Whats a drop-Out?

[Kevin Lewis]

Can someone please explain exactly what a drop out lloks like. My camera has under 10 hours on it and I only use the Canon Master tapes and i've never noticed anything strange on my recording other than what apppears to be an occasional skip. Put if I rewind and play back the skip is no there. This is not a drop out is it?

[Mark Boyer]

A drop out (to me) sounds like a static hit (like when your car radio looses the station). It can also sound like a silence in the audio due to a bad audio cord or old batteries. In data transmission, a momentary loss of signal that is due to system malfunction or excessive noise.

A dropout is a small loss of data in an audio or video file on tape or disk. A dropout can sometimes go unnoticed by the user if the size of the dropout is small. Error correction schemes can compensate for the dropout by filling in data where a dropout is detected. With a larger section of missing data, the user will see or hear the error.

The reason for a dropout can be bad tape stock, a bad block on a hard disk, dirt, the age of the tape or disk, or something else. Older tapes, especially those dating to the analog era, are more susceptible to dropouts as they age. The magnetic particles on the tape become detached from the backing material, resulting in what is commonly known as shedding. Larger dropouts can be quite serious. On the master tape of a vintage recording, a dropout could be large enough to render a selection unusable. In a video studio, a dropout on the SMPTE Time Code track could cause the machines slaving to the Time Code track to stop momentarily.

[Daniel Epstein]

Kevin,
No I don't think you would call this a dropout although it may be a defect in the recording or the cameras ability to playback the recording.. Many people use dropout as general term for seeing picture defects in playback.

A dropout is an old video term which indicated a small loss of picture on playback of a tape. It would often appear black and disappear after a few frames. The rest of the picture would be unaffected. Many people would say this is the result of a defect in the oxide which contained the recording. Sometimes on a bad recording you would have multiple dropouts on the same frame or many over a period of time. The first minute of a tape and the last would often have the most. All tapes would have some and electronic circuits called Drop out Compensators would attempt to make them invisible. If the camera or deck doing the recording was not in good shape the dropouts would appear in playback of the recording. If only the playback deck was the issue then the issue was more salvageable. Different tape had different formulations and getting things to match up correctly was a difficult task. Worn out video heads often give recordings which have more problems then newer heads which is often misdiagnosed as dropouts.

In todays mostly digital world dropouts might not appear in the same way as the data is recorded in a different manner than in the analog way. Picture defects on playback still might be tape based but most likely would not be described as dropouts but more likely as errors in the data stream. Blocks of the image freezing are more likely in the digital domain with a tape defect than just a small speck of black while the rest of picture is fine.

[Kevin Lewis]

Thanks for the info guys!