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TCM sound out of synch


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I have noticed in the last 24 hours that the sound on TCM HD is out of synch, made clear when anyone talks their dialog does not match their lips.  I am not seeing this on any other channel so it is pretty clear something is wrong at the source.  I have Comcast Cable in Richmond, Virginia.  Please fix this.  Thanks.

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I have noticed in the last 24 hours that the sound on TCM HD is out of synch, made clear when anyone talks their dialog does not match their lips.  I am not seeing this on any other channel so it is pretty clear something is wrong at the source.  I have Comcast Cable in Richmond, Virginia.  Please fix this.  Thanks.

Don't assume it's at the source. If it were then everybody's sound, on every cable and satellite system that carries TCM, would be out of sync and these boards would be swamped with complaints.

 

More likely it's at your cable company's end. They're either having a sync issue with the receiver they use to pick up TCM's signal off the satellite or somewhere between there and the point that they send it out to you. For that matter, it could very well be your own cable box and yes it could  just affect channel.

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Don't assume it's at the source. If it were then everybody's sound, on every cable and satellite system that carries TCM, would be out of sync and these boards would be swamped with complaints.

 

More likely it's at your cable company's end. They're either having a sync issue with the receiver they use to pick up TCM's signal off the satellite or somewhere between there and the point that they send it out to you. For that matter, it could very well be your own cable box and yes it could  just affect channel.

 

In the last couple years I went from TW digital cable to Directv, and the improvement in that regard was substantial.  Directv still has occasional synch issues (which may come from the provider or from the network), but gone are audio synch offsets that are one or two spoken words off.  Now at the worst it seems it is just fractions of a second off (~50ms-150ms at the absolute worst).

 

P.S. To the OP, I just checked, and Tension, Cause For Alarm, No Questions Asked, and The Racket all came in for me on Directv without any sync issues.  Were these off for you?

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I have noticed in the last 24 hours that the sound on TCM HD is out of synch, made clear when anyone talks their dialog does not match their lips.  I am not seeing this on any other channel so it is pretty clear something is wrong at the source.  I have Comcast Cable in Richmond, Virginia.  Please fix this.  Thanks.

At times I have noticed the same thing when I watch my TCM HD channel, it can get really distracting. But I can also watch TCM on the regular channel (picture is often somewhat darker). l don't know the technical answer to this.

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I have noticed in the last 24 hours that the sound on TCM HD is out of synch, made clear when anyone talks their dialog does not match their lips.  I am not seeing this on any other channel so it is pretty clear something is wrong at the source.  I have Comcast Cable in Richmond, Virginia.  Please fix this.  Thanks.

 

Just at about the point in which you posted, the audio on TCM dropped out completely in NYC on Time Warner Cable. It was out for 40 minutes but as I had gotten a copy of TOO LATE FOR TEARS, I was just grateful for that favor. I did call Time Warner and while on the phone with them, the audio returned.

 

About a year ago there were similar off-synch problems, really bad and getting progressively worse while I could not get Time Warner to admit that it was anything other than an equipment problem at my end. But I had two new boxes and the issue affected both of them. I came here to ask the board admins to get someone to intercede as this was affecting the largest cable company in the largest TV market. My concern was appreciated. The next time I called Time Warner, they had a taped message come on before offering the menu choices. The message said that if you're calling about the TCM audio problems, they are working on it.

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At times I have noticed the same thing when I watch my TCM HD channel, it can get really distracting. But I can also watch TCM on the regular channel (picture is often somewhat darker). l don't know the technical answer to this.

 

Unlike the way audio and video are always perfectly lined up on celluloid, digital audio and video are stored and transmitted separately from one another, are read at different times, and are then assembed just before you see it.

 

The audio and video are put into different frames from each other.  These separate frames are then encapsulated into packets and sent, just like the way the internet carries files from one point to another.  Except that in this case if a packet gets dropped or lost there is no error checking attempted and no effort to resend dropped packets at a later time.  They are needed in a contiguous stream that is close to operating in real time, so numbering them on one end, and then detecting/requesting/resending and reordering them correctly on the other end would not work very well. 

 

Consistency of the audio frames to video frames is absolutely essential for synchronization.  So if packets are dropped that contain audio frames or video frames that are relevent to surrounding packets, then syncronization offset errors start to build up, in a cumulative way.

 

That, and cable systems in the US still use the older MPEG2 standards, which were really developed for local storage and retrieval systems, such as DVD, not so much for maintaining A/V synch over long distances and multiple "hops" where packets are likely to get dropped. 

 

Blu-Ray, US satellite, and IPTV (Amazon, Netflix, etc) all use a more recent H.264 standard which is more neatly defined and overall better adapted for this.

 

There is no simple solution to this problem, or else everyone would have already adopted it.  Cable has a large amount of infrastructure to update, larger than anyone else, but updates including H.264 standards are already beginning to happen in some areas, based on what I have read.

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  • 2 weeks later...

Wednesday evening 7/29/2015 9:07PM PST-------------   I just advised Comcast  that ONLY TCM HD channel 789 audio is again out of sync with video.  Had to watch "Separate Tables"   on  standard def Comcast TCM channel 501 which is, and always is,  in sync.

 

The only reason I report these re-occurrences on message board is because I don't know if it is Comcast or TCM who resolves.  Comcast CSR said it could be at their end.  

 

Stephen L

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  • 1 month later...

Once again sound is out of synch on TCM HD here in Richmond, Virginia, via Comcast Cable.  Not sure where this can be remedied, but over the last four months I have seen it happen over and over again.  I cannot remember any other channel ever having this problem, only TCM HD.  Can something be done to fix this?  It essentially makes watching the channel impossible.

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