其實點解唔同 BDP 出來既聲會有明顯分別？

NETDSL0100

我地要大膽假設,小心求證

tinghai

首先要清楚HDMI support 唔同既Audio protocol 如 LPCM, DTS HD∕Dolby TrueHD bit stream 同 DTS∕Dolby Digital bit stream, 所以就算用HDMI去接個BDP到AV Receiver 其實唔一定Receiver收既係 DTS HD∕Dolby TrueHD bit stream. 道理就好似ethernet上可以行行唔同protocol. 問題係BD還有Bonus View同Secondary audio,好似Oppo 83為例,如著咗Secondary audio就算你HDMI output setting係bit stream而隻碟有DTS HD∕Dolby TrueHD audio咁佢只會downgrade落輸出DTS∕Dolby Digital bit stream而無咗DTS HD∕Dolby TrueHD bit stream.

解答29樓的問題:
1 所有有Dolby TrueHD 既Blu Ray必須提供separate AC-3 audiotrack, 而且個decoder可以downmix Dolby TrueHD or DTS HD 去2 channel 或5.1 channel. 所以唔係Dolby TrueHD包DD而根本有條separate AC-3 Track 係碟度
DD (lossy format 5.1-channel 16-bit/48 kHz at 640 kbit/s) vs
Dolby TrueHD (lossless format, 24 bit audio in up to 8 discrete audio channels at 96 kHz or up to 6 channels (5.1 surround) at 192 kHz.The max bit rate 18 Mbit/s)

即多D 數位同高sampling rate, 有師兄話聽到不同BDP有分別其實差D個條聲其實只係bit stream緊DTS/DD而不是Dolby TrueHD/DTS HD

2. DRC (Dynamic Range Control)係Dolby TrueHD decoding個時做,係BDP bit stream transmission to Receiver 之後發生

3. 唔係好明,可能係個別牌子setting其實係強迫架player bit stream DTS∕DD

4. 其實無論係DTS HD∕Dolby TrueHD 係隻碟係一個壓縮咗既file,bit stream係個BDP 一邊讀一邊stream D 數據直接去HDMI output,中間不經 player 既decoder,大家是否唸多咗呢?

最實際係個Receiver 有冇點DTS HD∕Dolby TrueHD燈,你就肯定夠竟BDP係咪bit stream緊DTS HD∕Dolby TrueHD去Receiver

To #30

Any interference or error introduced to the bit stream will cause error to the digital data itself, like a corrupted file, and will not change the analog aspect of the content e.g. sound volume, additional sound, EQ etc. This is the main misconception when we are dealing with digital content when compare with analog domain. The original brother asked whether there are differences between BDP player if bit-stream is used to output the audio content to the AV Receiver. The answer is absolutely no difference. For brothers who claim to hear the difference could is likely caused by mis-configuration of the player settings. e.g. I just tried to turn on Secondary Audio option "On" on an Oppo-83 and immediately the AV Receiver display changed from Dolby TrueHD bit-stream to DTS bit-stream only on my Spiderman Blu-Ray disc. Of course this will make a huge difference.

Technology is bound by scientific facts and law of physics. Unfortunately in the HiFi/AV business, vendors tends to ignore the scientific facts (who cares anyway) and try to create myths in order to differentiate their products and make $$$.

Raphael

在pdf內, 有項"MLP BITSTREAM FORMATS"
問題出現在這裡,

問題
1) example : Dolby True HD 是包含 Dolby ...
bbsai 發表於 2012-1-3 15:56

向師兄請教一下, 所謂 DRC 係乜?

bbsai

向師兄請教一下, 所謂 DRC 係乜?
Raphael 發表於 2012-1-3 22:02

其他品牌我未必知, 但AV amp.有這項選擇的, 但player都會有, 我之前用sony 350/370 BD Player 有DRC的, 並非上面位ching在AV amp後, 還有350/370係一定要AV amp去解 bitstream 的 player, 但這個設定確實在player出現的!

DRC 係一個影響sound effect的設定, 全取時聲音會最動態, 在bitstream未解碼都可以設定的!

Overnite

回復 32# tinghai

Once it is admitted that there will be errors in "realtime transmission" of digital av signals, we should also question the ability of a player to 100% faithfully extract the bitstream from the disc. Errors can be introduced by the non-uniform speed of the drive, poor PCB design and internal wirings leading to interference.

Once there are bit errors, the reproduced analogue waveforms in the receiver will have distortion and are discernible.

Many of the gadgets in AV field like power cables, fuses and signal cables do bring positive changes to the system, but they are really overpriced. Whether it is worth is very personal. It is like those expensive handbags which are loved by many ladies.

When it comes to entertainment and enjoyment, price has no limit.

tinghai

其他品牌我未必知, 但AV amp.有這項選擇的, 但player都會有, 我之前用sony 350/370 BD Player 有DRC的,  ...
bbsai 發表於 2012-1-3 22:39

Yes DRC can happen in the player but not when you bit-stream to the Receiver. DRC on the player is only valid when you decode the Audio in using the player's decoder because DRC is part of Dolby TrueHD feature, which means your HDMI audio output will be LPCM and not bit-stream. Setting the DRC "On" on the player does not mean the bit-stream will be applied with DRC. Since the original brother asked whether there are difference when the output is bit-stream, in this case I stated that DRC will happen in the Receiver. If the audio is decoded in the player the HDMI audio output signal will be LPCM.
   
On the Player:

DRC On, HDMI output LPCM = Dolby TrueHD Decoding in Player with DRC processing applied
DRC On, HDMI output bit-stream, Dolby TrueHD = No decoding in player therfore no DRC process in output Dolby TrueHDbit-stream
DRC On, HDMI output bit-stream, Secondary Audio On/Bonus View On = Some player will downgrade to DTS/DD bit-stream, since DRC only applies on Dolby TrueHD, no DRC processing in bit-stream

Hope this information helps

bbsai

首先要清楚HDMI support 唔同既Audio protocol 如 LPCM, DTS HD∕Dolby TrueHD bit stream 同 DTS∕Dolby D ...
tinghai 發表於 2012-1-3 21:59

老實講ching, 你的執著我是理解的, 但你發覺出來的結果和自己學的一套不太match, 會否尋求可以理解當中原理?
最基本我有做求証, 用得出來的結果, 想一想自己是否學不足夠?!


我提過問題 3 & 4, 難道你未試過有分別?? sleep mode on/off & dolby true HD / Direct "dolby true HD" 分別 ?

Overnite

雖然我都覺得有些影音配件及器材是有水分的存在，但不可否認影音工程學是一門很專門的學科。可能一個電子工程師要進入影音產品設計的行業，也要重新學習這方面的知識。

如果在享受影音樂趣之餘，能對當中的知識和理論多理解，也可以是另一種樂趣。

chhanthony

http://en.wikipedia.org/wiki/Jitter

Overnite

Thanks Ching for the info, with an example of audio cd which may not be able to read error free digital audio data from a disc.