Yes. MPEG-1 and MPEG-2 are not fully supported by QuickTime, which can only export the video from source data in these formats. This presented a challenge to ViddyUp!, which is based on QuickTime. We're pleased to say that by extracting the audio independently of QuickTime ViddyUp! does export both video and audio from most MPEG-1 and MPEG-2 sources.
Audio and video synchronization for these files, however, is hit or miss. During our research we experienced successful audio and video synchronization in over 80% of our test files. The remaining tests resulted in synchronization issues, unpredictably ranging from slight to very noticeable. We repeated our tests with several leading video conversion tools and their results ranged from somewhat less successful to slightly more successful than our own success rate. Essentially this means that an MPEG-1 or MPEG-2 file that you plan to convert may export with excellent audio and video synchronization, but there is really no guarantee.
Synchronization problems are well known to those experienced in re-encoding MPEG-1 and MPEG-2 source files. Video/audio stream discrepancies are normally handled transparently by the MPEG standard's advanced timing mechanisms. MPEG decoders can use timing information embedded in each video and audio sample to compensate for corruption and/or the disappearance of parts of the source data. But extracting the audio separately and adding it to another type of movie file, such as an MPEG-4 or H.264 file, removes any timing information from the audio stream. To reach perfect synchronization beyond this point, especially with less than ideal source material, the movie file's contents would have to be reviewed in a video editing application, stretching or scaling the audio and/or video to match key events in the video stream until synchronization is achieved.
Because of these considerations, we cannot make any assurances about the outcome of exported MPEG-1 and MPEG-2 file formats. We have made every possible effort to ensure compatibility within our limitations and believe we are on par with current consumer tools. If you experience synchronization problems that are not present in the source material, feel free to let us know.