Corrupt Clips? --Trying to figure out the cause... at DVinfo.net

Matt Irwin · January 25th, 2007, 09:10 PM

I just finished a show shooting 720/24pN onto two 8 GB cards that were rotated through P2 Genie on a PB G4.

3 of the 8 card loads we shot would not import into Final Cut 5.1.2, so I used P2 Log to export those cards as XML. It seems that most, if not all, of the clips have corrupted audio. All four channels constantly cut in and out, and not in unison.
What's more-- at the end of the clip, I see flat grey macroblocking/artifacting-- something I have NEVER seen before with P2 footage.

Attached are screen caps of the artifacting and the audio waveforms from the bad channels (all channels are doing this, not just the XLR-in on CH 1/2).

Any ideas as to the source of the problem? Is it the camera?

Robert Lane · January 26th, 2007, 12:47 AM

There's not enough info to determine if the culprit lies with the camera, P2 Genie or the PB. Here's what I would do to see if the camera/cards themselves are working properly:

- Wipe the card/s and shoot some test footage. If you don't see an "!" symbol in any of the thumbnails then you know the footage as-is in the camera is good. Play the clips back in-camera and see if you notice any issues.
- Connect an external FW drive directly to the camera and offload the clips using HOST mode. Make sure the "verify" function is turned on. If they transfer to the drive without errors then you know the data came out intact.
- Import the clips directly into FCP; don't use P2 Genie or P2 Log to trancode them into QT's or XML's. If you don't see problems there then you can eliminate the camera, cards, FCP and the PB as the source of the problem.
- Take those same clips and use either P2 Genie or P2 Log to transcode them again. See if the same issues return.

This process of elimination should point to where the problem lies; let us know what you find out.

Matt Irwin · January 26th, 2007, 01:42 AM

Thanks Robert. I'll test this in the morning and post my findings.

Perhaps it could be a problem with the on-set workflow we used:
-Card from camera to PB G4's PC card slot.
-Use P2 Genie to transfer the card contents to an external FW400 drive
-Reformat card in the camera during reload
-Ingest into FCP from the external FW400 drive to work drive

January 25th, 2007, 09:10 PM	#1
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	Corrupt Clips? --Trying to figure out the cause... I just finished a show shooting 720/24pN onto two 8 GB cards that were rotated through P2 Genie on a PB G4. 3 of the 8 card loads we shot would not import into Final Cut 5.1.2, so I used P2 Log to export those cards as XML. It seems that most, if not all, of the clips have corrupted audio. All four channels constantly cut in and out, and not in unison. What's more-- at the end of the clip, I see flat grey macroblocking/artifacting-- something I have NEVER seen before with P2 footage. Attached are screen caps of the artifacting and the audio waveforms from the bad channels (all channels are doing this, not just the XLR-in on CH 1/2). Any ideas as to the source of the problem? Is it the camera? Attached Thumbnails __________________ Matt Irwin DP / matt.irwincine.com

January 26th, 2007, 12:47 AM	#2
Robert Lane Go Go Godzilla Join Date: Nov 2004 Location: Scottsdale, AZ USA Posts: 2,788 Images: 15	There's not enough info to determine if the culprit lies with the camera, P2 Genie or the PB. Here's what I would do to see if the camera/cards themselves are working properly: - Wipe the card/s and shoot some test footage. If you don't see an "!" symbol in any of the thumbnails then you know the footage as-is in the camera is good. Play the clips back in-camera and see if you notice any issues. - Connect an external FW drive directly to the camera and offload the clips using HOST mode. Make sure the "verify" function is turned on. If they transfer to the drive without errors then you know the data came out intact. - Import the clips directly into FCP; don't use P2 Genie or P2 Log to trancode them into QT's or XML's. If you don't see problems there then you can eliminate the camera, cards, FCP and the PB as the source of the problem. - Take those same clips and use either P2 Genie or P2 Log to transcode them again. See if the same issues return. This process of elimination should point to where the problem lies; let us know what you find out. __________________ Robert Lane Producer/Creator - Bike Pilots TV

January 26th, 2007, 01:42 AM	#3
Matt Irwin Major Player Join Date: Jul 2004 Location: Los Angeles, CA Posts: 327	Thanks Robert. I'll test this in the morning and post my findings. Perhaps it could be a problem with the on-set workflow we used: -Card from camera to PB G4's PC card slot. -Use P2 Genie to transfer the card contents to an external FW400 drive -Reformat card in the camera during reload -Ingest into FCP from the external FW400 drive to work drive __________________ Matt Irwin DP / matt.irwincine.com