Vertical Bit Map Coding

A. Introduction

For recording my research in audio bit plane coding technique, here I demonstrate a series of decoded results produced by a fine-scalable lossy-to-lossless audio coder. The key idea is quite simple but effective. From my doctoral study, I learned the significant map (the most significant bits of all coefficient to be encoded) plays a critical role in both coding efficiency and audio quality. If I can use as less bits as possible to encode the significant map, then the decoded quality will be as good as possible even in a very low bitrate. Unlike the scalable audio coder, Harmonic Quad Tree coding (HQT), in my doctoral thesis, this coder explores the relationship between the most significant bits of two adjacent frequency coefficients, not harmonic relationships among frequency coefficients. In addition, the bit plane coding technique, Set Partitioning In Hierarchical Trees (SPIHT), is absent in the new coder. I would like to named this coder as Vertical Bit Map coding (VBM) at this moment.

B. Experiment

The chosen test audio piece is from "castant" which is a famous test material for audio compression. Due to its rich and fast claps, the audio artifact so called "pre-echo" can be easily perceived after lossy compressed.

The following two examples show an interesting function I called it variable bitrate playback. To make you quickly understand this function, I decoded the bitstreams according a series of specified varying bitrates frame by frame and drawn their spectrum. The figures have the original spectrum in the top, the decoded spectrum in the middle, and the specified varying decoding bitrate of each frame in the bottom.

The first experiment is set the varying bitrate from 16kbps to 64kbps in a step size of 2kbits.

The second experiment is set the varying bitrate from 32kbps to 64kbps in a step unit of 1kbits.
The audio qualities are very defective because these two experiments are extraordinary only for demonstration. In an usual scenario, the varying decoding bitrate is expected to change in a smooth way. For keeping acceptable audio quality, the decoding bitrate would not be allowed to adjust so frequently and amplify so large range in a short time.

C. Summary

As a conclusion and a reminder for myself, this VBM coder is an experiment of my speculation in the importance of significat map in audio coding. This VBM audio coder can be categorized as:
1. Fine-scalability: scalable grain is downto 1 bit,
2. Lossy-to-lossless: the embedded bitstream contains all possible playback bitrates, even the archive,
3. Low complexity: there are very few prediction calculations and history storages in analyzing and reconstucting the significant map. Therefore it can be claimed that complexity is equivalent and low in both encoding and decoding,

and has the following features:
1. Encode once, decode many time,

2. Variable bitrate playback: by indicating the decoding bitrate of every frame, decoder can achieve variable bitrate playback in frame scale,
3. Real-time encoding and decoding.

It is noted that the VBM coder has NO
1. Psychoaoustic model: there is no perceptual controlling in the current implement,
2. Window switch: there is no attack detection to control long/short window switch. Yes, there is one single frame size.

無薪假打破最低薪資標準

昨天行政院勞工委員會以新聞稿方式，間接同意勞資協議「無薪休假期間，月薪可低於1萬7280元」。無薪假期間，可以不用管最低薪資標準，是完全站在資方立場在考慮事情了，這樣把員工自己逼走還不用付遣散費，如此資方還真好幹，連預先精算成本都不用了，老實說，資遣費也該是在營運成本考量內，如果不需要這麼多人力了，就放了勞工吧!對景氣預測及營運的失誤不該歸責於非管理階層，遊戲規則都明明白白的在那裏，風險跟獲利該完全地成比例，沒道理要保障企業一定獲利吧!
對於政府而言，我只能說：真奇怪，如果市場就在那裏，幾家公司的關門根本無關痛癢，因為一定會有新的公司出來賺市場的錢，保障勞工才是保護未來產業再起的正道，因為勞工的技術還在，只不過是換了一批資方而已。

活在當下

人類奇妙的地方之一就是發達的大腦，會有個想像中的世界，一個想像中的自己，就像現代電腦中的虛擬實境，人總是不斷地在腦中模擬現實環境，模擬應該有的反應。忘記什麼時候開始，現實跟想像分道揚鑣，腦袋中的時間流動似乎變得非常慢，而現實時間開始相對變快；開始感覺時間流逝飛快，是從當兵期間發生的，在新兵訓練時，時間的單位是十五分鐘，可是下部隊之後，時間的單位是一次次的放假。從此，一天一天就像翻書頁一樣地快速，在想像中憂慮於光陰虛度的同時，在現實中卻也完成了許許多多的事，真是一種難以言喻的感覺。