broken b frames

[PandoraZboX]

Hi, I have a few avi files made with the xvid codec, that keep giving me nasty blocks thoughtout the file. When I open them in virtualdub it says there is a broken b-frame (displayed on top of the picture while scanning through it).

I have installed the new xvid build hoping that would fix it, but it hasnt. I seem to get these blocks when decoding with both xvid and ffdshow.

Any ideas?

[lordadmira]

The codec itself writes that in the frame when the B-frame is corrupted. There's no way to fix it that I know of. What u can do is delete that frame from the stream and resave it.

LA

[PandoraZboX]

No, that isnt written on there except in virtual dub, and in virtualdub the blocks arent there, just the writing.

[lordadmira]

No u heard right. The codec writes "Broken B-frame" in the frame when the video is being decoded through the Video for Windows interface which is what Virtual Dub uses. Virtual Dub itself isn't writing that. When u play the file normally with ffDShow that isn't written there because Xvid isn't decoding it. The block garbage ur seeing is because the file is corrupted. Either during download or from harddrive corruption.

LA

[sysKin]

What to heck happened to good advice on our forum... ;)

If you see a message "broken b-frame, missing ref frame" in vdub, that means that the stream was cut from a bigger file and the file was not encoded with "closed GOV". The b-frame would normally be displayed in the previews scene, before the cut point.
There is no way to get rid of it. I'm always telling people to keep "closed gov" enabled, that lets you cut cleanly.
Directshow decoder does not display the "broken" message, it just decodes next frame. VfW decoder cannot decode next frame, so you see the message.

As for b-frames that are not displayed right: what's your decoder? Are they also not displayed right in vdub (don't count the "broken" one).

Radek