PsF’s missing workflow, Part 4: file-based HD video recorders

TecnoTur on PVC by Allan Tepper In part 1 of PsF’s missing workflow, we introduced the new terms benign PsF and malignant PsF (Progressive Segmented Frame), reviewed their vital importance and fragility in post-production, and clarified the PsF status of two Panasonic professional AVCHD/AVCCAM cameras. In part 2, we covered the PsF status of the Canon XA10 professional AVCHD camera. In part 3, we clarified the PsF status of Sony’s professional AVCHD/NXCAM cameras. Now, in part 4, we’ll cover some file-based recorders (from manufacturers like AJA, Átomos, Blackmagic, Convergent Design, Datavideo, and Sound Devices), their PsF status, and their purpose in your system and workflow.

About file-based portable HD video recorders

File-based portable HD recorders exist nowadays basically for two reasons: Either to make a superior recording than that could be possible inside of a camcorder’s own recorder, or to record the output of a video mixer (“switcher”), whether be it superior or equivalent quality to what might have been recorded internally in the cameras used. When I say superior, I mean either a 10-bit recording instead of an 8-bit recording, a 4:4:4 or 4:2:2 recording instead of a 4:2:0 recording, or a less compressed (or uncompressed signal). When I say that a recorder goes “up to” 10-bit, what I mean is that it records with 10-bit quality as long as the source being fed is truly 10-bit, not a 10-bit signal which has been derived from an 8-bit signal, as I have covered in more detail in several prior articles. When fed a signal that is 8-bit (over HDMI) or 10-bit derived from 8-bit (over HD-SDI), the recorder makes a 10-bit recording that has 8-bit quality. When I say nowadays, I mean that because all new development in cameras I see is tapeless. However, with a camcorder that records HD on tape, there is one more potential benefit of recording on an outboard file-based HD recorder: drastically decreased ingest time.

The terms Benign PsF and Malignant PsF

The terms benign PsF and Malignant PsF were introduced in Part 1 of this series called PsF’s missing workflow.

Recording from an HD-SDI source

Some portable, file-based HD video recorders have both HD-SDI inputs and HDMI inputs, some only have HD-SDI, and some only have HDMI inputs. When connected via HD-SDI and receiving signals already designated as 23.976PsF, some of the recorders with this type of signal will automatically know to record the signal as pure progressive. However, when receiving 1080/25PsF or 1080/29.97PsF over HD-SDI, the recorders have no way to distinguish them from interlaced signals, so if you intend to record 1080/25p or 1080/29.97p, you must go into the recorder’s menu to request it (if the seting exists). Otherwise, you’ll end up with the negative side effects of Malignant PsF described in Part 1 of this PsF’s missing workflow series. The way to make the request of the recorder varies among manufacturers (if possible at all), as I’ll cover ahead in this article. read more...