atlas inference products : The width stride ranges from 32 to 16384 (4096 x 4). For a 4096-pixel ARGB image, one pixel occupies four bytes, and a line of pixels occupies 4096 x 4. The height stride ranges from 6 to 16384.
- Atlas 200I/500 A2 inference products : The minimum width stride is 10 and the minimum height stride is 6.
- Atlas A2 training products / Atlas A2 inference products : The minimum width stride is 10 and the minimum height stride is 6.
- Atlas A3 training products / Atlas A3 inference products : The minimum width stride is 10, and the minimum height stride is 6.
Different APIs may have different requirements on image formats. For details, see the API descriptions in VPC APIs.

**Table 1** **Restrictions on the input image format, width and height alignment, and buffer size**
Product	Image Format	Width and Height	Width Stride x Height Stride Alignment Atlas inference products	Width Stride x Height Stride Alignment Atlas 200I/500 A2 inference products Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	Buffer Size (in Bytes)
General format, supported by all versions	YUV400 8-bit	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16. Height stride: No alignment requirement. The value is the same as height.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	YUV420SP NV12 8-bit YUV420SP NV21 8-bit	Width: Must be a multiple of 2. Height: Must be a multiple of 2.	Width stride: Round up the width to the nearest multiple of 16. Height stride: Round up the height to the nearest multiple of 2.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 3/2
	YUV422SP 8-bit YVU422SP 8-bit	Width: Must be a multiple of 2. Height: No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16. Height stride: No alignment requirement. The value is the same as height.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 2
	YUV444SP 8-bit YVU444SP 8-bit	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16. Height stride: No alignment requirement. The value is the same as height.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 3
	YUV422 Packed YUYV 8-bit YUV422 Packed UYVY 8-bit YUV422 Packed YVYU 8-bit YUV422 Packed VYUY 8-bit	Width: Must be a multiple of 2. Height: No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16 and multiply the result by 2. Height stride: No alignment requirement. The value is the same as height.	Width stride: Width x 2. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	YUV444 Packed 8-bit RGB888 BGR888	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16 and multiply the result by 3. Height stride: No alignment requirement. The value is the same as height.	Width stride: Width x 3. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	ARGB8888 ABGR8888 RGBA8888 BGRA8888	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16 and multiply the result by 4. Height stride: No alignment requirement. The value is the same as height.	Width stride: Width x 4. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	YUV440SP 8-bit YVU440SP 8-bit	Width: No alignment requirement, but the width must be ≤ 4096. Height: Must be a multiple of 2.	Width stride: Round up the width to the nearest multiple of 16. Height stride: Round up the height to the nearest multiple of 2.	Width stride: No alignment requirement. The value is the same as width. Height stride: Round up the height to the nearest multiple of 2.	Width stride x Height stride x 2
Only the following versions support this format: Atlas 200I/500 A2 inference products Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	YVU420 Planar YUV420 Planar	Width is 2-pixel aligned; height is 2-pixel aligned.	-	Width stride: Has no alignment requirements but must be the same as width. Height stride: Has no alignment requirements but must be the same as height.	Width stride x Height stride x 3/2
	YVU422 Planar YUV422 Planar	No alignment requirement.	-	Width stride: Has no alignment requirements but must be the same as width. Height stride: Has no alignment requirements but must be the same as height.	Width stride x Height stride x 2
	YVU444 Planar YUV444 Planar	No alignment requirement.	-	Width stride: Has no alignment requirements but must be the same as width. Height stride: Has no alignment requirements but must be the same as height.	Width stride x Height stride x 3
	YVU444 Packed 8-bit	No alignment requirement.	-	Width stride: No alignment requirement. Width stride = Width x 3. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	YUV440 Planar YVU440 Planar	Width: No alignment requirement, but the width must be ≤ 4096. Height: Must be a multiple of 2.	-	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 2
	RGB888 Planar BGR888 Planar	No alignment requirement.	-	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 3
Only the following versions support this format: Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	YUV400 FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride
	RGB888 FP32 BGR888 FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 3 x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride
	RGB888Planar FP32 BGR888Planar FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride x 3

**Table 2** **Restrictions on the output image format, width and height alignment, and buffer size**
Product	Image Format	Width and Height	Width Stride x Height Stride Alignment Atlas inference products	Width Stride x Height Stride Alignment Atlas 200I/500 A2 inference products Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	Buffer Size (in Bytes)
General format, supported by all versions	YUV400 8-bit	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16. Height stride: No alignment requirement. The value is the same as height.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	YUV420SP NV12 8-bit YUV420SP NV21 8-bit	Width: Must be a multiple of 2. Height: Must be a multiple of 2.	Width stride: Round up the width to the nearest multiple of 16. Height stride: Round up the height to the nearest multiple of 2.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 3/2
	YUV422SP 8-bit YVU422SP 8-bit	Width: Must be a multiple of 2. Height: No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16. Height stride: No alignment requirement. The value is the same as height.	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 2
	YUV444 Packed 8-bit RGB888 BGR888	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16 and multiply the result by 3. Height stride: No alignment requirement. The value is the same as height.	Width stride = Width x 3 Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	ARGB8888 ABGR8888 RGBA8888 BGRA8888	No alignment requirement.	Width stride: Round up the width to the nearest multiple of 16 and multiply the result by 4. Height stride: No alignment requirement. The value is the same as height.	Width stride = Width x 4 Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
Only the following versions support this format: Atlas 200I/500 A2 inference products Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	YUV422 Packed YUYV 8-bit YUV422 Packed UYVY 8-bit YUV422 Packed YVYU 8-bit YUV422 Packed VYUY 8-bit	Width: No alignment requirement. Height: Must be a multiple of 2.	-	Width stride = Width x 2 Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
Only the following versions support this format: Atlas 200I/500 A2 inference products Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	YVU444 Packed	No alignment requirement.	-	Width stride = Width x 3 Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride
	RGB888 Planar BGR888 Planar	No alignment requirement.	-	Width stride: No alignment requirement. The value is the same as width. Height stride: No alignment requirement. The value is the same as height.	Width stride x Height stride x 3
Only the following versions support this format: Atlas A2 training products / Atlas A2 inference products Atlas A3 training products / Atlas A3 inference products	YUV400 FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride
	RGB888 FP32 BGR888 FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 3 x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride
	RGB888Planar FP32 BGR888Planar FP32	No alignment requirement.	-	The width stride does not need to be aligned. The width stride is the value of width x 4 (4 indicates that FP32 occupies four bytes). The height stride does not need to be aligned and must be the same as the height.	Width stride x Height stride x 3

Restrictions on Image Cropping and Pasting

The crop ROI must not be larger than the input image.
The restrictions on the odd and even numbers of the crop and paste ROIs are as follows:
If the output image is in YUV420SP format, the left offset and top offset of the paste ROI must be even numbers, and the right offset and bottom offset must be odd numbers.

If the output image is in YUV422SP format, the left offset must be an even number and the right offset must be an odd number.

For other formats, there are no such limits.
The paste ROI must not be larger than the output image. A maximum of 256 paste ROIs are supported.
Due to the 16-pixel alignment requirement, there are the following restrictions for the Atlas inference products :
- The left offset of the paste ROI relative to the output image is 16-pixel aligned. The paste ROI can be directly aligned on the leftmost side of the output image, that is, with zero left offset relative to the output image. Zero also meets the 16-pixel alignment requirement.
- It is recommended that the pasting width of the output image be a multiple of 16. Otherwise, an extra segment of invalid data is padded. As shown in Figure 4 and Figure 5, the green box indicates invalid data.
- For resizing with the aspect ratio preserved, the left offset for pasting must be a multiple of 16. Therefore, the acl.himpi.vpc_crop_resize_paste call may result in paste ROI deviation from the center of the output image. In this case, you can add the acl.himpi.vpc_crop_resize_make_border or acl.himpi.vpc_batch_crop_resize_make_border call to implement the cropping, resizing, and padding functions together.

Restrictions on Downsampling of YUV Images

VPC converts the input image format to YUV444 or RGB for internal processing based on the input or output image format. YUV444 or RGB output format has no restriction on the odd and even numbers of the width and height, while the YUV420SP or YUV422SP output format, which performs downsampling processing, has such restrictions due to the data format. Therefore, abnormal data may exist on the output image boarders.

Figure 1 Example of abnormal images

The root cause is that during the calculation, when the output image is at an odd start point, the image is correct for the YUV444 format. However, when the YUV420SP format is downsampled, the odd and even lines share the same UV. In this case, the Y of the start line and the UV of the previous line form a new pixel and abnormal data is generated.

Accuracy Restrictions ( Atlas inference products )

For the VPC function, the width of the paste ROI must be a multiple of 16. Otherwise, the paste ROI may contain invalid data for padding. In this case, you can resize the valid ROI to a multiple of 16 x 2 before pasting or use AIPP to crop the valid ROI and remove invalid data to ensure inference accuracy.

Parent topic: VPC APIs