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Author Topic: Jitter?  (Read 3123 times)

Xena

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Jitter?
« on: November 25, 2008, 01:19:28 pm »

I am hoping to find my ultimate program for ripping my CDs, and Media Jukebox may be the one. However, unlike CDex and Cowon Media Center, I cannot find an option for Jitter correction. I'm ripping CDs to FLAC for play on a Cowon D2.

Is there currently ... or planned ... an option for Jitter correction?

Thanks for any insight you can provide.
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Matt

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Re: Jitter?
« Reply #1 on: November 25, 2008, 01:42:54 pm »

Media Center (and Media Jukebox) has very good secure ripping:
Options > CD & DVD > Advanced Ripping Options... > Copy Mode: Secure

Jitter is not relevant if you use secure ripping.  You'll get a secure report at the end of the rip and can sleep sound at night if it tells you the rip was good.
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Matt Ashland, JRiver Media Center

Alex B

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Re: Jitter?
« Reply #2 on: November 25, 2008, 01:50:46 pm »

"Jitter correction" is nonsense. I don't know what it is supposed to do, but certainly it does not help if you are trying to rip a scratched CD.

I'd recommend enabling the secure ripping mode and rip logging.

You can find more info here: http://yabb.jriver.com/interact/index.php?topic=29157.0  (The program in the screenshot is MC11. MJ12 may look a bit different, but the actual settings should be similar)


(...and what Matt said. He replied while I was searching the link.)
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Xena

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Re: Jitter?
« Reply #3 on: November 25, 2008, 02:43:20 pm »

Alex, I don't have any scratched CDs. But I do have a desire to have the highest quality of rips I can get. I'm not sure I understand how "secure" ripping corrects time/phase errors. Perhaps the slightest explanation would help me. I'm no expert, but I'm not sure Secure ripping does anything other than a bit-by-bit verification. Again, not sure this fixes the issue.

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

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Re: Jitter?
« Reply #4 on: November 26, 2008, 03:23:41 am »

I am sorry, but I don't have any more detailed information about "audio CD jitter". I can only say that it has not been an issue here or at www.hydrogenaudio.org which is another forum I regularly visit.

The wiki article in your link may be partially misleading. It may give the impression that "audio CD jitter" somehow affects the overall long term audible quality of the ripped PCM data. In my experience there can't be such a phenomenon with modern hardware when audio data is extracted in the original digital form. The audio quality is either exactly perfect, i.e. unaltered, or the ripped data may contain occasional errors because of read errors. In addition, the article doesn't mention the difference between the so called "burst mode" and "secure mode" rippers at all.

The secure mode in JRiver programs works quite similarly like the secure mode in Exact Audio Copy, which is a well-known dedicated ripper program.

The Secure mode is not intended only for visibly scratched CDs. An audio CD can have more or less damaged sectors that produce clicks or other audible artifacts even though the disc surface looks fine. The secure mode always tries to read the sectors twice. If a certain sector does not produce bit identical results the program does several reread attempts in order to get a reliable result. All reread attempts and their results are logged so that you can check the possible problem passages later. Sometimes even a failed sector does not produce any audible problems.

EDIT

I did some searching and it seems that "jitter correction" is something that is possibly usable with very old drives that don't have the so called "accurate stream" feature. However, I wasn't able to find any detailed technical explanation about "jitter correction".

All modern drives are said to have "accurate stream" and if I have understood correctly the secure mode needs this feature in order to work. Otherwise it could not revisit a given sector because the drive would most likely go to a slightly different sector. The log would be full of errors and the rip would fail.


Perhaps JohnT from JRiver could explain this better. I think he is the developer who designed JRiver's secure ripping system.
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Xena

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Re: Jitter?
« Reply #5 on: November 26, 2008, 10:01:11 am »

Thank you for that additional post Alex. That helps me understand a bit better. I do know jitter is something that received a lot of attention several years ago among the "audiophile" group (of which I'm not really a member, but I keep my finger on the pulse of hi fi goings on). It could well be that modern CD players obviate the need for "jitter correction" and the feature is added to some ripping software for legacy purposes.

I'd be interested in hearing if this is true from one of the developers of the software.
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marko

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Re: Jitter?
« Reply #6 on: November 26, 2008, 02:40:42 pm »

Jitter - Schmitter...

What I want to know is...

Are you the Warrior Princess?

:D

Xena

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Re: Jitter?
« Reply #7 on: November 26, 2008, 05:23:25 pm »

Of course ... sorry ... I've fixed that oversight ...


Jitter - Schmitter...

What I want to know is...

Are you the Warrior Princess?

:D

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Alex B

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Re: Jitter?
« Reply #8 on: November 27, 2008, 02:36:34 am »

I do know jitter is something that received a lot of attention several years ago among the "audiophile" group (of which I'm not really a member, but I keep my finger on the pulse of hi fi goings on).

I think that attention was given to a different kind of jitter. They were speaking about digital jitter that may occur during playback when digital signal is transferred between digital devices, usually from the player device to the DA circuit, which converts it to analog. AFAIK, this kind of jitter can be caused by inaccurate or uncynced clock circuits. I have read about it, but I have never been able to detect it on my playback systems.

Anyway, I don't think it has anything to do with CD ripping. During CD ripping the bits are transferred as they are. There are no clock circuits involved.
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