[mythtv-users] Mythbuntu running 7.10/ 0.21: Cannop open /dev/video0

Matt Emmott memmott at gmail.com
Mon Apr 14 01:36:34 UTC 2008


I built a Mythbuntu box recently, updating it via Synaptic to Myth .21. I
can get about 5 HD channels over firewire but no 'clear' channels, so I
decided to try and use the inputs on my PVR-150 card, which has been in the
system since I built it. After removing firewire, adding the Hauppauge card
as an input and tuner source, and scanning the channels, I tried watching
LiveTV but only got a blank screen. I downloaded and installed TVTime to
test the tuner outside of Myth and when I try launching TVTime I get the
message "ivtv: Invalid argument Cannot open capture device /dev/video0".
/dev/video0 does exist, and it appears to be working at least enough that
scanning for channels in Myth returns valid analog channels - ie, the
channels it finds match up with what I can get on a cable-ready TV.

Finally, I was able to cat /dev/video0 to an mpg file and play it back with
Mplayer both as myself and via sudo, which I found odd since if I can get
delicious shrimp from Long John Silver's to display on my screen via that
route, why not via MythTV or TVTime?

I did some poking about and may or may not have found important information,
but it's above my skill level so I was hoping somebody here could help me
out. Here's what I think is relevant info (magic is the machine's hostname):

matt at magic:~$ dmesg | grep ivtv
[   30.025993] ivtv:  ==================== START INIT IVTV
====================
[   30.025999] ivtv:  version 1.0.0 (2.6.22-14-generic SMP mod_unload 586 )
loading
[   30.026534] ivtv0: Autodetected Hauppauge card (cx23416 based)
[   30.028884] ivtv0: Unreasonably low latency timer, setting to 64 (was 32)
[   30.687148] ivtv0: loaded v4l-cx2341x-enc.fw firmware (4106434152 bytes)
[   30.899982] ivtv0: Encoder revision: 0x02050032
[   30.899985] ivtv0: Recommended firmware version is 0x02060039.
[   30.956284] ivtv0: Autodetected Hauppauge WinTV PVR-150
[   30.956286] ivtv0: reopen i2c bus for IR-blaster support
[   31.020034] tuner 1-0061: chip found @ 0xc2 (ivtv i2c driver #0)
[   31.174629] cx25840 1-0044: cx25841-24 found @ 0x88 (ivtv i2c driver #0)
[   34.545488] wm8775 1-001b: chip found @ 0x36 (ivtv i2c driver #0)
[   34.899612] ivtv0: Registered device video0 for encoder MPEG (4 MB)
[   34.899928] ivtv0: Registered device video32 for encoder YUV (2 MB)
[   34.900279] ivtv0: Registered device vbi0 for encoder VBI (1 MB)
[   34.900501] ivtv0: Registered device video24 for encoder PCM audio (1 MB)
[   34.921793] ivtv0: Initialized Hauppauge WinTV PVR-150, card #0
[   34.921832] ivtv:  ====================  END INIT IVTV
====================



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