Anybody Worked With DVCPro in Ulead MediaStudio Pro 8?

[Jerry Jones]

Do you believe everything the Sony rep tells you? All DV recording has locked audio. It's only when transferred to DV type 2 avi format that it becomes unlocked. It is part of the DV spec that there are synch blocks in each audio sector, just as there are in video sectors. For NTSC, each track, starting at line 1, has 9 audio synch blocks, each handling 72 bytes of data. The samples are interleaved within a frame. There are even 5 error correcting audio synch blocks, in the event of slippage. Let me see, what is DVCAM saying? Oops! Exactly the same!

This is a damn good reason for keeping it DV type 1, provided it is compatible with your hardware.

No, Brian, but I also don't believe everything you tell me.

If you can point to one -- yes just one -- reputable technical document to confirm what you've just written about MiniDV and locked audio then I'll eat my hat.

But it's contrary to what I've been told and contrary to what I've read in numerous technical articles.

Jerry Jones

http://www.jonesgroup.net

[Jerry Jones]

1. ADOBE's definition of "locked" audio:

http://tinyurl.com/vvp9x

2. Adam Wilt doesn't say that DV Type 1 is "locked." He does say that because the audio is interleaved with the video there is no "drift" with DV Type 1. Still, ONE SHOULD NOT INFER, therefore, that consumer DV camcorders record "locked" audio. They don't.

http://tinyurl.com/y56rk5

To say that DV Type 1 is "locked" confuses the definition. The terms "locked" and "unlocked" refer to the way audio is recorded by MiniDV vs. "pro" camcorders such as DVCam.

Jerry Jones

http://www.jonesgroup.net

[Brian Ellis]

With locked audio, the audio sample clock is precisely synchronized with the video sample clock -- an exact number of audio samples is recorded per a set number of video frames.

This is exactly what I said. What Premiere are talking about is the avi file downloaded from the cam. What is on tape - and this is what I'm talking about - is exactly as I described and cannot deviate from the standard. The ONLY difference between DVCAM and DV25 is in the track width. How you transfer it to hard disk is variable, according to the codec that is used. For a more detailed description see IEC 61834 for DV25 or the more recent SMPTE 314M and 370M for DV25, 50 and 100. SMPTE 314M, which is the standard used for DV25, the audio sampling is locked to the video frame frequency by a mandatory 0 bit placed in the PC1 7th bit of the AS pack of the Audio Auxilliary Data source pack. In the earlier IEC spec, it was not mandatory, but was usual. What I'm not absolutely clear on is whether the 0 bit in PC1D7 is mandatorily set when using SMP010 and QU001 (32 kHz 12 bit non-linear sampling): if not, then I agree that the audio is not locked, but for SMP000/QU000 (48 kHz, 16 bit sampling), there is absolutely no reason why it isn't locked.

[Jerry Jones]

This is exactly what I said. What Premiere are talking about is the avi file downloaded from the cam. What is on tape - and this is what I'm talking about - is exactly as I described and cannot deviate from the standard. The ONLY difference between DVCAM and DV25 is in the track width.

Nonsense.

Adobe -- when making references to "locked" vs. "unlocked" audio -- is talking about DEVICES and not DV Type 1 or DV Type 2:

Digital video (DV) recording DEVICES record audio in a locked or unlocked format. Some devices record audio in only one format, and some provide a choice. This document describes locked and unlocked audio and explains how Premiere works with either format.

Jerry Jones

http://www.jonesgroup.net