Re: Captions/BTTV (Bug maybe?)

Cyrus Adkisson <lists@xxxxxxxxxxxxxxxxxx> · Thu, 14 Apr 2005 18:51:05 -0400

David Liontooth wrote:
Cyrus Adkisson wrote:
So, I think this closed captioning thing is different from case to 
case. Right now I'm having a situation where I get the garbled output 
(see below), but ONLY when using video capture cards at the same 
time. When they operate independently, they seem fine. Right now it's 
happening with two K-World BT878RF cards, but was also happening with 
two Winfast 2000 Deluxe cards. What in the heck does this? The 
picture and reception are fine. I don't get it.

Interesting -- how do you tell ntsc-cc which card to capture from?
ntsc-cc has a -d option for doing, for instance "ntsc-cc -cp -d /dev/vbi0"
Continuing with this thread, I still haven't fully solved the caption 
garbling issue. It's really frustrating. Right now I have a computer 
(AMD 2500, MSI K7N2 -- have tried several MSI boards in this nforce2 
family --, kingston hyper X ram 512GB, maxtor 250GB hd, FC3 2.6.11 
kernel) with 4 Kworld video cards inside. I was able to configure them 
all correctly and record 4 shows simultaneously with them. The reception 
and picture looked fine on all 4 recordings. I also captured the closed 
captioning during each recording and the info pulled from /dev/vbi1, 
vbi2 and vbi3 were all fine.
As for vbi0, the captions were fine for a few minutes... then suddenly 
became garbled.
TESTS AND RESULTS: (setX = vbiX, videoX, and audioX)
Test 1: (already noted) Tried capturing video and captions on all sets 
at the same time. RESULT: Captions on set0 (video0, audio0, and vbi0) 
become garbled after a few minutes.
Test 2: Tried capturing video and captions on set0 ONLY. RESULT: 
Captions become garbled after a few minutes.
Test 3: Tried capturing video and captions on set0 while also recording 
(*but not using ntsc-cc*) on sets1-3. RESULT: The captions from set0 go 
bad after a few minutes. The problem seems independent of whether or not 
ntsc-cc is running on the other devices and also independent of whether 
or not the other devices are in use.
Test 4: Observed captions from sets1-3 while recording video and 
captions on all 4 sets at once. RESULT: The captions on sets1-3 are 
always fine, no matter what else is going on. Only set0 has problems.
Test 5: Tried other video card brands and models. RESULT: Same results 
as they pertain to captions. Picture and sound vary, obviously.
Test 6: After captions go bad on set0, I thought I'd try to kill the 
ntsc-cc process and restart it to see if the problem cleared up. RESULT: 
It doesn't.
Test 7: After captions go bad on set0, I tried killing the ffmpeg 
process and restarting it to see if the problem cleared up. RESULT: It 
does, temporarily.
Test 8: Tried removing the video0 card so that video1 then becomes 
video0 (in the second slot, not the first). Three sets total. RESULT: 
The *new* video0, which was previously video1 and working fine, gives 
garbled captions after a few minutes. I. E. It doesn't seem to matter 
which slot or which card is being used... only that it is designated as 
set0.
Test9: Tried removing all but one video card. RESULT: More garbled 
captions on the only remaining set, set0.
Test 10: Tried removing both USB audio devices, the PCI audio card, and 
replacing the Kingston HyperX ram with a Kingston valueram (latency of 
2.5 instead of 2.0). (Only one video card installed.) RESULT: More garble.
To be continued, I guess... either my motherboard is bad or something is 
wrong with video4linux. It can't possibly be the devices themselves.
Cyrus
Dave
I think I figured it out (again). Whatever program you're running 
while trying to capture closed captions has to be set to the correct 
frame rate for your capture device. I was using ffmpeg, which sets 
it automatically to 25 fps. All I had to do was put "-r ntsc" or "-r 
29.97" in the command and it started causing ntsc-cc to behave 
correctly.

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