[MPlayer-users] SVCD from TV card

[rcooley]

On Mon, 22 Dec 2003 15:40:50 +0100
Torsten Römer <troemer at swipnet.se> wrote:

> I am trying to encode to SVCD from the TV card. It "almost" seems to 
> work, MPlayer and Xine can play the resulting SVCD (while MPlayer
> hangs a bit) but my DVD Player cannot play it at all (just hangs)

MPlayer is very flexible, it will play practically anything...  Hardware
players are almost always the exact opposite, and will only play if it
is exactly how it wants it.

> I encode like this:
> 
> mencoder -tv driver=v4l:width=480:height=576 tv://
>           -of mpeg
>           -ovc lavc
>           -oac lavc
>           -lavcopts 
> vcodec=mpeg2video:vbitrate=1500:aspect=4/3:acodec=mp2
>           -o test.mpg
> 
> Then I use vcdimager to create the SVCD. Something is strange here, it
> 
> warns me:
> 
> ++ WARN: mpeg stream will be padded on the fly -- hope that's ok for
> you!++ WARN: autopadding requires to insert additional 232944 zero
> bytes into MPEG stream (due to 844 unaligned packets of 845 total)
> ++ WARN: this VCD type should not contain MPEG1 streams
> 
> Regarding the packet alignment I have no idea how to solve it.

To solve it, you must re-write the MPEG container code for mplayer...

> I am also surprised about the warning that it's an MPEG1 stream, while

You wouldn't be if you read the docs...  -of mpeg is for mpeg1, not
mpeg2.

> Available output formats:
>    avi      - Microsoft Audio/Video Interleaved
>    mpeg     - MPEG-1 system stream format


> mplayer says:
> 
> VIDEO:  MPEG2  480x576  (aspect 2)  25,000 fps    0,0 kbps ( 0,0
> kbyte/s)

Yes, mplayer has no problem playing an MPEG2 video inside an MPEG1
container...  You won't be so lucky with other players.

> Does anybody have an idea why my DVD Player (and also MPlayer) don't 
> like the resulting SVCD?

Yes, your DVD player doesn't like it because it isn't really an MPEG2
stream.

> I created some SVCD's with transcode and mpeg2enc which works nice,
> but it's way too slow to encode from the TV card...

First of all, mpeg2enc isn't the only codec available with transcode. 
Using ffmpeg's mpeg2video codec for video will make things about 3X
faster.

Secondly, you could try ffmpeg...  It's supposed to be able to encode
straight from v4l.

Finally, the way you are currently doing it with mencoder is actually
just fine.  You simply need to dump the video and audio to seperate
files, and use a program like mplex or tcmplex to combine them into a
*real* mpeg2 container... It will play in your DVD player, and won't
need to be padded by vcdimager.  The downside is, it's entirely possible
that the video/audio will be out-of-sync.  

I can't really help with sync problems, since all my experience
has led me to one conclusion: Some encoders keep sync with some
videos, and some don't...  No video encoder on Unix, that I've
found (eg ffmpeg/ transcode/ mpeg2enc/ mencoder) will consistently
maintain sync when outputing audio/video to seperate files.

> 
> Thanks in advance
> Torsten