ChrisDavis
31st January 2004, 18:18
I had a problem that I have since solved. While searching this forum for solutions I saw several others with the same problem. I thought I might post what I found just in case someone might benefit from it.
The Problem: I have a vacation DVD made by the Hotel we stayed at. It will not play in some DVD players but will play in others. I also wanted to re-author it to combine a second video from the same trip. Whenever I tried to bring the single VOB file into an authoring program it would import at 51 seconds long instead of the 16 minutes it actually was. Also it would occasionally freeze whatever authoring software I used. DVD Lab was the only authoring program that imported it at the correct length, but it was unable to demux the VOB and thus could not compile it.
What I found: DVD Lab reported that it had been sampled at 9900 kbs., a rate that was on the edge for American DVD Players. The Hotel had used 51 seconds of canned footage at the beginning and it appeared that they spliced VOB's to get it combined with the footage that they took of us. This left the header indicating that the VOB was only 51 seconds long. It appears that DVD players do not use this header, they use the information in the IFO file, which did indicate the correct length. When I looked at the packets with VOB Edit there was an "unknown" garbage packet at the 51 second point. When I tried to demux the VOB with VOB Edit the resulting MPG also had the 51 second header and also would not import properly into my authoring software.
The Solution: I used VOB Splitter to remove the header from the VOB file. I never did actually split the file, I just told VOB Split to extract the entire file, but remove the 4K header. It has a check box for remove or include 4K header. At that point I had a file that would import with the correct time length. The authoring software I like to use does not support VOB importing or AC3 audio, so I used VOB Edit to demux the headerless VOB and BeSweet to convert the AC3 audio to a wave file. I did notice that if I demuxed the audio prior to stripping the VOB's header that there was an audio sync error equal to 4K in file length. In other words the audio file came out minutely shorter in time than the video file. The difference in time length was equal to 4K of my audio sampling rate. So strip the header before demuxing audio and video. Also once I had the video in the authoring software it was simple enough to remove the bad frame at 51 seconds.
I hope this helps some one. Many of you experts probably knew this already, but I had to learn the hard way.
The Problem: I have a vacation DVD made by the Hotel we stayed at. It will not play in some DVD players but will play in others. I also wanted to re-author it to combine a second video from the same trip. Whenever I tried to bring the single VOB file into an authoring program it would import at 51 seconds long instead of the 16 minutes it actually was. Also it would occasionally freeze whatever authoring software I used. DVD Lab was the only authoring program that imported it at the correct length, but it was unable to demux the VOB and thus could not compile it.
What I found: DVD Lab reported that it had been sampled at 9900 kbs., a rate that was on the edge for American DVD Players. The Hotel had used 51 seconds of canned footage at the beginning and it appeared that they spliced VOB's to get it combined with the footage that they took of us. This left the header indicating that the VOB was only 51 seconds long. It appears that DVD players do not use this header, they use the information in the IFO file, which did indicate the correct length. When I looked at the packets with VOB Edit there was an "unknown" garbage packet at the 51 second point. When I tried to demux the VOB with VOB Edit the resulting MPG also had the 51 second header and also would not import properly into my authoring software.
The Solution: I used VOB Splitter to remove the header from the VOB file. I never did actually split the file, I just told VOB Split to extract the entire file, but remove the 4K header. It has a check box for remove or include 4K header. At that point I had a file that would import with the correct time length. The authoring software I like to use does not support VOB importing or AC3 audio, so I used VOB Edit to demux the headerless VOB and BeSweet to convert the AC3 audio to a wave file. I did notice that if I demuxed the audio prior to stripping the VOB's header that there was an audio sync error equal to 4K in file length. In other words the audio file came out minutely shorter in time than the video file. The difference in time length was equal to 4K of my audio sampling rate. So strip the header before demuxing audio and video. Also once I had the video in the authoring software it was simple enough to remove the bad frame at 51 seconds.
I hope this helps some one. Many of you experts probably knew this already, but I had to learn the hard way.