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# Vtr

The Vtr keyword identifies video tape recorders that can be used for clip I/O. You can uncomment VTRs of different video formats. Any enabled VTR can be selected for a project, regardless of the project's video I/O timings.

You can also use the Vtr keyword to identify supported High-Speed Dual-Link (HSDL) devices for clip I/O, such as telecines. HSDL devices appear as separate entries in the list of supported decks for the Vtr keyword.

The Vtr keyword uses the following syntax

Vtr <protocol>, <name>, <input_format>, <timing>,<colorspace_mode>, <output_format>, <output_sync>, <serial_port>, <timecode_type>, <video_output_delay>, <video_input_delay>, <pre_roll>, <post_roll>, <audio_input_delay>, <audio_output_delay>, <video_precision> [, <cueup_mode>, <TC_transition_delay>, <edit_on_delay>, <edit_off_delay>, <vtr_command_delay>]

Where: | Is:
--- | ---
<protocol> | The VTR control protocol (SONY, BTS, BVW50, TASCAM, or NONE).
<name> | The name by which you want to identify the VTR in the Input Clip and Output Clip menus (D1, DigBeta, D1 BTS, D5, and DVCpro, for example).
<input_format> | The video input format. Set to Serial1 to input using a single-link (4:2:2) connection from a device. Set to SerialDual to input using a dual-link (4:4:4) connection from a device.
<timing> | The I/O timing associated with the video standard of the VTR (NTSC, PAL, or HD, if applicable).
<colorspace_mode> | The mode that indicates whether colourspace conversion and/or headroom is required for clip I/O. See Configuring Colourspace Conversion for Device I/O.
<output_format> | The video output type. Set to Serial1 to output using a single-link (4:2:2) connection to a device. Set to SerialDual to output using a dual-link (4:4:4) connection to a device.
<output_sync> | The sync source used for clip output. For AJA cards, the possible values are STANDALONE, HOUSE, or DIGITAL1.
<serial_port> | The serial port to which the VTR is connected. It takes the value AJA:0:1 for workstations using an AJA KONA 3G or OEM-2K card.
<timecode_type> | The timecode type to be returned by the VTR (Auto, LTC, or VITC).
<video_output_delay> | Video output delay in frames.
<video_input_delay> | Video input delay in frames.
<pre_roll> | Preroll in frames or seconds: Use integers to specify preroll in frames. Use decimals to specify preroll in seconds.
<post_roll> | Postroll in frames or seconds: Use integers to specify postroll in frames. Use decimals to specify postroll in seconds.
<audio_input_delay> | The offset value to have sync audio with video on input. Integer units represent frames; this delay should be 0 by default.
<audio_output_delay> | The offset value to have sync audio with video on output. Integer units represent frames; this delay should be 0 by default.
<video_precision> | The precision of the video interface (8 or 10 bits).
<cueup_mode> | The method by which the VTR is cued. This parameter is optional. Use vtrcueing to make the application use the VTR Cue command directly to cue the VTR. Use vtrff if using vtrcueing causes the VTR to react slowly when cued, such as with a Betacam SP™.
<TC_transition_delay> | The delay in milliseconds after a vertical sync, before requesting the VTR timecode. This value should only be set or changed with the help of technical support. NoteThe value '99' is a special case to be used strictly with HDCAM-SR/720P and AJA. It is not to be used in other circumstances unless specified by technical support.
<edit_on_delay> | The delay in frames before the edit sync point to send the ON command. This parameter is optional and it applies only to BVW50.
<edit_off_delay> | The delay in frames before the edit sync point to send the OFF command. This parameter is optional and it applies only to BVW50.
<vtr_command_delay> | The delay in milliseconds before the application sends certain commands to the VTR. This parameter is optional, but useful for older VTRs such as the BTS.

NoteThe init.cfg file contains a comprehensive list of Vtr keyword examples for supported devices. In most cases you just have to uncomment the lines for the device that you want to use. In some cases minor changes to parameters are required.

Configuring Colourspace Conversion for Device I/O

When you set the input or output format for a device in the Vtr keyword, you should also specify its colourspace conversion method using the <colorspace mode> parameter. The supported conversion methods depend on whether a single-link or dual-link connection is used for I/O with the device. The following table shows the colourspace conversion methods that are available for single-link and for dual-link I/O connections.

Colourspace Conversion Method | Supported for Single-Link Serial (4:2:2) I/O | Supported for Dual-Link Serial (4:4:4) I/O
--- | --- | ---
YCbCR -> RGB | Yes | No
YCbCR -> RGB + Headroom | Yes | No
No Conversion | No | Yes
No Conversion + Headroom | No | Yes

#### Topics in this section

- Configuring Colourspace Conversion for Device I/O