SP vs. LP (vs. SDL ?)

[Syed Mahmood Ahmed]

I started the thread below in the 'long black line' section, but got no response ... so maybe posting it here may generate more interest :)

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Hi,
I am not into professional Video editing/production, but I have recently read the DV Specs (IEC 61834). So u can say that my interests are mostly academic, but I do not have much practical experience. Only fiddled with a few consumer camcorders.

The standard does not talk about the LP mode (or maybe I did not read carefully), but the few consumer camcorders I have come across allow options to record in SP/LP mode. Are these two recording modes fully compliant to the "SD" spec (IEC 61834-2)? It seems to me that SP recording is fully in accordance with the "SD" spec, and LP is not ... and the difference is in the error codes, system (aux) information, etc. (i.e., the audio/video coding of the two modes are the same). Will appreciate comments/feedback on this

A google search on DV and SDL shows that a few Canon Camcorders support the SDL format (IEC 61834-6). How popular is the SDL format, and do the industry folk think that it will proliferate?

[Ken Tanaka]

I am not an authority on technical engineering standards for video recording. But here's the scoop that matters on this subject.

"SP" mode is standard. That is, data is laid down in a specific format and the tape is moving past the heads at a specific speed.

"LP" mode is more of a marketing standard. While the data is laid onto the tape in the same format (to my knowledge) the tape speed might not always be consistent across manufacturers. LP footage recorded on one camera might not be replayable on another camera, even within the same brand and model.

Since the tape is moving slower during LP mode recording, the integrity of every millimeter carries greater weight in the integrity of the overall footage. There is far less opportunity for error correction and far greater susceptibility to minute tape flaws.

In the final analysis, with the cost of tape being so low, it's hard to make a defensible case for using LP mode, certainly for anything of significance. Some have argued that they need LP's longer recording time when shooting events that cannot be interrupted for tape changes. To them I would recommend that they invest in a Firestore FS-3 or a similar disk recorder.

[Syed Mahmood Ahmed]

Thanks for the reply Ken. Your scoop is indeed valuable.

I'll appreciate if u can give me your opinion about the "SDL" format

[the DV spec talks about three formats: SD (standard definition), HD (high definition) and SDL (some sort of low resolution; i.e., more recording time on the same tape) ].

As i said in my earlier post, from a search on the web, it seems that Canon is the only brand that supports the SDL format.

[Ken Tanaka]

Re: SDL, I don't know. The only "SDL" I've seen within a video context relates to display on a computer screen ("Simple DirectMedia Layer").