How does TuneBrowser handle CD (.wav) files with 'Pre-Emphasis'?

フォーラム TuneBrowser How does TuneBrowser handle CD (.wav) files with 'Pre-Emphasis'?

このトピックには13件の返信が含まれ、2人の参加者がいます。5 ヶ月、 2 週間前 Tiki さんが最後の更新を行いました。

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  • #5021

    Andrew ACTON
    参加者

    Greetings Tiki

    I have a question about how TuneBrowser plays back ‘ripped’ Compact Discs (.wav format) with  ‘Pre-emphasis’.

    Questions:

    (1) Does TuneBrowser detect CD (.wav) files that contain pre-emphasis?

    (2) If TuneBrowser can detect pre-emphasis, does it automatically apply (digital) de-emphasis?

    (3) If TuneBrowser can manage (.wav) files with ‘pre-emphasis’ could a new indicator “EMPH” be added (like those for “Tune Samplerate” “Device SampleRate”. It would be very useful to see some dynamic indication in TuneBrowser … regarding pre-emphasis processing.

     

    From my reading, Compact discs ‘ripped’ to a computer (.wav) WILL INCLUDE the 2 pieces of data to tell the playback device (CD player or software program) to apply de-emphasis for a CD that was mastered with Pre-emphasis:

    (1) A setting in the CD TOC.
    (2) CD Subcode data in each track.

    Background:

    In the early years of the Compact Disc, some CDs were encoded with ‘Pre-emphasis’ (particularly those from Japan). When a conventional CD player detected a CD with ‘Pre-emphasis’ the signal was de-emphasised with analogue circuits in the CD player to restore the correct frequency response.

    Some HI-Fi CD players (I personally had one) also indicated “Emphasis” in their graphical display to indicate the playback of a disc with “Pre-emphasis”.

    Perhaps TuneBrowser can be one of the few programs to correctly handle audio (.wav) files, which were encoded with ‘pre-emphasis’  🙂

    With thanks (as always),

    Andrew Acton

     

    Ref: https://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio

    “Pre-emphasis”
    Some CDs are mastered with pre-emphasis, an artificial boost of high audio frequencies. The pre-emphasis improves the apparent signal-to-noise ratio by making better use of the channel’s dynamic range. On playback, the player applies a de-emphasis filter to restore the frequency response curve to an overall flat one. Pre-emphasis time constants are 50µs and 15µs (9.49 dB boost at 20 kHz), and a binary flag in the disc subcode instructs the player to apply de-emphasis filtering if appropriate. Playback of such discs in a computer or ‘ripping’ to wave files typically does not take into account the pre-emphasis, so such files play back with a distorted frequency response.[citation needed]”

    #5023

    Tiki
    キーマスター

    Hi,

    Thank you for your detailed explanation.

    About one year ago, it was talked about pre-emphasis in this forum.

    https://tunebrowser.tikisoft.net/forums/topic/799/ (In Japanese)

    Unfortunately, TuneBrowser is not support pre-emphasis (de-emphasis). I have no resource to do de-emphasis. I’m sorry, but I could not meet your expectation at this time.

    Thanks.

    #5026

    Andrew ACTON
    参加者

    Hi Tiki

    Thank you for your quick reply.

    It is my mistake because I searched the forum in English for “pre-emphasis” and did not find your original answer.  I should have used Japanese language search and locate the old answer regarding “プリエンファシス” !

    Since I can only read my (native) English… normally I use Google translate to read the (mostly) Japanese forum.  🙂

    Many thanks,

    Andrew Acton

    #5027

    Tiki
    キーマスター

    Hi, Andrew

    I know it is not easy to search old topics. Especially by differnet languages. So, off course, it’s not your mistake. Please do not mind.

    And now, I’m going to restart studying Pre-emphasis (and also HDCD). These are old technologies in this Hi-Res days, but I understand that it can not be ignored.(^^)

    Thanks.

    #5396

    Tiki
    キーマスター

    Hi Andrew,

    I have released 4.9.0 preliminary version. This version is now supporting pre-emphasis and HDCD decoding by default.

    These decodings are applied on playback or CD ripping.

    If pre-emphasis flag found in CD track info and de-emphasis was applied in CD ripping, bit width will be expanded into 24bit and stored into file (Wav/FLAC and so on). So playback can process as normal 24bit file.

    Sorry, but above is easy explanation. Please check change log by translation (^^;. And if you have pre-emphasis-ed CD, please try, and if you have any questions or opinions, please talk here again.

    Thanks!

    #5406

    Andrew ACTON
    参加者

    Greetings Tiki,

    This is great news, thank you again.

    I have several CDs that use pre-emphasis … I will check those in TuneBrowser in the coming weeks (currently away from home).

    In addition I have a copy of this Pierre Verany CD “Digital Test” Ref:

    https://www.stereophile.com/content/recording-november-1988-ipierre-verany-digital-test-cdi

    This CD is rather special because it is a very rare example where the same recording (track) has been INTENTIONALLY  recorded in the sub-code emphasis bit and off on the same music.  This is extremely useful for testing if the ripping process and playback pocess correctly manages the pre-emphasis bit.

    Ref:

    37. Analogue Desemphasis Circuit Audible Incidence: Music Recorded With Pre-Emphasis On – Slovak Philharmonic Orchestra/Kurt Redel

    38. Analogue Desemphasis Circuit Audible Incidence: Music Recorded With Pre-Emphasis Off – Slovak Philharmonic Orchestra/Kurt Redel

    If you ‘rip’ these tracks and look at the spectrograph of the waveform obviously different.  In addition if you listen to each track its very easy to hear the difference when the pre-emphasis is not handled correctly.

    I will use these 2 tracks to test TuneBrowser.

     

    Please give me a few weeks to respond with the results.

    Regards,

    Andrew Acton

     

     

    #5413

    Tiki
    キーマスター

    Hi Andrew

    Thank you for your response and details even though you are busy.

    Please give me a few weeks to respond with the results.

    Okay, please don’t push yourself. I’ll wait. (^^)

    Thanks.

    #5560

    Andrew ACTON
    参加者

    Greetings Tiki

    I would like to give you some feedback regarding the new Pre-emphasis support in TuneBrowser V4.9.0.

    I can report everything works correctly! 🙂

     

    I tested the function with .WAV files extracted from the original CD.

    The CD I used has specific tracks to test pre-emphasis ON (Track 37) and OFF (Track 38) for identical music.

     

    Reference CD:

    CD Title: “Digital Test – Digital Tests & Demonstration Tracks”

    Publisher: “Pierre Verany”

    Cat No: “PV.788031/788032”

     

    Specifically:

    Track 37: “Analogue De-emphasis Circuit Audible Incidence, Music recorded with pre-emphasis ON”

    Track 38: “Analogue De-emphasis Circuit Audible Incidence, Music recorded with pre-emphasis OFF”

     

    Using these two tracks, the resulting sound should be the SAME if the pre-emphasis and de-emphasis circuits/processing are  working correctly (CD player or PC Software).

    Since I only use .WAV files extracted from the original CD, I used the TuneBrowser (manual) tagging method to set the pre-emphasis flag to ‘1’ for tracks requiring de-emphasis.

    Before TuneBrowser V4.9.0 (no pre-emphasis support) if you listen to ‘Track 37’ (it HAS pre-emphasis ON when mastered)… the sound is far too ‘bright’ with an over emphasis of higher frequencies (incorrect).

    After I setup TuneBrowser V4.9.0 for pre-emphasis processing and set the pre-emphasis flag to ‘1’ for this track, track 37 and 38 now sound identical (correct).

    So THANK YOU VERY MUCH for yet another great improvement to TuneBrowser.

    🙂

    Cheers,

    Andrew

     

    P.S I add my setup notes below for other TuneBrowser Users (English):

    —————————————————————————————————
    —————————————————————————————————
    Enabling Tunebrowser (V4.9.0 and higher) Pre-Emphasis Support

    One-time Setup:
    ————–
    (a) Go to: File / Preferences / Tags / Title & Tag
    – Use the ADD button.
    – ADD NEW ITEM ‘Pre-emphasis’ (under the Property Column… ‘Pre-emphasis’ will now be shown).
    – For the ‘Pre-emphasis’ entry you just created add ‘PRE_EMPHASIS’ as the Value.

    (b) Go to: File / Preferences / Playback Settings / Decoding / Decoding misc / Automatic De-emphasis
    – Choose ‘Yes’ to enable pre-emphasis checking/processing.

    Ongoing Setup:
    ————-
    (a) For each track (or complete CD) that was encoded with pre-emphasis, set the ‘Pre-emphasis’ value to ‘1’ under the ‘Properties Panel’ (for the track or entire CD).
    Note: Select the track(s) / CD and use the Right Mouse Button to access the ‘Properties Panel’.

    When TuneBrowser plays back a track (in my case .WAV file) with the pre-emphasis flag set to ”1’… TuneBrowser uses DSP (44.1 kHz 24 bit) to apply the correct de-emphasis.

    —————————————————————————————————
    —————————————————————————————————

    #5561

    Tiki
    キーマスター

    Hi Andrew,

    Thank you very much for your confirmation and setup notes (nice !). I’m very very glad to know your confirmation results. Honestly, I was pretty relieved (^^;.

    As talking in another topic, to detect pre-emphasis flag of CD media, current TuneBrowser is reading TOC only. But some CDs are containing it in subcode area of sector frame, instead of TOC. So, I’m now trying to read subcode area to increase certainty of pre-emphasis flag detection.

    Please watch the topic, if your interest is continuing.

    Thanks again,
    Tiki

    #5562

    Andrew ACTON
    参加者

    Hi Tiki

    Reading the Q Channel to check the pre-emphasis bit would seem to be the ultimate solution!  From what I read that data is preserved in a ripped (.wav) music file.   That means TuneBrowser could dynamically check (at playback time) and completely eliminate any manually tagging for pre-emphasis.

    I will certainly monitor the forum and the discussion for your news 🙂

    In the meantime, the pre-emphasis solution in V4.9.0 is greatly appreciated and works!

     

    Also:

     

    (a) I assume you have seen the official Philips/Sony ‘Red Book’ Ref: ‘Compact Disc Digital Audio System Description Version March 2006’?

    On p.41 the data format of the Q Channel is described in great detail (including all possible pre-emphasis values), data structure etc.

     

    (b) I downloaded the program “CD Manipulator” last published in 2004! It seems to be able to perform deep analysis of the ‘sub channel’ data… perhaps that will provide clues to reading the Q Channel from a CD or WAV file?  Interestingly the source code is freely available from the author’s website.

     

    (c) If you have time, can you consider adding a small indicator (like the existing ones for “SHAR” “EVNT” “BITP” “MONO” “WAIT” etc.) to illuminate and say “EMPH” when TuneBrowser has activated playback de-emphasis for a track?

     

    Pleased you liked my instructions.  🙂

    Cheers, Andrew

    #5567

    Tiki
    キーマスター

    Hi Andrew,

    Thank you for your suggestions (^^).

    (a) Red Book

    I know the existence of Red Book, but I have not seen the real thing.

    But good informations from great pioneers are existing in Internet.

    For example;

    http://www.amy.hi-ho.ne.jp/tachibana/toi/cd/cd.htm
    http://senbee.seesaa.net/article/21692955.html
    (All pages are written by Japanese)

    (b) CD Manipulator

    I already checked the source code of the CD Manipulator. Thanks.

    License model of this software is not matched for the TuneBrowser, so I cannot reuse published source code. But these are very helpful for my study.

    (c) Indicator
    Simple “EMPH” indicator is already implmented. Isn’t it showing while realtime de-emphasis is applying on playback ?

     

    Thanks again

    Tiki

    #5569

    Andrew ACTON
    参加者

    Hello Tiki,

    – We are all grateful to those pioneers 🙂

    – I have seen the “Red Book” and it can be obtained from the publisher via an official process.  The process to get a copy (a PDF) is a little complex, however if you are interested please email me directly for the instructions.  The pre-emphasis explanation in the “Red Book” is similar to your links, however its always useful to have the original information from the designers.

    – Thank you for the links to additional information 🙂

    – I was so busy LISTENING to the pre-emphasis vs no-emphasis music playback I did not see the “EMPH” indicator!   I use the Google translated ‘Change Log’ and I did not see “EMPH” indicator mentioned as a new feature.   Anyway I see the “EMPH” indicator light up NOW (for tracks with pre-emphasis processing) and disappear for tracks with no pre-emphasis.  See attached screen copy.    PERFECT!

    – Thank you again… perhaps we can close this thread?

    Thanks again,

    Andrew

    #5570

    Andrew ACTON
    参加者

    Screenshot

    Attachments:
    #5573

    Tiki
    キーマスター

    Thank you, Andrew.

    Currently, Q SubCode information may be enough (My hot issue is, how to read sectors and frames via Win32 API. This requires testing and adjusting). When I need your help in future, I’ll contact you.

    perhaps we can close this thread?

    Yes. Thank you again !

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