I took most of my batch file from Andrew's suggestions from this thread.



I'm currently using to encode MPEG2 (720x480) --> xvid (512x384) on win32 using MPlayer-mingw32-dev-CVS-050928.

Firstly, there are several questions I have for people who know:

1. Am I missing any options?
2. How can I alter this to be a 3 or 4 pass encode?

Secondly, when I use that script I do get a file out that plays under Windows (mplayerc) just fine; however, one problem is that the resulting file has problems in virtual dub and virtualdub mod giving an error, "Warning: nothing to output bframe decoder lag."

Also, if I demux the mp3 file and analyze it with mrquestionman or encspot, I don't see the correct results. Mrquestionman usually shows the switches one used to encode (in this case --alt-preset fast standard). Additionally, the vbrheader is all messed up. The bitrates usually jump between 128,224,256 etc. in normal files. The demuxed file just hovers around 190 jumping by 1 kbps or so.

Can anyone suggestion what I'm doing wrong?

_________________
Retired KM user (R4 - R6.04); friend to LH users.

This assumes mencoder is in the local directory or at least accessible by the PATH variable.

I have heard of 3 pass Xvid transcoding but don't know anything about it. I suggest a quick google search.

From what I understand the 2 pass Xvid is the best the codec is capable of in terms of quality vs. bitrate. I found it dramatically better than single pass Xvid transcoding. I believe (I don't know for a fact but I have read it someplace) that MythTV only uses single pass transcoding.

Would anyone tell me how MythTV starts its transcoding jobs (via a script or embedded command or ??)? I'd like to modify MythTV to allow 2 pass Xvid transcoding if that is possible.

I did some experimenting with the H.264 x264 codec as well but the results were disappointing. I posted a thread in HOWTO on it. There has been lots of activity on the x264 codec recently so maybe it has improved. The last time I checked though it did not support interlaced video (which makes it unsuitable for normal NTSC recordings, I think) and it only supported mod16 resolutions (which makes it not capable of transcoding HDTV (1920x1080).

Best of luck with your camcorder conversions!

Andrew Lynch

Very cool... that's what I've been doing. Do your transcodes suffer from the problem I described in the 2nd part of my post also? They aren't valid avi files if VD can't edit them.

_________________
Retired KM user (R4 - R6.04); friend to LH users.

I do not use VirtualDub as I use Avidemux2 instead. I haven't had any troubles like you describe. However, I do occasionally get a transcode that has noticable AV sync problems. I have never figured out why but a new recording fixes the problem.

One wierd thing is that I have to load the mpg using AviDemux2 and then save it under a new name. Then it is a normal AVI file without any weirdness.

http://fixounet.free.fr/avidemux/

You might look into loading the dsmyth drivers as they may be smoothing over any inconsistencies with Windows drivers...

http://dsmyth.sf.net

Andrew Lynch[url][/url]

Thanks... I'm glad enough to now know how to capture from my camcorder. I'll check out those appls you mentioned, but for now I think I'll stick to the manual process I've been doing for xvid transcoding.... at least until I can sort out these things with mencoder.

_________________
Retired KM user (R4 - R6.04); friend to LH users.

Can you demux the mp3 stream from one of your encodes and then analyze it with mrquestionman (http://www.burrrn.net/?page_id=6). Let me know if it displays for the "encoder info" section. If you're using --alt-preset medium like your batch file, that should be reflected there. Also, if you play the demuxed file in winamp and watch the bitrate field, it should only jump around by the standrd cbr values, i.e. 128, 160, 192, 224, 256, 320. If it moves around in regular whole number steps, like 190, 192, 187 for example, the mp3 is written with some invalid settings.

_________________
Retired KM user (R4 - R6.04); friend to LH users.

Please let me update the above. x264 still does not support interlacing however I am working to build (with some help) a script that uses mencoder to deinterlace the video prior to feeding it to the x264 codec for encoding. In other words, a clunky workaround to this limitation.

Apparently, the developers of x264 are steadily working towards an implementation that supports interlacing but that it is a ways off (several months apparently). Hopefully the mencoder based script gives decent results (test transcode is underway now and I will post later as an update to the HOWTO thread on H.264)

In addition, x264 just recently posted a change to their svn that allows non-mod16 resolutions to be encoded. Now x264 supports HD mode (1920x1080) and a whole bunch of other new neato features. I have some other stuff to do first but I will be rebuilding my Mplayer/Mencoder with x264 fairly soon to get the new features.

Thanks!

Andrew Lynch