Stephen Davies wrote:
On Wed, 7 Nov 2001, Justin Schoeman wrote:
Could I ask you to give NVrec a try, using the FFMPEGrec front-end. I
haven't had much feedback yet on audio synch for this frontend...
I have the 20011101 version; I'm using it into bttv 0.8.28's v4l2
interface with btaudio. Some minor changes were needed on both sides to
get them to play - so I suppose that this is a combination others haven't
tried. (I will send the patches, but read on)
Thanks, I would appreciate that.
I haven't done thorough tests - and will try to this weekend. But my
first impression is that sync isn't as "sorted" as I expected. And
certainly more problems with btaudio. One thing I notice is that the
"Warp" sits at 0 when capturing from the SBLive, and cycle 37 -1 -17 -23
with the btaudio. Perhaps this is a problem with my GETISPACE patch for
btaudio, perhaps its normal and to do with how btaudio packetizes.
Interesting... Is it not possible to get an accurate byte-count from
btaudio?
But I'd prefer to investigate properly.
A question - how can I be sure that sync issues are at capture and not an
mplayer playback problem...?
The other thing I don't understand about ffmpeg is: why does sync go way
out when I use ffmpeg to process existing mpeg1 files that I captured with
mp1e? Is this about some incompatibility with PTS info? Perhaps ffmpeg
ignores that?
I am not sure. I have not looked at ffmpeg in much depth yet. One
thing I do know is that NVrec send precisely the correct ratio of audio
to video data to maintain synch. If you do get synch drift (at least
more than the resolution of the Bt848 audio input timer), then it is
likely an ffmpeg (or my interface to it) problem. The fact that it
messes up transcoding of mp1e streams seems to indicate that the fault
lies with ffmpeg...
-justin
