I have a few questions regarding how FF cards acheive correct A/V sync during live tv. I know there have been discussions about this in the past, but it seems they never ended up going anywhere... Please excuse my ignorance with any or all of this... It appears that under certain circumstances [NTSC content? or perhaps provider specific?], there is an A/V SYNC problem with playback [not live tv] of a decrypted stream [using my CI module, utilizing the CAM interface layer]...all FTA channels have perfect A/V SYNC. This ONLY happens on FULL FEATURED cards, like my NEXUS-S. With my NOVA-S, I do not experience the same problems. After some investigation, I have found that the SOFTWARE front ends keep A/V sync by using the AUDIO PTS as the master, and adjusting the VIDEO FRAMERATE to keep sync. The only possibility I can think of is that perhaps during the decryption process, the framerate of the video stream becomes variable...thus requiring SYNC to be kept by the method mentioned above [adjusting framerate based on AUDIO PTS]. Since FF cards use their own muxer, I was thinking perhaps this muxer uses some OTHER method to keep sync... The only way THAT could be possible is if the ECD chip is passing information along to the muxer, which doesn't happen at all when playing back a recorded stream....since you've already recorded the incorrect framerate, and there is no ECD activity during playback [since decryption was already acheived during initial recording] Questions: 1. What method does the FF muxer use to ensure proper A/V SYNC? 2. Can the FF muxer be modified at all? Perhaps, through patching the firmware? 3. Is this a valid assumption: The ECD chip provides SYNC info to the muxer for decrypted streams during LIVE TV I know that my questions are based on a series of assumptions that could possibly be completely incorrect, so I apologize if that is the case. Thanks, whoMAN
