DV Playback in DVCPro Deck at DVinfo.net

Alfred Wirtenberg · September 28th, 2006, 07:40 PM

I use a Panasonic AJ-D250 deck (DVCPro) to play back full-size DV tapes (Panasonic AMQ's, which can be up to 276 minutes long). Everything works fine, except that during rewind and fast forward I can't prevent the deck from feeding out a high speed version of the video (somewhat broken up, of course). This occurs even if I have set the S/F/R (Stop/FF/Rewind) EE SEL menu item to EE mode, rather than Tape mode. Also the rewind or ff speed is considerably less than the 32x speed selected in the menu. This does not happen when using a DVCPro tape (i.e., the tape runs at 32x and no picture is output). Before inserting each tape, I of course set the menu for the corresponding tape type (dv or dvcpro).

Is this characteristic of DVCPro decks when playing dv tapes, or does my particular deck have a problem? My concern is primarily increased head and tape wear, as well as the much longer rewind and fast forward times. Thanks in advance.

Carlos Rodriguez · September 29th, 2006, 11:30 AM

my dvcpro decks do the same thing... they play the video at high speed and artifacted. so far they haven't had to be serviced and work fine. I think it might have something to do with the bitrates that the video is recorded at maybe?

Alfred Wirtenberg · September 29th, 2006, 01:19 PM

Carlos -- thanks so much for your response. Good to hear that apparently my machine is functioning as it was designed, and that this dv ff/rewind characteristic has not caused any wear or clogging problems for you. I suspect the reason the decks can't do a pure high speed rewind or fast forward with DV tapes relates to different mechanizations they use for DV vs. DVCPro. For instance, I've read that a DVCPro deck actually uses the record head for playback of DV, rather than the playback head (which is of a different size, optimized for DVCPro). That is part of the reason that DVCPro decks can't record DV. I don't think, though, that bit rates are relevant to this issue; DVCPro (meaning DVCPro25, as opposed to DVCPro50 or DVCProHD) has the same 25 mbps video bit rate as DV.

Thanks very much again for your excellent response. -- Al

Glenn Chan · September 29th, 2006, 04:53 PM

MiniDV has a smaller ?pitch length? than DVCPRO. That is, they cram more video onto a smaller area. This makes the tape a little harder to read back.

When you play back video high speed, it suddenly has to deal with a lot more video for the same amount of time. So the video tape won't get read back as well.

2- I'm not sure why it can't rewind at 32X speed.

September 28th, 2006, 07:40 PM	#1
Alfred Wirtenberg New Boot Join Date: May 2005 Posts: 6	DV Playback in DVCPro Deck I use a Panasonic AJ-D250 deck (DVCPro) to play back full-size DV tapes (Panasonic AMQ's, which can be up to 276 minutes long). Everything works fine, except that during rewind and fast forward I can't prevent the deck from feeding out a high speed version of the video (somewhat broken up, of course). This occurs even if I have set the S/F/R (Stop/FF/Rewind) EE SEL menu item to EE mode, rather than Tape mode. Also the rewind or ff speed is considerably less than the 32x speed selected in the menu. This does not happen when using a DVCPro tape (i.e., the tape runs at 32x and no picture is output). Before inserting each tape, I of course set the menu for the corresponding tape type (dv or dvcpro). Is this characteristic of DVCPro decks when playing dv tapes, or does my particular deck have a problem? My concern is primarily increased head and tape wear, as well as the much longer rewind and fast forward times. Thanks in advance.

September 29th, 2006, 01:19 PM	#3
Alfred Wirtenberg New Boot Join Date: May 2005 Posts: 6	Re: DV Playback in DVCPro Decks Carlos -- thanks so much for your response. Good to hear that apparently my machine is functioning as it was designed, and that this dv ff/rewind characteristic has not caused any wear or clogging problems for you. I suspect the reason the decks can't do a pure high speed rewind or fast forward with DV tapes relates to different mechanizations they use for DV vs. DVCPro. For instance, I've read that a DVCPro deck actually uses the record head for playback of DV, rather than the playback head (which is of a different size, optimized for DVCPro). That is part of the reason that DVCPro decks can't record DV. I don't think, though, that bit rates are relevant to this issue; DVCPro (meaning DVCPro25, as opposed to DVCPro50 or DVCProHD) has the same 25 mbps video bit rate as DV. Thanks very much again for your excellent response. -- Al

September 29th, 2006, 11:30 AM	#2
Carlos Rodriguez Major Player Join Date: Jan 2005 Location: Modesto, California Posts: 206	my dvcpro decks do the same thing... they play the video at high speed and artifacted. so far they haven't had to be serviced and work fine. I think it might have something to do with the bitrates that the video is recorded at maybe?

September 29th, 2006, 04:53 PM	#4
Glenn Chan Inner Circle Join Date: Jun 2003 Location: Toronto, Canada Posts: 4,750	MiniDV has a smaller ?pitch length? than DVCPRO. That is, they cram more video onto a smaller area. This makes the tape a little harder to read back. When you play back video high speed, it suddenly has to deal with a lot more video for the same amount of time. So the video tape won't get read back as well. 2- I'm not sure why it can't rewind at 32X speed.