從慚愧到一點慰藉

由於終於安裝了家居寬頻，所以多聽咗youtube（真喺聽，唔喺睇），我用的裝置是一部android手機接駁藍芽音箱。

但越聽越多很花時間 (youtube真喺好addictive!) 跟住有人話其實是用快速1.5至2倍速度聽youtube。坦白講，我對聲效的認識仍停留在n年前在大學時讀的Digital Signal Processing, 只是識少少Fast Fourier Transform（其實都唔記得晒），仍覺得加速會將聲音變調而唔好聽。

就即管試下…點解android手機嘅youtube無playback speed選項？上網求救，原來只支援android 5或更新的手機（說來慚愧，我部舊手機只是行android 4.4.4）。但是點解google將playback speed logic放在client side而不是server side呢？再上網找資料，原來google在2017年寫過篇blog解釋此功能，仲話甚麼甚麼time stretching，phase vocoder等…（算罷，我投降喇！）不過文章介紹youtube player是用Sonic library來實施variable playback speed。講番效果，其實真喺唔差，沒有雞仔聲。

我平時是用開audacity做音效editing，就看看audacity有無此功能，原本真是有的，快速版是Change Tempo，慢速版（效果好啲）是Sliding Stretch，後者是用Subband Sinusoidal Modeling Synthesis運算法，我試過效果也不錯，總算有點慰藉。

Zoom來學佛 - 林碧君 (因陀羅網 @ 溫暖人間541期)

疫情影響了很多宗教活動，佛教也不例外，目前法師講經/開示、法會、佛學課程、禪修甚至義工們的互動，很多都改以「Zoom」遙距式舉行。

然而，靠「Zoom」弘法，對傳訊和接收雙方的要求都大幅地提高了— 我們準備好了嗎？

不少機構只是把原來的課程／開示設計原封不動地改為網上直播，兩小時的課就直播兩小時，但沒群眾影響下，觀眾真的可以在電腦前呆坐兩小時嗎？欠缺現場氣氛下，對着顯示屏的專注力和現 場聽課會一樣嗎？如何保證聽課的環境 不會分心？(手機有關嗎？) 就算同樣有中場休息，又如何保證小息完後會繼續？(不少有名的網上教育，例如TED，設計 成片長不超過二十分鐘是有原因的。)

講者的挑戰則更大，除了要學習「網紅式」鏡頭表達技巧外，因為無法從現場的反應中，感受到聽眾的接受 程度及最關心的事，便無法調整講授內容 — 容易流於自說自話。

更重要是，聽眾常覺得網上的開示「必然會」重播，便會想「無須即時同 步聽課,日後有空才看」一而「有空 的一日」，永遠是明日。

From Uncertainty Principle to the Dilemma of Efficiency and Service Quality

Recently, listening to some youtube clips about philosophy triggers my memory of Heisenbery's uncertainty principle learnt in high school:

(standard deviation of position) times (standard deviation of momentum) >= Planck constant / 2

It simply states the more certain of the former implies the more uncertain of the latter.
I nearly forgot. But during work, I more often have to deal with the resource (labour or others) efficiency and customer satisfaction (e.g. wait time). Hey! I remember I have learnt queuing theory for M/M/1 model,

the mean queue time is t = ρ / (1-ρ) where ρ = λ / μ
λ is the rate at which packets arrive at the queue (in packets/second), and
μ is the rate at which packets may be served by the queue (in packets/second)

(sorry I in fact forgot the exact formula but I just copy from Wikipedia)

My main point is this has many similarity with uncertainty principle in the sense that the high efficiency you request, the longer wait time will be resulted.

for efficiency, I can view ρ can serve this role because it is always less than one.

The I redefine inefficiency as λ = 1-ρ, then

t = ρ / (1-ρ) ≈ 1 / (1-ρ) (since ρ≈1)
then t • (1-ρ) ≈ 1 or

t • λ ≈ 1

which is my analogy of the uncertainty principle.