Hidden Data Errors? at DVinfo.net

David Kennett · May 9th, 2004, 06:13 PM

I'm still using the KDDI software, and discovered what I believe to be a problem with fully correctable errors in the m2t data stream. I have been making frame accurate edits with this software, so I know it can be done. On occasions some unusual problems would occur. In a couple of cases, several frames would repeat at the beginning (or end) of a title key. Sometimes a flash frame of blocky video would appear at the beginning of a dissolve. The preview was perfect, but the edit was not!

It occurred to me that this always occurred at the junction of re-rendered video and raw camera video. On a whim I dropped a blank title over the material just before a particularly troublesome key. The problem was GONE!

My guess is that there were considerable data errors in this region of the tape. The errors were fully corrected during the normal GOP sequence, but when this was disrupted by the beginning of a key or effect, the software had trouble creating a new GOP while doing error correction.

By adding an empty title key, I forced it to re-render ALL the material in the vicinity of the troublesome key. Now that I think back to some of my early DV editing, I probably ran into this problem before. I had to remove some video recorded onto an obviously bad chunk of tape. Since I wanted to use as much video as possible, I used some which had audio breakup. I thought this would not be a problem since I was not using location audio. The new audio I added IN THE COMPUTER broke up also during that same video. I think forcing it to re-render would have done it!

Anyone have anything to add? Hope this helps!

May 9th, 2004, 06:13 PM	#1
David Kennett Major Player Join Date: Jul 2003 Location: North Ridgeville, Ohio Posts: 407	Hidden Data Errors? I'm still using the KDDI software, and discovered what I believe to be a problem with fully correctable errors in the m2t data stream. I have been making frame accurate edits with this software, so I know it can be done. On occasions some unusual problems would occur. In a couple of cases, several frames would repeat at the beginning (or end) of a title key. Sometimes a flash frame of blocky video would appear at the beginning of a dissolve. The preview was perfect, but the edit was not! It occurred to me that this always occurred at the junction of re-rendered video and raw camera video. On a whim I dropped a blank title over the material just before a particularly troublesome key. The problem was GONE! My guess is that there were considerable data errors in this region of the tape. The errors were fully corrected during the normal GOP sequence, but when this was disrupted by the beginning of a key or effect, the software had trouble creating a new GOP while doing error correction. By adding an empty title key, I forced it to re-render ALL the material in the vicinity of the troublesome key. Now that I think back to some of my early DV editing, I probably ran into this problem before. I had to remove some video recorded onto an obviously bad chunk of tape. Since I wanted to use as much video as possible, I used some which had audio breakup. I thought this would not be a problem since I was not using location audio. The new audio I added IN THE COMPUTER broke up also during that same video. I think forcing it to re-render would have done it! Anyone have anything to add? Hope this helps! __________________ Dave