[gst-devel] Dropped frames at gstbaseaudiosrc

[Sebastian Voecking]

Hello!

> Why the changes:
> * it seems my (not that old) hardware can't keep up with real-time theora
> encoding (or I am doing something wrong in the theora area)
> * queue has been dropped because the mmap'ed buffers that v4l2src output
> (somehow??) choke my (threading) performance further down (strange but real)

I dropped theora and tried other codecs and the only pipeline I found
which produces a good video with audio was

gst-launch-0.10 v4l2src ! jpegenc ! avimux name="avi" alsasrc
device=hw:1,0 ! audio/x-raw-int,rate=32000 ! queue ! avi. avi. !
filesink location=test.avi

Unfortunately is the result AVI file huge. And totem can only play the
first 30 minutes of it.
Other codecs resulted in a choppy video and audio or a far to fast
running video.

> What to do about this;
> * newer v4l2src (queue-size) allows allocating more frame buffers; should
> prevent dropping at that level.  In turn, however, this will lead to even more
> "clustering" in the timestamps of the output buffers (and encoder complaints)
> * this "clustering" can be somewhat counter-acted by using the videorate
> element.  Although that should then result in pretty good audio-video sync
> (without complaints), video may be a bit choppier, since videorate will respond
> to the "clustering" by (lot of) dropping frames one moment, and (lot of)
> duplicating frames other moments.

I tried upgrading by hand but afterwards my tv card (BTW it's a Terratec
Cinergy 400) didn't work at all with v4l2src. It complained always that
it could not negotiate a format. Now I went back to 0.10.5. So I guess I
am stuck with the old version.

Regards,
Sebastian