Shaojun Wang

JPEG hardware decode and resize in i.MX6

Discussion created by Shaojun Wang Employee on Jan 17, 2014
Latest reply on Sep 7, 2015 by yong tang

MX6 VPU can support baseline JPEG decode and encode. This demo show how to use VPU to decode baseline JPEG and how to use G2D to convert, crop and resize the VPU output image.

The BSP version in this demo is L3.0.35_4.1.0.


1. VPU decode

1.1 VPU lib patch

VPU can support JPEG decode and downscale, the downscale rate is 0, 1/2, 1/4 and 1/8.

0001-support-jpeg-downscale-in-vpu-lib.patch: VPU lib patch to support JPEG decode and downscale.

Run below step to extract VPU lib source code from ltib, apply patch and build new VPU lib

$ ./ltib -m prep -p imx-vpu

$ Apply 0001-support-jpeg-downscale-in-vpu-lib.patch to ltib/rpm/BUILD/imx-vpu-lib-3.0.35-4.1.0

$ ./ltib -m scbuild -p imx-vpu

$ Update ltib/rpm/BUILD/imx-vpu-lib-3.0.35-4.1.0/ to your rootfs.


1.2 Kernel patch

When run stress test, VPU may not get DMA buffer. The decode would failed.

0001-VPU-Reserve-64MB-physical-memory-for-VPU.patch can fix the memory allocate failed issue, it reserve 64MB physical memory for VPU.


1.3 JPEG file size and VPU output image size

In L3.0.35_4.1.0, CONFIG_FORCE_MAX_ZONEORDER is set to 14, so the max DMA buffer size is 2^(14-1)*4094=32MB.

If your Kernel CONFIG_FORCE_MAX_ZONEORDER is less than 14, please modify STREAM_BUF_SIZE in mxc_jpeg_test/jpeg_test.h to the correct value.

In VPU lib, two DMA buffers are allocated, one is input buffer, for JPEG source file; the other is output buffer, for VPU output raw image. So the JPEG file size should not larger than 32MB. This demo use VPU downscale function to limit output image size to less than 32MB.


2. G2D

Since VPU output format is YUV, to show the image to display, need to convert the format to RGB and resize.

This demo use G2D to do the conversion. Make sure gpu-viv-bin-mx6q is built into your rootfs.

About more information of G2D, please refer to i.MX_6_G2D API.pdf.

In ltib, extract GPU lib by

$ ./ltib -m prep -p gpu-viv-bin-mx6q


3. Build the demo

In mxc_jpeg_test/Makefile, modify INC and LFLAGS to point to the correct path of Linux kernel, VPU lib and GPU lib, then run below command

$ export CROSS_COMPILE=/opt/freescale/usr/local/gcc-4.6.2-glibc-2.13-linaro-multilib-2011.12/fsl-linaro-toolchain/bin/arm-none-linux-gnueabi-

$ make clean; make


4. Run the demo

4.1 Get help of this demo

$ ./mxc_jpeg_test.out -H

4.2 Decode and display in a window

$ ./mxc_jpeg_test.out -D "-i 1.jpg -w 640 -h 480 -l 200 -t 200"

4.4 Enable zoom and drag effect on small window, rotate 90

$ ./mxc_jpeg_test.out -D "-i 1.jpg -z 29 -w 320 -h 240 -l 200 -t 200 -r 1"


5. VPU limitation

5.1 There are two kinds of JPEG format, Baseline and Progressive. VPU only support Baseline format.

5.2 VPU can’t decode JPEG file with width or height larger than 8192

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