advice on live capture to disk

[Edward Hervey]

Hi,


On Tue, 2014-09-30 at 01:27 -0400, John Bazik wrote:
> I’ve been trying to construct a pipeline to reliably capture a 720p
> camera feed (w/ pcm audio) for 1 to 2 hours and save it to disk.  It
> needs to be sufficiently high quality for me to transcode it later into
> lower resolutions and bitrates for streaming on demand.  I’m capturing
> from a blackmagic intensity pro, on a reasonably powerful 6-core
> machine.  I knock it down from 60fps to 30fps, but I’m otherwise trying
> to preserve the quality and resolution.
> 
> I’ve tried a variety of codecs (theora, x264, mjpeg, huffyuv) and I
> find myself stymied.  I’m not so concerned about compression, though at
> 200GB/hr, raw video is a bit unwieldy.  I spent hours tinkering with
> x264, but could not eliminate weird wavy artifacts.  I could not get
> high quality from theora without dropping frames.  I couldn’t get mjpeg
> to work (openmjpegenc).  I thought I had it with huffyuv (even at
> 96GB/hr), but it, too, dropped frames after a while, though it was
> running at about 25% cpu.  I don’t need a perfect copy, perfect-looking
> is good enough.
> 
> It feel like this should work.  Can anyone point me in the right
> direction?  Am I better off with something like x264, or with huffyuv? 
> When I’m using lossless compression, could I be dropping frames due to
> i/o bandwidth limitations to a standard 7200rpm sata hard disk?

  Raw video on that ... is definitely not going to be possible :) But
the other compressed formats you mention should be fine i/o-wise.

  What version of GStreamer are you using ? What does your pipeline look
like ? Do you get any warnings (GST_DEBUG=2) ? What are those "weavy
artifacts" you mention ?

   Edward

> 
> John
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