Puppy Linux Discussion Forum

tommckellips · Joined: 31 Oct 2005 Posts: 32

Has anyone got some good advice on getting video capture working. I have been through VLC ffmpeg, mplayer with no sucess. I can play local files and even stream them out on the network but I can not get anything to grab video from my capture device I am trying to get video from the composite port.. Anyone know what I am messing up?
[img] http://www.geocities.com/tommckellips/pics/IMG_0002.png [/img]
[img] http://www.geocities.com/tommckellips/pics/IMG_0003.png [/img]

linuxcbon · Joined: 09 Aug 2007 Posts: 367 Location: here

did you try "cat /dev/video" ?

tommckellips · Joined: 31 Oct 2005 Posts: 32

Did that and got an endless stream of stuff.

linuxcbon · Joined: 09 Aug 2007 Posts: 367 Location: here

It means it works Very Happy

Try cat /dev/video > test.avi
Wait for 10 seconds and type CTRL+C to finish capture
Open test.avi with xine.

tommckellips · Joined: 31 Oct 2005 Posts: 32

Tried that and it gives me the engine failed to start - no demuxer found stream format not recognized.

linuxcbon · Joined: 09 Aug 2007 Posts: 367 Location: here

Try other players like vlc to open that video, or rename it to test.mpg ...

tommckellips · Joined: 31 Oct 2005 Posts: 32

I have VLC and had no luck with it at all, also mplayer no luck either, I do not see in it where to start a capture. This may help I have been trying different formats with ffmpeg with no good results yet, other than some actually create a file while others do not. I also get responses on cat /dev/video and cat /dev/video0
Here is a screen capture:
# ffmpeg -f video4linux -i /dev/video0 /root/testing.avi
FFmpeg version SVN-r7400, Copyright (c) 2000-2006 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --mandir=/usr/man --disable-bug --enable-mp3lame --enable-a52 --enable-gpl --enable-shared --enable-pp --eble-amr_nb --enable-amr_nb-fixed --enable-amr_wb --enable-pthreads --enable-dt--enable-faac --enable-faad --enable-libogg --disable-audio-beos
libavutil version: 49.1.0
libavcodec version: 51.28.0
libavformat version: 51.7.0
built on Apr 3 2007 14:43:22, gcc: 3.4.4
[video4linux @ 0xb7f102a0]Bad capture size (0x0) or wrong time base (25)
/dev/video0: Error while opening file
# ffmpeg -f yuv4mpegpipe -i /dev/video0 /root/testing.avi
FFmpeg version SVN-r7400, Copyright (c) 2000-2006 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --mandir=/usr/man --disable-bug --enable-mp3lame --enable-a52 --enable-gpl --enable-shared --enable-pp --eble-amr_nb --enable-amr_nb-fixed --enable-amr_wb --enable-pthreads --enable-dt--enable-faac --enable-faad --enable-libogg --disable-audio-beos
libavutil version: 49.1.0
libavcodec version: 51.28.0
libavformat version: 51.7.0
built on Apr 3 2007 14:43:22, gcc: 3.4.4
/dev/video0: Error while opening file
# ffmpeg -f yuv4mpegpipe -i /dev/video /root/testing.avi
FFmpeg version SVN-r7400, Copyright (c) 2000-2006 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --mandir=/usr/man --disable-bug --enable-mp3lame --enable-a52 --enable-gpl --enable-shared --enable-pp --eble-amr_nb --enable-amr_nb-fixed --enable-amr_wb --enable-pthreads --enable-dt--enable-faac --enable-faad --enable-libogg --disable-audio-beos
libavutil version: 49.1.0
libavcodec version: 51.28.0
libavformat version: 51.7.0
built on Apr 3 2007 14:43:22, gcc: 3.4.4
/dev/video: Error while opening file
# ffmpeg -f video4linux -i /dev/video0 /root/testing.mpg
FFmpeg version SVN-r7400, Copyright (c) 2000-2006 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --mandir=/usr/man --disable-bug --enable-mp3lame --enable-a52 --enable-gpl --enable-shared --enable-pp --eble-amr_nb --enable-amr_nb-fixed --enable-amr_wb --enable-pthreads --enable-dt--enable-faac --enable-faad --enable-libogg --disable-audio-beos
libavutil version: 49.1.0
libavcodec version: 51.28.0
libavformat version: 51.7.0
built on Apr 3 2007 14:43:22, gcc: 3.4.4
[video4linux @ 0xb7eef2a0]Bad capture size (0x0) or wrong time base (25)
/dev/video0: Error while opening file
#
THis folowing one acts like it is doing something, but never creates a file.
# ffmpeg -f mpeg -i /dev/video /root/testing.mpg
FFmpeg version SVN-r7400, Copyright (c) 2000-2006 Fabrice Bellard, et al.
configuration: --prefix=/usr --libdir=/usr/lib --mandir=/usr/man --disable-debug --enable-mp3lame --enable-a52 --enable-gpl --enable-shared --enable-pp --enable-amr_nb --enable-amr_nb-fixed --enable-amr_wb --enable-pthreads --enable-dts --enable-faac --enable-faad --enable-libogg --disable-audio-beos
libavutil version: 49.1.0
libavcodec version: 51.28.0
libavformat version: 51.7.0
built on Apr 3 2007 14:43:22, gcc: 3.4.4

This one has really stumped me.

tommckellips · Joined: 31 Oct 2005 Posts: 32

Ok 30 some odd hours later I got it to work. This site (which I just found) is a wealth of information. http://www.linuxtv.org/v4lwiki/index.php/TV_Recording
THe magic line to make my video capture work is :

ffmpeg -async 12 -vd /dev/video -ad /dev/dsp -f avi -r 25 -s 720x576 -croptop 8 -cropbottom 8 -cropleft 8 \
-cropright 8 -sameq -aspect 4:3 -acodec mp2 -ac 2 -ab 224k -ar 48000 -y -t 04:30:00 outfile.avi

The only problem is now I have no audio. This is a new issue to resolve since my sound card does work. Cat /dev/dsp does bring up a lot of stuff so I know that part is working. I'll start simple and check my feeds from the stereo and go from there. I'll post my findings or any more questions I have.
I am sure this can be made more to my needs but at least this made it work. Thanks for your help, your comments did point me in the right direction.

jamesbond · Joined: 26 Feb 2007 Posts: 297 Location: Chatswood, NSW

Congrats on your TV capture finally working. I didn't know ffmpeg can do capture - wow !

As for audio - I would like to share something that hopefully can help to point you to the right direction. I have a PCMCIA TV card and had a hard time got it working with tvtime, but finally it did. But no sound - same problem as yours.

After further reading, I found out that my tv card drivers does not directly channel its sound through /dev/dsp. In fact, it creates a new ALSA device (listed /proc/asound/cards) that provides sound capture. So, for my case, to be able to hear sound, I need to do sound-capture from my tv card's alsa sound dev, and straight away play it back to my actual m/b soundcard. This did the trick:

linuxcbon · Joined: 09 Aug 2007 Posts: 367 Location: here

Of course ffmpeg can record videos !
It can also convert any sound and video formats !

jamesbond · Joined: 26 Feb 2007 Posts: 297 Location: Chatswood, NSW

Thanks linuxcbon. Can ffmpeg capture straight from alsa (rather than oss) ?

linuxcbon · Joined: 09 Aug 2007 Posts: 367 Location: here

when you type ffmpeg , it shows all the options. Smile

-f option means "force format".

You can try

tommckellips · Joined: 31 Oct 2005 Posts: 32

I Figured out why my sound did not work. /dev/dsp appears to be pointed at my mic in and not my line in. I switched the stereos audio output to my PC's mic input and now I get audio and video capture. I also found I have to capture at 352x288 if I do anything larger my sound and video loose sync. This is on a Dell with a PIII 733 and 256 meg RAM.
Now my big problem is how do I compress the video capture on the fly, I my capture creates an avi but 48 minutes of video creates a avi file that is over 1.5 gig. It looks like it is supposed to be able to compress the video but I have not been able to make that work yet.

tommckellips · Joined: 31 Oct 2005 Posts: 32

Now that I have spent another day trying to learn the ins and outs of ffmpeg I have another question. How do I force it to use the line in side of my audiocard? It picks up fine off the mic side but the audio quality is not as good as the line in side if I could get part to work. Line in does work in other applications so I am assuming this is something that needs set in ffmpeg.

tempestuous · Joined: 10 Jun 2005 Posts: 3651 Location: Australia

I see a major shortcoming in your instructions so far: no video compression specified. This will result in very large uncompressed video files, but more importantly, will require a high datarate (possibly 25MB per sec) and your hard drive won't keep up.

Here's how to encode using MPEG2 video compression, with MP2 audio compression.