>Thank you for the contribution. You might be interested to read this > old report I did testing a/v sync of the DVEO SDI consumer, drivers, > and hardware: > http://www.mltframework.org/bin/view/MLT/LinsysSyncTest
Interesting. It is pretty much the same concept as the blip flash. But your method allows a visual comparison. It reminds me of how I have tested lipsync using an oscilloscope. You can run analog audio and video into a scope and trigger on the blip. Then you can use the scope to measure the offset to the video flash. > The challenge now is to figure out if the problems lie more in the > avformat consumer or producer, or at least how to isolate one to fine > tune it. Do you have any thoughts about that? At least with raw DV > output, we can check it with the dvthumbs.c I used in that study. If I were going to attack it, I would probably try to build a large test data set and then look for trends. For example, maybe a particular codec or container is always off by some fraction of one frame. Also, we could create a blipflash clip and feed it into ffmpeg directly - bypassing MLT altogether. Matroska seemed to do pretty good. It would be frustrating to focus on MLT only to find out the problem is in libav. > Also, how did you come up with the 3ms number? Why is 33ms - one frame > at 30 Hz - not acceptable? 33ms is well below the threshold for human perception. So from that perspective, 33ms isn't bad. But if you have a workflow that includes multiple decode/encode cycles, the offset could stack up into a problem. Let me rephrase what I was trying to say: If the offset is better than +/-3ms, then you can probably attribute that to rounding errors in the demux, decode, encode, mux and detection steps of the process. It may not be worth chasing. If the offset is worse than +/-3ms, then that probably indicates a programming error (not working as intended) and it may be worth trying to fix. Whether it is good or bad depends on your use case. ~BM ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Mlt-devel mailing list Mlt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mlt-devel
