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OMAP3 based video decoder

In Electronic Infomation Category: O | on April 23,2011

Platform, for the QCIF (standardized image format commonly used), 15 fps applications, the power in the 9.9 ~ 28.5mW. Time for common mobile phone 650 mAh battery can work continuously for about 34 to 59 hours, which is obviously general enough for application. The TIs another dedicated multimedia processor chip DM642, the power consumption of 1.5W, is 50 to 150 times OMAP. For portable multimedia terminals, since the operation does not require high processing power, using OMAP platform can satisfy the need, and LM2907N-8 datasheet and can save battery power.

speed considerations. TMS320C64X + up to 8 instructions can be executed in parallel, so the theoretical maximum speed is 4 160 MIPS (520MHz). This is compared to the fastest multi-media processor chip DM642 (4 800 MIPS, 600 MHz) is slightly lower, but the difference between the target location. DM642 is mainly used for real-time encoding speed is higher on the occasion, and LM2907N-8 price and 0MAP handheld devices mainly used for decoding. Base Profilc H.264 algorithm with an example, the complexity of the MPEG-4 higher than the 20% to 30%. For MPEG4, in QCIF, 15 fps required under 28 MIPS; H.264 algorithm corresponding to the requirements of 40 MIPS Base Profile computing speed.

program structure considerations. DSP on-chip memory, the fastest, but very limited, so must the data into the memory chip. As the current encoding all the macro block based on each macro block up to 16 16, it is more common approach is to use, DMA mode data that will be used to advance into the chip. DMA transfer speed quickly, so it can also be a serial parallel transmission.

software speed up consideration. The preparation of the rules can be modeled IMGLIB in assembly language rewriting part of the most time-consuming, combined with TIs data sheet for C-level and LM2907N-8 suppliers and assembly-level program optimization. The TI compiler compiler efficiency the company has been increasing, the general and readability perspective, recommend the use of C language.

3 real-time video decoding software on the OMAP Development process on the OMAP

usually divided into two parts: ARM side responsible for the control and display; DSP for data processing side. Provided by TI DSP development tools at both ends, respectively, in the development of CCS, the video decoding process shown in Figure 2.

ARM-side: initialized the OMAP3530 chip, including the ARM, DSP, TC and other clock settings, DSPs turn off and reset, LCD, timers and other peripheral initialization. After the start, ARM core has been a particular query in the shared memory flag, when the query to a decoding end, to start the LCD dedicated DMA, the LCD on the show.

DSP-side: responsible for compression decoding. Placed in the compressed stream in SDRAM. PC-based decoding process with the main difference is that, due to limited memory, DSP chip, it can not be the current frame and reference frames are on the chip, so the macro block as a unit with on-chip SDRAM memory in the data between delivery. Moreover, as displayed on the LCD screen when the need to convert RGB images, so in the end of each frame to be transferred through the YUV to RGB real-time display.

4 results

0MAP3530 platform implemented in the AVS decoder, Table 4 shows the experimental data on the OMAP3530.

Conclusion

TI architecture of the companys 0MAP openness is good, in this architecture to facilitate porting, prepared for the multi-media platforms. More and more manufacturers use as a mobile multimedia video OMAP chip carrier, OMAP and the combination of the popular video standard in mobile communications and multimedia signal processing will also have a good prospect.

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