[FFmpeg-user] Sound or Video - but I can't get both to work...

Bradley D. Thornton Bradley at NorthTech.US
Mon Jun 13 03:54:47 CEST 2011


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I am having problems trying to screencast with audio.

I've got a pastebin with example output here:
http://pastebin.com/6D8zUxq8 and I've posted that link below too.

I've tried both cli (examples below) and recorditnow. When choosing
recordmydesktop in recorditnow, I get sound and video (but not very good
video).

I'm trying to do screencasts with audio and video, mostly of a single
xterm window, but some with apps on the desktop in X - no games though.

On the cli, with ffmpeg, I either get good sound, or good video, but not
both together :(

Everything dexcribed below is using ffmpeg on the cli only (which I have
come to prefer during this debugging process:

I get sound when I do this:

ffmpeg -f alsa -i plughw:0 alsaout.wav
(does not work with just hw:0 though)

I get video but no sound when I do this:

ffmpeg -f alsa -i plughw:0,0 -f x11grab -r 25 -s 1440x900 -i :0.0
- -acodec pcm_s16le -vcodec huffyuv -sameq screencast.avi

or this:

ffmpeg -f alsa -ac 2 -i plughw:0,0 -f x11grab -r 25 -s 1440x900 -i :0.0
- -acodec pcm_s16le -vcodec libx264 -vpre lossless_ultrafast -threads 0
output.mkv

- -f oss (gives an error - no device) and I do not have pulse.

There is no hw:0,1 hw:0,2 or plughw:0,1 plughw:0,2 - just 0 or 0,0 works
in the command line, but no sound when I do video.

I get various errors like:

[alsa @ 0x63a4f0]ALSA buffer xrun.

but all with "alsa buffer xrun." when i try video and sound.

I found: http://www.alsa-project.org/main/index.php/XRUN_Debug

but got this:

# echo 1 > /proc/asound/card0/pcm0p/xrun_debug
- -bash: /proc/asound/card0/pcm0p/xrun_debug: No such file or directory

So I looked:

# ls /proc/asound
NVidia@  card0/  cards  devices  hwdep  modules  oss/  pcm  seq/  timers
 version
# ls /proc/asound/card0
codec#0  id  oss_mixer  pcm0c/  pcm0p/  pcm1p/
# ls /proc/asound/card0/pcm0p
info  oss  sub0/
# ls /proc/asound/card0/pcm0p/info
/proc/asound/card0/pcm0p/info
# cat /proc/asound/card0/pcm0p/info
card: 0
device: 0
subdevice: 0
stream: PLAYBACK
id: CONEXANT Analog
name: CONEXANT Analog
subname: subdevice #0
class: 0
subclass: 0
subdevices_count: 1
subdevices_avail: 0

NVidia@ is a symlink to card0. I have an HP DV9000 laptop w/2GB RAM. I
am running KDE on Slackware64 13.1.

I want to screencast, mostly things I do in the xterm, but also my
desktop apps - no games, just tutorial like stuff.

Can you help me to figure out how I can make my screencasts work?

Thank you so much in advance if you can :)

I've got a pastebin with example output here: http://pastebin.com/6D8zUxq8

So far I haven't had much success in chan #ffmpeg on freenode, but I'm
still there, being hopeful, but perhaps it's time to bring this to the
more comprehensive community - besides, once I get this working I'm
going to want to see everyone elses tips and tweaks too :)




- -- 
Bradley D. Thornton
Manager Network Services
NorthTech Computer
TEL: +1.760.666.2703  (US)
TEL: +44.203.318.2755 (UK)
http://NorthTech.US

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