audio to .tzx conversion: a "lost bit" issue?

From	Ivan Shmakov <oneingray@gmail.com>
Newsgroups	comp.sys.sinclair
Subject	audio to .tzx conversion: a "lost bit" issue?
Date	2013-01-17 19:36 +0000
Organization	Aioe.org NNTP Server
Message-ID	<87k3rbbo08.fsf@violet.siamics.net> (permalink)

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	FWIW, I've got some rather old (as in: early 90'ies) ZX Spectrum
	tapes, and now trying to read them into .tzx files.  After
	digitizing one of the tapes and running over some SoX [1] tweaks
	(to apply some gain, and select just one of the channels), I've
	finally got audio2tape(1) (as bundled with the FUSE emulator
	[2]) to recognize the data... almost: it seems to lose one bit
	to one byte of data in the process.  Consider, e. g.:

Block ended, found 18 bytes
Type: Data
Error have incomplete byte (7 bits)
First block seconds: 19.6456
Last block seconds: 24.5804
Checksum:FAIL

	This block looks like a standard 19-bytes Spectrum header
	(presumably for a BASIC program, as this is the first block on
	the side), but only with the last bit lost.

Block ended, found 260 bytes
Type: Data
Error have incomplete byte (3 bits)
First block seconds: 25.5527
Last block seconds: 28.7592
Checksum:FAIL

Block ended, found 47 bytes
Type: Data
First block seconds: 28.7607
Last block seconds: 29.0521
Checksum:FAIL

Block ended, found 18 bytes
Type: Data
Error have incomplete byte (7 bits)
First block seconds: 33.9866
Last block seconds: 38.9156
Checksum:FAIL

	This block looks like one more header (sans the trailing bit)...

Block ended, found 6911 bytes
Type: Data
Error have incomplete byte (6 bits)
First block seconds: 39.8885
Last block seconds: 76.5504
Checksum:FAIL

	... And this one looks (and, well, sounds) just like a SCREEN$
	file data, yet again -- with a couple bits lost (of the usual
	6912 bytes.)

	Any idea what may be happening there, or what else could I try?

	TIA.

[1] http://sox.sourceforge.net/
[2] http://fuse-emulator.sourceforge.net/

-- 
FSF associate member #7257

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Thread

audio to .tzx conversion: a "lost bit" issue? Ivan Shmakov <oneingray@gmail.com> - 2013-01-17 19:36 +0000
  Re: audio to .tzx conversion: a "lost bit" issue? "Brian Gaff" <Briang1@blueyonder.co.uk> - 2013-01-18 09:14 +0000
    Re: audio to .tzx conversion: a "lost bit" issue? Ivan Shmakov <oneingray@gmail.com> - 2013-01-18 19:41 +0000
      Re: audio to .tzx conversion: a "lost bit" issue? "Daniel Mandic" <daniel_mandic@hotmail.com> - 2013-01-18 20:13 +0000
  Re: audio to .tzx conversion: a "lost bit" issue? Fred <fredm@spamcop.net> - 2013-01-18 06:53 -0600
    Re: audio to .tzx conversion: a "lost bit" issue? Ivan Shmakov <oneingray@gmail.com> - 2013-01-21 08:59 +0000
      Re: audio to .tzx conversion: a "lost bit" issue? Fred <fredm@spamcop.net> - 2013-01-22 14:52 -0600

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