Difference Between LP and SP Recording with DV Camera

[rkr1958]

I have a Sony TRV-320 DV Camera. My question, is there a difference in the quality of the video if recording using SP (~60 minutes per tape) versus recording using LP (~90 minutes per tape)? Is the LP recording more lossy than the SP? If so, how would this loss translate to video captured from the camera?

Thanks in Advance.

[Nelson37]

Yes, it will look worse. What did you expect?

[sammie]

Actually, it's an interesting question. Yes, it does look worse, especially when you are using it as a camera. But, if you are using it as a capture device for transfering VHS tapes the souce isn't good enough that I can't tell any difference between SP and EP. I sill always use SP kind of just on general priciples, if it looks better for one thing it has to be better for everything, but..... it would be nice to know exactly what the difference is. I presume just a lower bit rate.

[rkr1958]

Yes, it will look worse. What did you expect?

Sorry, let me be more percise. When you record at LP versus SP are you recording the same data at a different number of bytes per inch (bpi) on the tape. That is, same data but packed tighter on the tape.

[Jester700]

It shouldn't look any worse. It's the same data. However, since it's recorded at a tighter pitch, tracking must be spot on. This is why you shouldn't use the tape in another camera (likely to be a small variation in alignment) or store over time (same reason). It will also be more susceptible to dropouts, so digital glitches are more likely. But provided none of these happen and the info plays back properly, there's no quality disadvantage.

[Xesdeeni]

The technical phrasing is that there are "more error bits." The data is the same, but the odds of a bit being lost increase at the slower speed. Bits are normally lost due to flaws in the tape. However, the nature of magnetic media is that the magnetic particles actually fall off as they age. This means as tapes age, bit errors increase. DV can deal with a few dropped bits, so for short-term storage, there will probably (almost none in my experience) be no noticable degradation. But I would not recommend the longer play time for long-term archival storage of valuable footage.

Xesdeeni

[ungern]

In SP you can have two audio tracks (dubbed on later) while in LP the cam uses more of the tape's width for video. I use LP all the time, and do not think that I lose noticeable quality. After all, if you make a DVD of the film for example, then you lose much more quality right there!!

[Xesdeeni]

In SP you can have two audio tracks (dubbed on later) while in LP the cam uses more of the tape's width for video.

My camcorder allows 2 tracks of 16-bit 48KHz audio or 4 tracks of 12-bit 32KHz audio in either SP or LP modes (the second 2 tracks dubbed in later).

I use LP all the time, and do not think that I lose noticeable quality. After all, if you make a DVD of the film for example, then you lose much more quality right there!!

I have experienced an increase in bit errors with LP mode. A few dropped bits are only visible if you look closely at a still frame. They show up as some checker-boarding or color blocking. But more dropped bits cause huge areas of problems. My camcorder (and I believe it is following some recommendation) shows bands of the last known good frame when encountering large numbers of bad bits. So if the video is moving, you get large horizontal strips of non-moving picture (of course, if the image isn't moving, the errors might go unnoticed). Although this is rare, it is quite a bit worse than DVD MPEG encoding artificacts .

Xesdeeni