Bframe Decoder Lag Warning – Again

[grindlestone]

Bframe Decoder Lag Warning in VirtualDub

I'll try to be as clear as possible.

I've looked through the forums and I know what causes this. My question is this - is there a way to turn this warning off ?

I'm using sequences and scenes from existing Xvid compressed movies, cutting them into new short films (basically making music videos in Windows Movie Maker by combining bits of old documentaries with a new soundtrack). I am using with VirtualDub-MPEG2 to cut out the scenes I want to use. As I am sure some of you realise, when I cut sequences from these Xvid movies the "Bframe Decoder Lag" warning is included at the beginning of each one.

Now, I don't want the original soundrack – just the movie part, so synchronisation between original audio and the video is not an issue. I just want to copy bits of the video out into new files.

Is there a way to get rid of this warning so it doesn't appear in every sequence I cut it into my finished clip?

Alternatively, can someone point me to a better tool for clipping sequences out of an existing avi movie? (Though it must be said VirtualDub is great at this)

[celtic_druid]

The frame is just generated by the VFW decoder, it isn't actually there, you aren't actually adding to each clip when you cut. If you want to edit via VFW, my advice would be to encode with packed bistream enabled.

[grindlestone]

The warning appears on each clip I cut out and displays even when they are assembled inside Windows Movie Maker.

[Matthew]

In avisynth I just use
FreezeFrame(0,1,1)
to replace frame 0 with frame 1.

I don't think this necessarily fits into what you are doing, but what you can do (although I've never had the need to try it) is resave the whole avi (preferably using a lossless codec such as huffyuv), and then do your cutting. In this case you should only get the error message once, at the front of the resaved avi. Any subsequent cuts should be fine.

Lots of HD space is required is the downside.

[bond]

as celtic_druid pointed it out, there is no frame in the stream which says "decoder lag", its just caused by the vfw decoder (vfw gets used in virtualdub for example) as .avi and vfw isnt able to handle b-frames without workarounds like the decoder lag

if you for example play the stream in any directshow player (eg wmp) you dont get this decoder lag message (as directshow doesnt have the problems as vfw)

[grindlestone]

Thanks so much for all your replies. If as you say the message will not be visible in the finished movies then perhaps I have little to worry about. I will try re-encoding the whole source avi again never-the-less.

Thanks heaps eveyone

[Matthew]

Well, I was assuming windows movie maker re-encodes the avi. The error message will be hardcoded into each clip in the file output if that is the case. So how you proceed depends upon whether my assumption was correct :)

[grindlestone]

Update:

I ended up de-compressing the offending movies which solved the problem and had the benefit of making the cutting process far easier. I also changed over to Adobe Premiere Pro 1.5 to do the editing (it did not like the compressed clips anyway). Now all is going very well indeed.

Thanks