20 May
2011
20 May
'11
2:24 p.m.
hi,
i have been doing videostreaming now number of times and somehow i
always run into the same peculiar problem.
whenever there is more action on camera, especially zoomins and a lot
of audio (like bass and distorted vocals for example), the stream starts
to continously skip chunks of video stream of about 0.5-1 second,
every 0.5-1 second.
does anyone had a similar problem or knows what is the culprit? any
help greatly appreciated!!
i'm using
dvgrab --format dv1 - \
| ffmpeg2theora -f dv -x 393 -y 288 --no-skeleton -o /dev/stdout - \
| oggfwd skylined.org 8000 pass /mountpoint.ogv
i tried different cameras and ffmpeg2theora 0.24 and (now) 0.27
dvgrab 3.5
ffmpeg2theora 0.24 and 0.27
oggfwd 0.2
icecast 2.3.2
ubuntu 10.4 with 2.6.32 generic-pae kernel.
--
sujet est machinique!
Nova deViator ¤ http://deviator.si ¤ http://skylined.org ¤
20 May
20 May
2:35 p.m.
Quoting Luka Prin?i? // Nova deViator <nova(a)deviator.si>si>:
The obvious guess would be that your CPU is too slow and can't keep up
with recoding the video stream.
The other guess is that the camera and/or the interface can't push
that amount of data in real time to the PC.
3:07 p.m.
New subject: skipping chunks of video with ffmpeg2theora and icecast, DVinput
On 05/20/2011 02:35 PM, Peder Hedlund wrote:
Hi Luka,
The problem is likely the former (the DV input is a bitstream with
constant bps and usually no problem): Panning and zooming puts
addidtional some strain on the encoder (motion compensation calc) and
also produces bandwidth spikes.
AT LAC, we were able to kick out some remote-participants with quick
camera panning due to bandwith spikes so we tried to avoid those :) BTW,
we were able to max-out CPU a 2.8GHz quad-core with two ffmpeg2theora
instances.
You can check if decreasing the quality (`-v 3`) helps and give
`--speedlevel 2` a try: it uses less CPU, for increased output bandwidth.
Down-scaling the video decreases CPU usage of the encoder, but requires
a few CPU cycles to perform the scaling, in particular if scaling to non
multiples of 16: try `-x 384 -y 288 -aspect 4:3` instead of
` -x 393 -y 288` (it /should/ not make a difference since Theora
requires the geometry to be multiples of 8 (or 16?), but ffmpeg2theora
may just be scaling/cropping/expanding twice?!).
HTH,
robin
4:41 p.m.
New subject: skipping chunks of video with ffmpeg2theora and icecast, DVinput
hija,!
well, i'm using 3G quadcore, and the CPU usage is quite low. i haven't
tested the spikes when doing more action and zooms.
Robin Gareus <robin(a)gareus.org>rg>:
good points. thanks.
i was especially eager to hear ideas from the experienced LAC team!
it is true we have very low upload bandwidth here (256k). we will
upgrade it in next few days to 768k. when i lowered resolution to
160x128 it seems to help quite a lot...
i will do more tests, but the conclusion seems to be that the zooms and
many actions creates bandwidth spikes and that causes skips between
encoder and server, correct?
l.
--
sujet est machinique!
Nova deViator ¤ http://deviator.si ¤ http://skylined.org ¤
22 May
22 May
12:57 a.m.
New subject: skipping chunks of video with ffmpeg2theora and icecast, DVinput
On 05/20/2011 04:41 PM, Luka Prinčič // Nova deViator wrote:
yes. since you mentioned you have a very powerful machine, try the
constant bitrate mode of ffmpeg2theora. it has a slight quality
trade-off and eats unspeakable amounts of cpu, but it will allow you to
go very near to the line limit without fear of network congestion.
best,
jörn
5078
days inactive
5079
days old
linux-audio-user@lists.linuxaudio.org
4 comments
4 participants
participants (4)
-
Jörn Nettingsmeier -
Luka Prinčič // Nova deViator -
Peder Hedlund -
Robin Gareus