[mythtv-users] A/V delay when recording HD

[Geoffrey Schwartzreich]

I do think Comcast applies Dynamic-range compression on the audio of most
channels, or the feeds have it already.

TNTHD is awful about timecode problems. Sometimes it crashes my TiVo, and
files that I move from the TiVo and play back have numerous stream errors
and break VLC sometimes.

So, I think it's safe to say that Comcast or the upstream provider is
mucking around with the audio track or the timecoding is just overall
inaccurate on some feeds.

Geoff


On 10/7/08 4:52 PM, "Florin Andrei" <florin at andrei.myip.org> wrote:

> Brad Fuller wrote:
>> 
>> AFA your captured stream: I assume you captured a QAM256 stream from
>> the coax since you are using HDHR.
> 
> Well, forget the OP, explain my situation. :-)
> So yeah, it's a QAM256 (I *think* it's 256), recorded by MythTV from an
> HDHR tuner, from a regular Comcast cable feed. MPEG2 1080i. Upon
> analysis, the A and V tracks in the .mpg file turned out to be not
> aligned, there's an A/V timing difference slightly bigger than 1000ms.
> 
> MythTV and pretty much any player is aware of the difference and the
> file is played in sync. So it looks like the timing diff is done on
> purpose by some component of the recording chain, and the whole thing is
> done properly.
> 
> My question was - why are not A and V muxed in sync? Why there's a time
> delta at all? For some reason, I expected a file dumped from a broadcast
> feed to have A and V in sync, with a 0 ms difference in between.