Quite so, Tom - I think the original drift of this thread was about getting 
the audio off in higher quality than using a conventional DAT machine by 
eliminating interpolation. If such large errors as usually require 
interpolation cause trouble, then some poor devil with a CEDAR will have to 
fix them if the audio is to be used, and in many instances this would, of 
course, be counter-productive. But for an obsessionally accurate transfer of 
the data which is actually in the file, the method may have its uses...



----- Original Message ----- 
From: "Tom Fine" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, January 21, 2010 11:41 AM
Subject: Re: [ARSCLIST] DAT ripping


> Ted, I understand the point of knowing about an error. But, does the 
> tape-drive-to-computer method CORRECT the error for the purpose of USING 
> the audio? That's the whole point of error-correction in the DAT machine 
> design (and in CD players) -- to make the audio stream usable to the 
> average listener. What is the point of transfer if the audio can't be 
> used? So far no one has confirmed that the direct-to-computer method 
> provides as good error correction abilities as just playing the DAT.
>
> As to Shai's point about multiple passes -- I too have had success once in 
> a while re-playing what had been a dropout. It doesn't work all the time, 
> but often enough that I'll do it with problem tapes. And yes, problem 
> tapes can have the "error" indicator light flashing constantly or on for 
> long periods of time yet recovered music stream flowing out.
>
> One other point -- you have the same mechanical issues with a computer 
> drive as a DAT machine, no? It's the same method of a rotary head 
> recovering data from a magnetic tape, isn't it?
>
> -- Tom Fine
>
> ----- Original Message ----- 
> From: "Ted Kendall" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, January 21, 2010 6:11 AM
> Subject: Re: [ARSCLIST] DAT ripping
>
>
>> Well, if an error is corrected, you won't know about it from looking at 
>> the file. If it isn't, and there is no interpolation, it will show up as 
>> corrupt data. Agreed that multiple passes can affect error rate one way 
>> or the other, especially with that ultra-thin tape they use.
>>
>>
>>
>> ----- Original Message ----- 
>> From: "Shai Drori" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Thursday, January 21, 2010 9:14 AM
>> Subject: Re: [ARSCLIST] DAT ripping
>>
>>
>>> Okay, that I understand, but I am thinking about correctable errors. We 
>>> are then assuming that both systems will correct the errors the same way 
>>> since both use the schemes implemented. How do we know which system has 
>>> fewer errors over the other? My experience with rotary head systems is 
>>> that sometimes second or third reading yielded better results, I think 
>>> due to "cleaning" actions of the previous playing. Maybe we should 
>>> compare five readings of the same cassette?
>>> Shai
>>>
>>> Ted Kendall wrote:
>>>> In my view, yes.
>>>>
>>>> Consider - you have two data files. One is a text document (for the 
>>>> sake of argument). The other is a digital audio file. Both have errors 
>>>> in the storage medium. This is inevitable, so we devise error 
>>>> correction strategies (redundancy, check codes, etc). These allow us to 
>>>> correct errors completely and accurately.
>>>>
>>>> Suppose now that there is an error in the storage medium which is too 
>>>> large to be corrected. This will cause an obvious error in the text 
>>>> file, which is unaceptable, so the system does not allow for it and 
>>>> declares the file corrupt. The audio file, however, can be rendered 
>>>> inoffensive by interpolation, and this is implemented in the DAT audio 
>>>> format. If we retrieve DAT audio in a system which does not admit of 
>>>> interpolation, we therefore know that the data are accurate, as any 
>>>> uncorrectable errors are recorded as such.
>>>>
>>>>
>>>>
>>>> ----- Original Message ----- From: "Shai Drori" 
>>>> <[log in to unmask]>
>>>> To: <[log in to unmask]>
>>>> Sent: Thursday, January 21, 2010 7:37 AM
>>>> Subject: Re: [ARSCLIST] DAT ripping
>>>>
>>>>
>>>>> My own experience with dat is that almost all tapes have some form of 
>>>>> errors on them. I think the idea in dds is that errors are better 
>>>>> fixed than dat machines. There were many machines that came off 
>>>>> assembly lines not at spec, thus making the tape not a standard tape. 
>>>>> Some machines are better at coping with these (my experience with Sony 
>>>>> is better than tascam for example, but I suspect this is highly 
>>>>> subjective). All in all, I think the DAT format was the word digital 
>>>>> format I have ever come across.
>>>>> Also' checking two files one against the other will not necessarily 
>>>>> prove one format better than the other. If you get some audio, how can 
>>>>> you be sure one stream is correct and the other is corrupt? Either the 
>>>>> dat or dds stream could be better, or am I missing something in the 
>>>>> methodology?
>>>>> Shai
>>>>>
>>>>> Tom Fine wrote:
>>>>>> I'm happy to do a SPDIF to hard drive transfer and then exchange 
>>>>>> tapes with someone using a PC-drive transfer system so we can do the 
>>>>>> comparison Richard mentions.
>>>>>>
>>>>>> Please ping me off-list if you have a working PC-drive transfer chain 
>>>>>> and want to exchange DATs and computer files.
>>>>>>
>>>>>> -- Tom Fine
>>>>>>
>>>>>> ----- Original Message ----- From: "Richard L. Hess" 
>>>>>> <[log in to unmask]>
>>>>>> To: <[log in to unmask]>
>>>>>> Sent: Wednesday, January 20, 2010 5:14 PM
>>>>>> Subject: Re: [ARSCLIST] DAT ripping
>>>>>>
>>>>>>
>>>>>>> Hi, Tom,
>>>>>>>
>>>>>>> After I saw your post and re-read Jim's post, I think I understand 
>>>>>>> where he is coming from.
>>>>>>>
>>>>>>> What we _should_ be able to do is take the DDS ripped file and an 
>>>>>>> AES/SPDIF'd copy of the DAT from an audio DAT machine, align the 
>>>>>>> starts, invert the phase of one, and get dither or silence.
>>>>>>>
>>>>>>> In both instances, we're pulling numbers off the tapes (although the 
>>>>>>> basest representation of the numbers is analog on the tape, the 
>>>>>>> processing in both instances interprets these analog signals as 
>>>>>>> either ones or zeros).
>>>>>>>
>>>>>>> I would not, without doing the tests that Jim is talking about, be 
>>>>>>> 100.0000% confident that the two files are identical.
>>>>>>>
>>>>>>> I think that the DDS reading could be "better" than the audio DAT 
>>>>>>> reading as there is no error concealment stage in a data recorder, 
>>>>>>> so if you grabbed all the bits via the DDS route, you could be sure 
>>>>>>> that they were correct.
>>>>>>>
>>>>>>> These are all subtle differences and are probably not as large as 
>>>>>>> the "Interstitial Errors" that Chris Lacinak is talking about here:
>>>>>>> http://www.avpreserve.com/wp-content/uploads/2010/01/Digital_Audio_Interstitial_Errors.pdf
>>>>>>>
>>>>>>> I would expect some burst differences between the two methods, and 
>>>>>>> those bursts would be where the audio DAT's error concealment kicked 
>>>>>>> in. Other than that, they should be identical, presuming you haven't 
>>>>>>> introduced an interstitial error in one copy or the other.
>>>>>>>
>>>>>>> I'm glad to see Chris offering to help. I am interested in this. I 
>>>>>>> would also like to know who is set up with the DDS Mass Ingest of 
>>>>>>> DATs as I am sometimes asked who can do large DAT collections. At 
>>>>>>> the moment, I am not interested in doing any because of anticipated 
>>>>>>> remaining headlife on my machines, the growing lack of parts for DAT 
>>>>>>> machines, the need to transfer my own DAT collection first, and the 
>>>>>>> analog work that I have piling up.
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> Richard
>>>>>>>
>>>>>>> At 04:27 PM 2010-01-20, Tom Fine wrote:
>>>>>>>> Hi Jim:
>>>>>>>>
>>>>>>>> How could the data be "better" than a direct-digital out from a 
>>>>>>>> properly-working player (ie no head problems or mechanical issues)? 
>>>>>>>> I thought the main advantage of the computer-drive method was to 
>>>>>>>> save time. Is there more to it?
>>>>>>>>
>>>>>>>> -- Tom Fine
>>>>>>>>
>>>>>>>> ----- Original Message ----- From: "Jim Sam" <[log in to unmask]>
>>>>>>>> To: <[log in to unmask]>
>>>>>>>> Sent: Wednesday, January 20, 2010 12:45 PM
>>>>>>>> Subject: Re: [ARSCLIST] DAT ripping
>>>>>>>>
>>>>>>>>
>>>>>>>>> All,
>>>>>>>>>
>>>>>>>>> First, Dave, that information is very helpful.
>>>>>>>>>
>>>>>>>>> That said, I didn't ask because I'm worried about the theory.  I 
>>>>>>>>> was asking
>>>>>>>>> for a collaborator in testing.
>>>>>>>>>
>>>>>>>>> The theory's been discussed before on this list, and I'm aware 
>>>>>>>>> that more
>>>>>>>>> than one person/organization has experimented with this to some 
>>>>>>>>> success.  It
>>>>>>>>> was also *briefly *discussed at last year's conference in DC. 
>>>>>>>>> However,
>>>>>>>>> every time I've seen a discussion about the topic, it has never 
>>>>>>>>> come along
>>>>>>>>> with what matters to me: testing to make sure what's coming off 
>>>>>>>>> the DDS
>>>>>>>>> drive is the same (or better) data than what would go down the 
>>>>>>>>> AES/EBU
>>>>>>>>> pipeline.
>>>>>>>>>
>>>>>>>>> I'm still extremely interested in this situation, and after having 
>>>>>>>>> had to
>>>>>>>>> deal with other similar formats, I've got ideas for testing that 
>>>>>>>>> I'd like to
>>>>>>>>> do.  But I don't have a working DDS setup here.  I could build my 
>>>>>>>>> own, which
>>>>>>>>> I might do, but that's a can of worms, and there's other things to 
>>>>>>>>> be gained
>>>>>>>>> by having a collaborator in these tests.
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Jim
>>>>>>>>
>>>>>>>> Richard L. Hess                   email: [log in to unmask]
>>>>>>>> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
>>>>>>>> Detailed contact information: 
>>>>>>>> http://www.richardhess.com/tape/contact.htm
>>>>>>>> Quality tape transfers -- even from hard-to-play tapes.
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>