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[#1] Blogs: 數碼音樂重播專欄 (1)    

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數碼音樂重播專欄 (1)


數碼音樂重播專欄 (1)

數碼音樂重播專欄 - 序

15 年沒有執筆寫音響專欄,音響產品的改變不大,音響市場及用家心態卻變了不少。 由 1982 CD 鐳射唱片 (Compact Disc) 推出後,數碼化的音樂和影像已經在市塲 30 年,和我們生活結合。 現在提起電話,打開電視,每天上 facebook, 微博,email 都是數碼化的世界。 由今期開始,筆者希望跟各位分享數碼音樂世界的發展,其中可能是最新技術,也可以是基本認識,甚至是高解像錄音下載,軟硬兼備。 希望這專欄可以多點互動,所以歡迎大家把問題直接電郵至 chinamastering@gmail.com


CAS - Computer As Source

先講音響潮語,這 CAS 不是 ”民安隊”,是由 ”電腦作為訊源” 之解。

電腦及數碼科技的進步,今天愈來愈多樂迷及音響發燒友已採用電腦作為他們的音響播放方式。 當中涉及軟體應用和硬體選擇,五花百門。 用電腦播音樂有幾多好處,有幾多問題出現,會是今後探討分析的重點。


傳統的 CD 播放形式

CD 機播放 CD 可能並不是新鮮事。 由最早期 14bit CD 機至現在大多數 CD 機都配備 24bit / 96kHz 甚至 192kHz 的內部解碼功能。 重點是只要是播放 CD 的,都只擁有 16bit / 44.1kHz 的質數。 音響市場我們常見寫在唱片上的 24 / 96 錄音、192kHz 錄音,其實在製作 CD 過程中,都會被迫打回 CD 制式 - 16bit / 44.1kHz。 這點是現在至未來也改變不了的事實。


高解像錄音 -> CD

筆者第一個 24/96 錄音大約在 1995 年中生產。 由高解像錄音轉回 CD 這過程中,當中有涉及高深數碼學問,但是跟高清音源還有很大差距。 最佳例子便好像高清影像在 Bluray 跟 DVD 的分別。 15 年來我都希望把錄音中最好的質數帶給音響愛好者。 筆者獨立製作的 ”爵士原音” 三部曲便是由 CD -> SACD -> HiRes 所進發。


甚麼是 Bit Depth / 甚麼是 Sampling Rate?

數碼電腦世界並沒有分開音樂、影像、文字。 在電腦語言來說, 所有內容都是由 ”0”  和 ”1”  組成的二元位文字 ( binary number)。 在我們十進制的 ”10”,在二元位文字便是 ”1010”。 未來在 CAS 內容,我們將多次談及二元位文字,所以希望大家多關注。

Binary 二元位 0 1 10 11 100 101 110 111 1000 1001 1010
Decimal 十進制 0 1 2 3 4 5 6 7 8 9 10

數碼 CD 音樂儲存 16bit 代表了有 16 個元位的字元長度 (Word length)。 最大可代表的數字便是 “1111 1111 1111 1111 1111 1111 1111 1111” = 十進制的 ”65536”。 一個真正 24 元位錄音最大可儲存十進制的 “16777216” 數字,簡單來說是較 16bit CD 格式高 256 倍的細節儲存度。 用聲學語言來講,每一 Bit 數碼字元大約可儲存 6dB 動態,CD 格式可有 96dB 動態,而 24bit 格式便擁有 144dB 動態。


Sampling Rate (取樣率)?

由著名 Harry Nyquist 和 Claude Shannon 的基本通訊學理論,把一個訊號以數字化表示。 Nyquist-Shannon 理論說明要完美把一個訊號以取樣,取樣率必須是被取樣訊息中最高頻率的兩倍。

CD 格式取樣率是 44.1kHz (44,100Hz) - CD 格式中最高可儲存的頻率是 22,050Hz。

96kHz 取樣率是 96kHz (96,000Hz) - 96kHz 格式中最高可儲存的頻率是 48,000Hz。

192kHz 取樣率是 192kHz (192,000Hz) - 192kHz 格式中最高可儲存的頻率是 96,000Hz。

人耳的聴覺範圍由 20Hz 至 20,000Hz。 由此可見正常來說 44.1kHz 已經大致足夠。 問題在那裡,未來再談。

數碼音樂重播專欄 (1)


今期基礎技術重溫

CD 重播中,每一秒鐘的音樂會分成 88,200 個不同的 Samples (兩聲道 x 44,100),而每一個 Sample 也儲存了 16bit 字元長度資料。 Sampling Rate 取樣率越高,每秒鐘音樂會分成 Sample 也越多,可收錄訊號最高頻率也越高。 Bit Depth 字元越長,每個 Sample 可收錄的訊號準確度越高。


筆者自我介紹

Kent Poon 潘建章於 1993 在北美開始學習錄音技術。 1997 加入世界最大音響學會 AES (Audio Engineering Society),是其中最年輕會員之一。 5 年間參與超過 600 多個錄音製作。 Kent 於早期音響雜誌撰寫數碼技術文章而為本地音響愛好者所認識。 1999 年跟加拿大 Focus Audio 合作研製 MT1 / MC1 揚聲器,供應 McGill 大學錄音部門及格蘭美得獎錄音師所採用。 由 2003 回港擔任威達公司技術顧問至 2008 年。 2000 年成為 Weiss 顧問,2010 年在香港成立 Weiss 亞洲區辦事處。 Kent 擁有一私人母帶製作所。 參與的錄音製作包括 2008 年奧運會、趙學而以及爵士原音系列。 執筆之時正聽着 Quincy Jones <From Q with Love> 精選,剛有幸發現了法國 Devalet dpremier 是當世數碼重播之頂峰。 kent@designwsound.com

數碼音樂重播專欄 (1)



review33.com
個人訊息 管理團隊
2011-04-25 01:36
[#2] Blogs: 數碼音樂重播專欄 (1)    
15 年來我都希望把錄音中最好的質數帶給音響愛好者。<<<===

最喜歡這句...support
stephen
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61.xxx.xxx.57
2011-04-26 10:47
[#3] Blogs: 數碼音樂重播專欄 (1)    
Support! Kent is nice and helpful.
com-buddy
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1.xxx.xxx.1
2011-04-26 13:15
[#4] Blogs: 數碼音樂重播專欄 (1)    
Support and looking for more in-depth comments on PC vs Mac, Firewire vs USB, FLAC vs Apple Lossless...
ff4300
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202.xxx.xxx.5
2011-04-26 13:35
[#5] Blogs: 數碼音樂重播專欄 (1)    
>>>...15 年來我都希望把錄音中最好的質數帶給音響愛好者....

"...最好的質數..." 肯定無打錯字!當中的深層意義可解作為 "....數碼音樂的最好質素...."


^______~

Vash
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219.xxx.xxx.117
2011-04-26 14:37
[#6] Blogs: 數碼音樂重播專欄 (1)    
support
skto
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203.xxx.xxx.50
2011-04-27 05:27
[#7] Blogs: 數碼音樂重播專欄 (1)    
Hi Kent,
1. I am surprised you find time to start a thread here and more so in this site instead of DWS and HiFiTrack.
2. "剛有幸發現了法國 Devalet dpremier 是當世數碼重播之頂峰" Would you please elaborate on this so that we may share your "discovery" and the virtues of the premier?
3. I am aware some audiophiles still prefer the sound of analogue LP whilst I have switched over to digital myself. I had the fortunate opportunity the other day to listen to my high resolution tracks via Avant Garde Trio driven by Kondo pre and power amps. I will be listening again next week with over a dozen direct discs played in the Kondo turntable and cartridge. I hope to be able to find out and confirm my own views on analogue LPs versus digital.
momei
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203.xxx.xxx.120
2011-04-27 06:41
[#8] Blogs: 數碼音樂重播專欄 (1)    
Thanks guys.

I always wish to collaboration with more parties. (I am doing so too).

Indeed it is quite difficult for me to write chinese articles these days, but I wish you enjoy them. These articles are published on AV Bi-weekly magazine. (This week is the first time I missed....sorry)

You will find clone of these articles on DWS and other areas too. As time goes by I wish to share with you on my audio journey, and there will be free audio samples, takes or other audio materials for download. This is what I count on web base media.

From my view, Devialet d-Premier is one of the most unique audio products for a VERY long time in hi-end market. I simply cannot find anything better in term of its feature and sound. (of course its sexy look too.) A lot of people may view it as very expansive product. I have opposite view that it's a bargain in hi-end sector. Its amplifier driving ability can compete with the best amplifiers out there, and you cannot separate its DAC and Amp ability. Devialet is not a DAC + AMP, it is merging 2 as one. I am a happy user.

I absolutely have no negative feeling of LP or analogue. Before anything is converted to digital, they are ALL analogue signal. Microphone, mic-preamp, line preamp, are all analogue circuits. LP is one analogue media, open reel is another. I have honor to listen Nat King Cole open reel safety master and Living Stereo masters, I can still remember strongly how do they sound. Capturing and transfer these materials to digital domain do not necessarily means inferior quality as well. We have very good quality A to D and D to A converters these days.

Modern production is not suffered by technologies but people who abuse it. I wish to share more in the future. Speaking of it, I am now writing this with following view. I have already worked over 30 hours, will have to get more things done before tomorrow 8am........guess I am enjoying it.

Next 2 days can share with you all Korea HiFi show. Thanks review33.com for such collaboration. Tomorrow night I will listen to Medea+ with Magico Q5, nice.


DWS
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202.xxx.xxx.254
2011-04-27 16:03
[#9] Blogs: 數碼音樂重播專欄 (1)    
.

DWS
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202.xxx.xxx.254
2011-04-27 16:20
[#10] Blogs: 數碼音樂重播專欄 (1)    
.

DWS
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202.xxx.xxx.254
2011-04-27 16:21
[#11] Blogs: 數碼音樂重播專欄 (1)    
.

DWS
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202.xxx.xxx.254
2011-04-27 16:21
[#12] Blogs: 數碼音樂重播專欄 (1)    
.

DWS
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202.xxx.xxx.254
2011-04-27 16:22
[#13] Blogs: 數碼音樂重播專欄 (1)    
.

DWS
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202.xxx.xxx.254
2011-04-27 16:23
[#14] Blogs: 數碼音樂重播專欄 (1)    
Who is she?
sugizo
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58.xxx.xxx.146
2011-04-28 00:17
[#15] Blogs: 數碼音樂重播專欄 (1)    
Bondy
ackcheng
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112.xxx.xxx.59
2011-04-28 00:47
[#16] Blogs: 數碼音樂重播專欄 (1)    
Lossless CAS platform is definitely the furture of music format but there are a very big risk.....that's how to prevent the illegal copy of such music files. The industry should have a scheme to prevent a second copy such as the SCMS (The Serial Copy Management System) as DAT adopted before.
mcc_2001
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165.xxx.xxx.150
2011-04-29 18:25
[#17] Blogs: 數碼音樂重播專欄 (1)    
The topic of illegal copying has been considered for some time by record labels in the music industry. More and more of them are offering high resolution tracks online. Why are they not as worried now as before about illegal copying? One answer is that experience has shown such infringement has not proliferated. Another answer is that copying and sending high resolution tracks around is physically prohibitive. Imagine an album of DXD produced by 2L of Norway has a file of 8 GB, about 1 GB per track, 8 tracks per album. A youngster with a PMP or iPod will decline taking it even if his friend offers it to him because his storage capacity will be overloaded. Alright a 24/96 track only has one quarter the size but is still substantial for his machines. And no one will send it around in mails even if there is capacity for the attachment because the uploading and downloading takes unduly long time. Yes, MP3 tracks are still being copied and sent around but because the price is much cheaper than CD, some prefer to buy selected tracks rather than wait for them to come somewhere.
Incorporating Digital Right Management as suggested is likely to kill high resolution sales because invariably it affects the sound. This will be a stupid move by the industry and there was already prior lesson.
momei
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203.xxx.xxx.68
2011-04-29 19:33
[#18] Blogs: 數碼音樂重播專欄 (1)    
CAS = "Computer As Source" ?! Where did you learn this? @@"

I only know CAS as "Computer Audio Source"

OMG. So surprising an "audio professional" (although only self-proclaimed) making this mistake.
sjyw
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116.xxx.xxx.224
2011-04-30 13:27
[#19] Blogs: 數碼音樂重播專欄 (1)    
Says who?

Like many acronyms, the term CAS is informally invented by people for pure convenience for the benefits of quick communication. AS far as I know, this is mostly a Hong Kong/Asia term. Countries with English as second or third language tend to make up short forms for convenience. It is not as commonly used by the American/UK audio press for instance.

For all I know, CAS could be "Computer Assisted Surgery" or thousands other representations. So to laugh as someone as being "wrong" about an informally spread term is silly. Just because someone else mentioned it before does not make it the official term.

As far as I am concerned, "Computer Audio Source" does not sound right in English anyway. To me, "Computer based Audio" sounds better; "Computer as Source" also "gels" better grammatically.

agentsmittie
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219.xxx.xxx.6
2011-04-30 14:04
[#20] Blogs: 數碼音樂重播專欄 (1)    
The term CAS.
I first learned about it in Kent Poon's web, HiFitrack and Design With Sound. It stands for computer as source.
Then I came across the term elsewhere that is supposed to mean Computer Audio System.
Then we have the web Computer Audiophile.
It is not in Wikipedia.
The "C" stands for computer, that is, using it or a varied form of it, for example, a storage system or a server to play digital tracks.
momei
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218.xxx.xxx.88
2011-04-30 14:44
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