[mythtv-users] Choppy Video solved

[John F DeLuca]

I finally resolved my studder problem (choppy audio/video) with Mythtv. 
The solution was to ensure I had video drivers capable of xvideo.  That 
may seem obvious to most of you, but to this newbie, it was a revelation.  
I've noted here in case anyone else is experiencing choppy video as 
something to check.

I am using Jarod's (awesome) guide with Fedora Core 1.  Since I have a 
beefy system (Athlon XP 1800+, 120GB drive, 1.5GB Ram), and hardware 
en/decoding (PVR-350), I couldn't figure out why i had 
jittery/choppy/studdery video/audio when either watching live tv and/or 
watching recorded TV.  My CPU would hit 100% when attempting to do these 
which is the cause of the choppiness.  But what caused the 100% CPU, 
especially given that I have the PVR350 which should handle the 
en/decoding.  I saw a post which helped trigger the lightbulb icon over my 
head.  It turns out, my problem isn't with the video capture card, but the 
graphics card.  While it's capable of xvideo (not even sure what that is 
but it's important to smooth video I'm guessing), I didn't have the 
requisite driver to ensure it was rendering Xv.  While I did follow 
Jarod's guide, I skipped the section titled "8. Get and install video card 
drivers for TV out" because I wasn't outputting to a TV, but rather to an 
LCD screen.  Jarod accurately notes that this step is optional, but I 
found it to be critical to me for smooth as gravy video. 

To determine if my system was using Xv, I typed this at a command prompt:

#  xvinfo

and was returned  the following:

X-Video Extension version 2.2
screen #0
no adaptors present

After following Jarod's guide to install the video card drivers for TV 
out, the same command returned this (and smooth video):
X-Video Extension version 2.2
screen #0
  Adaptor #0: "NV04 Video Overlay"
    number of ports: 1
    port base: 77
    operations supported: PutImage
    supported visuals:
      depth 16, visualID 0x21
      depth 16, visualID 0x23
      depth 16, visualID 0x24
      depth 16, visualID 0x25
      depth 16, visualID 0x22
      depth 16, visualID 0x26
      depth 16, visualID 0x27
      depth 16, visualID 0x28
    number of attributes: 4
      "XV_DOUBLE_BUFFER" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 1)
      "XV_COLORKEY" (range 0 to 16777215)
              client settable attribute
              client gettable attribute (current value is 2110)
      "XV_AUTOPAINT_COLORKEY" (range 0 to 1)
              client settable attribute
              client gettable attribute (current value is 1)
      "XV_SET_DEFAULTS" (range 0 to 0)
              client settable attribute
    maximum XvImage size: 2046 x 2046
    Number of image formats: 4
      id: 0x32595559 (YUY2)
        guid: 59555932-0000-0010-8000-00aa00389b71
        bits per pixel: 16
        number of planes: 1
        type: YUV (packed)
      id: 0x32315659 (YV12)
        guid: 59563132-0000-0010-8000-00aa00389b71
        bits per pixel: 12
        number of planes: 3
        type: YUV (planar)
      id: 0x59565955 (UYVY)
        guid: 55595659-0000-0010-8000-00aa00389b71
        bits per pixel: 16
        number of planes: 1
        type: YUV (packed)
      id: 0x30323449 (I420)
        guid: 49343230-0000-0010-8000-00aa00389b71
        bits per pixel: 12
        number of planes: 3
        type: YUV (planar)

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