Beyond Pressing Play: Tools and Strategies for High Quality Reformatting of Field Recorded Materials

Andrew Weaver and Libby S. Hopfauf

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Spectrogram: X axis is time, Y axis is frequency, Color is Intensity

Higher Frequencies Boosted On Recoding

Then Reduced on Playback

Left to right:original, lowered HF, raised HF

Before (L) and after (R) removal of felt pad

Note slight loss of high frequencies

Sticky tape? Sticky pad?

"Once the demagnetizer is around 70 mm away from the head, it doesn't matter how you move it around and turn it off."

McKnight, J. G. (2005, February). Demagnetizing A Tape Recorder. Retrieved from https://web.archive.org/web/20080723125605/http://home.flash.net/~mrltapes/mcknight_demag.pdf

Resources

MRL Paper on Head Demagnetization

Spectrogram in Audacity

What is DV?

What is DV?

  • Originally known as DVC (Digital Video Cassette)
  • 1/4-inch metal evaporate tape
  • High quality digital video
  • 4:1:1 in 525-line (NTSC); 4:2:0 in 625-line (PAL)

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

DV Compression

  • Discrete Cosine Transform (DCT)
  • Lossy
  • Intraframe compression
  • Adaptive interfield compression
  • Approx. 12 GB per hour of video

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

Data Stream

  • Provenance metadata contained within DV videos
  • Contains information for the following:
    • Video/Audio
    • Subcode (including timecode)
    • Insert and Track information (ITI)
    • Error correction

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

Variants

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

Reformatting Equipment

Connection

  • IEEE-1394
    • “Firewire” (Apple)
    • “i.Link” (Sony)
  • SMPTE 259M SDI (serial digital interface)

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

Capture Software

  • Live Capture Plus
  • Adobe Premiere Pro
  • SDK Tools

Artifacts and Defects

  • Mosquito noise
  • Quilting
  • Motion blocking
  • Dropouts
  • Banding/striping
  • Corrupt timecode

Open QC and Troubleshooting Tools

  • A/V Artifact Atlas
    • Resource for identifying errors and anomalies in video files
  • DVAnalyzer
    • Error detection and quality control
    • Temporal metadata reporting

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

DVAnalyser case studies

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

Application and experience at SMA

Additional Resources

Image: DV tape sizes 2 (Uploaded by grm_wnr) CC BY-SA 3.0 via Wikimedia Commons

1/4" Field Recordings: Watch out for Sync/Neopilotone!

(AKA Mistakes Were Made)

Image: DRs Kulturarvsprojekt from Copenhagen, Danmark (Nagra IV-S tape recorder Uploaded by palnatoke) CC BY-SA 2.0 via Wikimedia Commons

Two sine waves recorded on center of tape in inverse to each other.

If played back on correct head configuration, sound cancels out.

If played back on wrong head configuration, audible hum is introduced!

Image: DRs Kulturarvsprojekt from Copenhagen, Danmark (Nagra IV-S tape recorder Uploaded by palnatoke) CC BY-SA 2.0 via Wikimedia Commons

Problematic as many Archives have two track machines. This will cause hum for many sync recordings!

Image: DRs Kulturarvsprojekt from Copenhagen, Danmark (Nagra IV-S tape recorder Uploaded by palnatoke) CC BY-SA 2.0 via Wikimedia Commons

Resources:

Image: DRs Kulturarvsprojekt from Copenhagen, Danmark (Nagra IV-S tape recorder Uploaded by palnatoke) CC BY-SA 2.0 via Wikimedia Commons

Questions?