Few questions

  • guhlda

    guhlda - 2011-07-25


    I have a few questions:

    1. Do you confirm that dvs_sdi is able to capture with DVS LTC (separate XLR port) as timecode source ? I'm still waiting for the LTC add-on card and urgently need that information..

    2. What is the latency of dvs_sdi caprute, in terms of frame, field, other..

    3. Why is playout -dvs-buf size minimum 8 frames ? Is it possible to go down to 1 frame or field ? Is it a hardware or software constraint ?

    Thank you

  • John Fletcher

    John Fletcher - 2011-07-26

    1. yes
    2. latency from capture to what?
    3. This is max usage of hardware output buffer.  I don't think reducing it will make any difference to output latency.

  • guhlda

    guhlda - 2011-07-26

    1. fine2. Latency: from capture (incoming signal) to availability in dvs_sdi share memory. Similarly to output buffer where you have to fill 8 buffers before starting (thus 8 frames latency), does input buffer have a buffer depth we cannot avoid ?

    3. You mean player forces to use the maximum buffer depth ? Or is it a hardware lower limit ?

    Thanks a lot

  • John Fletcher

    John Fletcher - 2011-07-26

    Capture to availability in shared memory would generally be less than two frames,  The hardware does have an input buffer so dvs_sdi can let a few accumulate on the card before reading them out if necessary (e.g. it briefly runs slow for some reason) but usually they are read out as soon as they are available.

    On playout, I'm pretty sure the card doesn't wait until the hardware buffer is full before outputting any video.  The only effect of a larger buffer size would be when you seek to a new position, in which case the frames already in the buffer would be output before the frames from the new position.


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