[mythtv] [mythtv-commits] Ticket #1356: DTVRecorder::FindKeyframes in 0.19 causes video gltiches in firewire recordings

Jim Westfall jwestfall at surrealistic.net
Sat Feb 25 17:15:20 UTC 2006

Daniel Kristjansson <danielk at cuymedia.net> wrote [02.25.06]:
> On Sat, 2006-02-25 at 08:30 -0800, Jim Westfall wrote:
> > I did some poking around libraw/libiec61883 last night and I dont think we 
> > need to do any buffering in myth.  libiec61883 has libraw/kernel setup a 
> > 1000 packet buffer.  We have access to change the size, but if the buffer 
> > gets completely full we should get drop packet notices.
> Hmm, maybe the notification is broken? Or the people reporting the
> problem are ignoring these messages?

There is a chance we arent getting some of the notifications from
iec61883 via our callback function.  I added the following locally at the 
end of StartRecording that should tell for sure.

    VERBOSE(VB_IMPORTANT, QString("FirewireRecorder: Total Dropped %1")

so far I havent had any drops, tho I dont get glitches every often.

> There is no way 188000 bytes is enough of a buffer for HDTV capture...
> We use almost 10 MB for other HDTV capture methods, and the minimum
> we allow people to set it to via the UI is almost 5 MB...

The buffer is 1000 firewire packets which makes it about 2 MB.


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