The Science Fiction World of Xueba

"Brother Pang, Brother Pang, what's wrong with you?"

Seeing Pang Xuelin lost in thought, Fatty Liu asked curiously.

Pang Xuelin shook his head and said with a smile: "It's okay, by the way, Brother Liu, when are we going to Shencheng?"

It is now May 20th, and there are still more than three months before Wanyan launches the VCD player in September. I must get the patent for the VCD player within three months.

In addition, you have to earn enough initial start-up capital to open the factory.

As for how to get the money, it depends on the next trip to Shencheng.

Liu Qi said: "Let me arrange it for you first. Without a border defense certificate, I can only find a snake head to smuggle through the second-line customs. I need to find a reliable one. It will take at least two or three days."

Pang Xuelin smiled and said, "Brother Liu, I will trouble you then!"

At noon, the nanny made a Cantonese-style morning tea for everyone. Pang Xuelin had tasted Cantonese cuisine long ago, but he didn't think it was so special.

On the other hand, Mu Donglai and Mu Qingqing, who have been living in the Northwest, are very curious about this pure Cantonese cuisine.

Crystal shrimp dumplings, chicken feet, pork ribs, pork belly, fish porridge, rice rolls, etc. The two people who ate it were full of praise.

After lunch, in the afternoon, everyone watched the LD player in the living room.

All kinds of old versions of Hong Kong films, "The True Colors of a Hero", "A Lang's Story" and so on, let Pang Xuelin experience the feelings of Hong Kong films born in the 1980s.

Mu Qingqing, Mu Donglai and Fatty Liu all watched with great interest, but Pang Xuelin was not very interested.

He was a post-1995 generation, and Hong Kong movies have declined since he can remember. Coupled with the era of mobile Internet in the later generations, the aesthetics have been greatly improved. Although these movies are classics, they are no longer in line with Pang Xuelin's taste.

The next morning, Fatty Liu and Mu Donglai went out.

Fatty Liu said that he would go to a friend to arrange for Pang Xuelin to pass the test.

As for Mu Donglai, he went out to visit his friends at Sun Yat-sen University.

"Brother Pang Da, we have nothing to do today, do you want to go out for a stroll?"

Mu Qingqing changed into a chiffon short-sleeved dress,

Stepping on small leather boots, her jet-black hair was tied into two beautiful braids, extending from the forehead on both sides to the back of the head, looking clean, fresh and beautiful.

This girl also belonged to Bai Fumei in this era. She was born in a Kochi family. She was taught strictly since she was a child.

Pang Xuelin actually knew Mu Qingqing's thoughts very well, but he didn't care too much.

He is very clear that he will leave the earth sooner or later, so in this world, Pang Xuelin has no idea of ​​falling in love and starting a family.

As for Mu Qingqing's feelings, in his opinion, it was more because of the psychological shock of suddenly appearing in front of her that night at her most desperate moment, which made her feel attached to himself.

Anyway, she is going to Xiangjiang to study in university next time. As time goes by, such feelings will gradually fade away.

Looking at Mu Qingqing's expectant eyes, Pang Xuelin laughed and said, "Okay, where do you want to go?"

Mu Qingqing smiled and said, "Brother Pang Da, I will go wherever you go."

Pang Xuelin thought for a while and said with a smile, "Okay, then let's go to Yangcheng Computer City today."

"Yangcheng Computer City?"

Mu Qingqing's eyes lit up.

In this era, digital products have just begun to show their brilliance in the country. Regardless of boys and girls, they are very interested in computers and the like. Naturally, many girls in later generations will not be indifferent to digital products.

Not to mention, Mu Qingqing herself is a master of science.

The two went downstairs together, and Huang Mao, who was guarding the shop, came up to meet him, nodded and bowed his head and said, "Brother Lin, Sister Qingqing, where are you going? I'll take you there."

Pang Xuelin said with a smile: "Huang Mao, do you know where the Yangcheng Computer City is?"

Huang Mao was slightly taken aback, and said: "I know, Yangcheng Computer City is not far from here, follow this road and pass two intersections, turn right onto Tianhe East Road, and you can walk there in about ten minutes."

Mu Qingqing said: "Brother Pang Da, since it's so close, let's walk there, there's no need to send it off."

Pang Xuelin smiled and said: "That's fine, Huang Mao. If Professor Mu or Lao Liu comes back, you can tell them that Qingqing and I went to the computer city."

"Okay! Brother, then go slowly!"

Looking at the backs of Pang Xuelin and Mu Qingqing going away, Huang Mao couldn't help feeling a little envious.

At this moment, behind him, another employee from Liu Qi's shop stepped forward and said, "Brother Huang Mao, that's the sister Qingqing you mentioned? She's so pretty, that pretty girl is so lucky..."

Huang Mao patted him on the head and said: "Stinky boy, don't think too much, do you know who that handsome boy is?"

"who is it?"

Huang Mao said: "Did you read the news in southern Hunan two days ago? It said that the police destroyed a group of railway bandits and seized many gunpowder guns and axes."

The young man asked curiously: "Brother Huang Mao, what's the matter? Is it related to that handsome boy?"

"Don't be so pretty, so pretty, you'll call him Brother Lin when you see him. The gang of robbers was taken care of by him alone. I heard that when they robbed the train, there were more than a dozen people, not only with guns, but also with explosives. I was taken aback." Killed by Brother Lin alone."

"real or fake?"

"Then it can be fake, it's all seen by the blue eyes of the boss, otherwise why would the boss flatter others."

"Hey, you're right!"

...

Naturally, Pang Xuelin didn't know that he had become the object of Huang Mao's gossip.

He and Mu Qingqing strolled on the streets of Yangcheng, Mu Qingqing jumped up and down happily like a lark.

Many people passing by turned their attention to the pair of boys and girls.

Although Mu Qingqing was the focus of attention, Pang Xuelin in a simple T-shirt and jeans was no less impressive.

Pang Xuelin is not bad in appearance, and he has experienced the tempering of many worlds. He has a faint scholarly temperament and a wild charm at the same time.

Otherwise, Mu Qingqing wouldn't have fallen in love with him at first sight.

After all, any form of love at first sight is nothing more than love at first sight.

If Pang Xuelin grew up to look like Fatty Liu, Mu Qingqing would at most be grateful to him, and would not have the tendency to fall into it like now.

In front of the computer city, Pang Xuelin did not see the scene of the digital city, which was full of traffic and crowds before the rise of e-commerce, but seemed a little deserted.

Yangcheng Computer City was established not long ago. It is a pioneer in the digital professional market in South China. There are maintenance departments of various digital product brands, various compatible machines, electronic parts, genuine software, consumables, etc. inside.

After the two entered, Pang Xuelin didn't go straight to the brand stores set up by those computer brand manufacturers, but walked around inside first, and then stopped in front of a relatively small electronic product consumable store.

"Brother Pang, are you going to buy a computer?"

Mu Qingqing asked curiously.

Pang Xuelin shook his head with a smile and said, "I'll just buy some parts."

As he said that, he walked up and said to the owner of the consumables store who was sitting idly by the counter: "Boss, do you have a CD-ROM drive here?"

The boss was slightly taken aback, and said with some doubts: "Young man, why do you want that thing?"

Pang Xuelin said with a smile: "The CD-ROM drive of my computer is broken, and I am going to change it myself."

The boss pondered for a moment, then said: "Yes, there is, but the price is not cheap, it costs more than five hundred. If you change it yourself, if it doesn't work, I won't return it."

Pang Xuelin smiled and said: "Don't worry, I will install it myself. In addition, do you have a pen and paper, I still have some parts to list, including DSP chips, diodes, triodes, resistors, capacitors, power transformers and some small servos and so on..."

The boss was stunned, found a pen and paper and handed it to Pang Xuelin, curiously said: "Young man, what do you want these things for?"

Pang Xuelin smiled and said, "Do a small experiment."

Next, without saying much, Pang Xuelin wrote down a series of dense lists on paper and handed them to the owner of the consumables store.

The owner of the consumables store was a little surprised. Only a professional electronic engineer could understand many of these things. Some things were not even familiar to him. Who is this high school boy in front of him?

Seemingly seeing the curiosity of the consumable store owner, Pang Xuelin said with a smile: "I am a graduate student majoring in electronic information engineering at Sun Yat-sen University, and I will help my tutor buy something by the way."

"It turned out to be a top student of CUHK."

The owner of the consumables store was relieved immediately, and said with a smile: "Liangzi, the parts you listed here total about 1,200 yuan. The deposit, come to pick it up tomorrow, I'll get it all together for you today, okay?"

"no problem!"

Pang Xuelin laughed, and readily took out 500 yuan and handed it to the boss, who wrote a receipt and pick-up list and returned it to Pang Xuelin.

Twenty minutes later, Pang Xuelin and Mu Qingqing came out of the computer city, and Mu Qingqing was still a little dizzy.

"Brother Pang, what are you buying these things for?"

Like the boss, Mu Qingqing also couldn't understand Pang Xuelin's purpose.

Pang Xuelin laughed and said, "I can't tell you how to make a small toy for a while, anyway, you will know it in two days."

"oh!"

Mu Qingqing nodded with a half understanding.

Pang Xuelin gave her a very mysterious feeling.

Born as an orphan, he has super fighting power, is handsome, has an extraordinary bearing, and his knowledge is so extensive that even his father, who is a university professor, is amazed at him.

Therefore, although Mu Qingqing didn't want to understand Pang Xuelin's knowledge of so much electronics, she was soon relieved.

Anyway, Pang Xuelin is an omnipotent existence in her heart, is it strange to have some new skills?

Naturally, Pang Xuelin didn't know what Mu Qingqing was thinking. He was going to make a VCD prototype.

In fact, after the emergence of MPEG technology, VCD technology has been fully mature.

The so-called MPEG refers to image compression technology.

Before the appearance of MPEG technology, the amount of video image data after digitization was astonishing. If the original video image data was not compressed, only 20 seconds of medium-resolution color digital images could be stored on a 12-centimeter optical disc of 650 megabytes. video image.

And MPEG technology, you can compress and encode the moving video images of 30 frames or 25 frames per second and their stereo audio signals, and write them into CD discs, making a VCD disc with the same size as ordinary CD discs. , can play 74 minutes of video programs continuously, its image quality is much better than that of VHS video recorder, and its sound quality reaches the effect of CD laser sound.

The fundamental reason why MPEG image compression can be realized is that the original image has a large degree of information redundancy, such as TV images. There is a large spatial correlation between adjacent pixels of this type of image, and there is also a large gap between the front and rear frames. large time dependence.

The MPEG compression algorithm first preprocesses the video image with a resolution of 704×408 or 704×576 recommended in the CCIR601 standard. The compression is to reduce the pixels in the horizontal and vertical directions by half and become a SIM of 352×240 or 352×288. image format.

This is followed by further compression through two main techniques, Discrete Cosine Transformation and Motion Compensation.

The discrete cosine transform technology based on 8×8 sub-blocks can reduce the spatial redundancy, and the fast motion compensation technology based on 16×16 can reduce the temporal redundancy.

For the inter-frame prediction error, discrete cosine transform can be used to achieve the purpose of further compressing the data.

At the same time, the MPEG compression standard also takes advantage of the physiological characteristics that the human eye is sensitive to image brightness information but not to color information, and adopts a double brightness sampling scheme, that is, every four-bit brightness value is generated, only two-bit chrominance values ​​are generated .

In the end, this algorithm can achieve a data compression ratio of 1/50 to 1/200.

In addition, this algorithm also uses the basic principle of acoustic psychology, that is, audio at certain frequencies cannot be heard when audio at other frequencies is present, which is the shielding filter function of the human ear.

In this way, the MPEG audio compression system can remove unwanted audio signals that are completely or largely inaudible to humans.

The audio signal whose sampling frequency is 44.1k Hz can be compressed to 1/8 without obvious distortion of the sound quality. It is difficult for ordinary users to distinguish the difference between the sound quality of the MPEG system and the standard CD.

At present, the international MPEG compression technology has been fully mature, and the rest is how to write the video information into the CD, and re-decode it into a video signal and broadcast it on the TV.

And there are two core technologies needed here, one is the laser reading probe technology commonly used on CDs, and the other is video decoding chip technology.

At present, the laser reading probe technology is mainly in the hands of Philips and Sony, which is why Pang Xuelin bought a CD-ROM drive, because it comes with a laser reading probe.

In later generations, there are many DIY enthusiasts on the Internet who converted CD-ROM drives into VCD players.

The principle is to take the signal picked up by the laser head assembly on the optical drive from the VCD video disc, and after being processed by the digital signal processing chip DSP, the RF signal is output from the RF pin of the radio frequency, and the RF signal is sent to the added VCD decompression chip for processing. , output video and audio signals.

The only troublesome thing is that there is no dedicated video decoding chip for VCD.

Pang Xuelin could only temporarily design a video decoding chip with various small integrated circuits to output video signals.

That's why he buys so many small electronic components.

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