Sound crackling when playing AC3 through SPDIF on HTPC

RonDMC · 21st July 2009, 1:36 AM

As the title suggest I have been having this issue for a while where sound is crackling when playing 720p MKV files through SPDIF on my HTPC connected to my AMP. I have converted lots of my HD-DVD's to MKV and none of these have this issue, xvid, divx, other 720p MKV files are fine it just seems like 320kps 720p MKV's are an issue. It's not continually crackling just when there is lots of bass etc or certain words are said, I am using an A-bit Fatality F190 Mobo with onboard sound ( Realtek HD Audio) connected to Yamaha AMP. DTS plays fine also.

I have tried the following:

Updated Audio Drivers from Realtek
Disabled SPDIF Passthrough in FDDSHOW and the problem goes away but I only get 2.1 instead of 5.1 audio
Played with FDDShow settings and Realtek settings in control panel

I am stumped, I have a heap of 1080 and 720 MKV's encoded at different bitrates and no others seem to have the issue except these 720p AC3 files encoded at 320kbps if anyone has any suggestions it would be great.

cheers

RonDMC · 24th July 2009, 1:31 AM

No one has any ideas? Get a new sounds card, problem with FDDShow, something to do with AMP?

Maldark · 24th July 2009, 3:09 AM

If they're encoded at 320kbps that suggested they've been altered since the original master on the disc, most dvds are 448ish and blu-ray/HD are 640.

Now if they have been reencoded since beeing taken from the disc then if there was any kind of gain filter applied, or normalisation (ie. to make the softer parts louder) then what can typically happen is if something that's already outputting at maximum volume is then increased you end up with clipping, which can lead to very noticable popping. I've played with AC3 filter many times and if the gain's set too high then this is exactly what happens.

Just a suggestion, seems reasonable.

RonDMC · 24th July 2009, 11:44 AM

These were never on a disc, I didn't encode them. (I'm sure you can use your imagination) I can't see how it would be an issue with the encode becuase they are TV Shows and it does not just happen with one particular show it is all of them that are 720p 320kbps audio. I'm sure it has to be an issue on my end or other people would be complaining.

All the HD-DVD's that I have encoded to mvk I have obviously done so using the highest quality audio track and never had an issue.

Beaistheman · 24th July 2009, 4:26 PM

100% sure its ONLY with 5.1 and ONLY with the spdif??? if its only when using an optical cable, not coax, and it happens all the time when using it, but only in 5.1, then try changing the calbe. i Had this problem with my mates setup once, using an auzentech xfi prelude to a harmon kardon amp. It was the optical cable (damaged somehow) and was causing odd crackling and chirps sometimes, not all the time, and not at certain times, just randomly. Try it. It could be that simple

RonDMC · 27th July 2009, 12:12 AM

Yep only 5.1 with those encodes, tried another optical cable and another input on my AMP with no luck. Only other thing I can think of is a dedicated sound card but not sure if that will even fix it.

21st July 2009, 1:36 AM	#1
RonDMC Member Join Date: Jun 2005 Posts: 469	Sound crackling when playing AC3 through SPDIF on HTPC As the title suggest I have been having this issue for a while where sound is crackling when playing 720p MKV files through SPDIF on my HTPC connected to my AMP. I have converted lots of my HD-DVD's to MKV and none of these have this issue, xvid, divx, other 720p MKV files are fine it just seems like 320kps 720p MKV's are an issue. It's not continually crackling just when there is lots of bass etc or certain words are said, I am using an A-bit Fatality F190 Mobo with onboard sound ( Realtek HD Audio) connected to Yamaha AMP. DTS plays fine also. I have tried the following: Updated Audio Drivers from Realtek Disabled SPDIF Passthrough in FDDSHOW and the problem goes away but I only get 2.1 instead of 5.1 audio Played with FDDShow settings and Realtek settings in control panel I am stumped, I have a heap of 1080 and 720 MKV's encoded at different bitrates and no others seem to have the issue except these 720p AC3 files encoded at 320kbps if anyone has any suggestions it would be great. cheers

24th July 2009, 3:09 AM	#3
Maldark Member Join Date: Jul 2004 Location: Newcastle, NSW Posts: 578	If they're encoded at 320kbps that suggested they've been altered since the original master on the disc, most dvds are 448ish and blu-ray/HD are 640. Now if they have been reencoded since beeing taken from the disc then if there was any kind of gain filter applied, or normalisation (ie. to make the softer parts louder) then what can typically happen is if something that's already outputting at maximum volume is then increased you end up with clipping, which can lead to very noticable popping. I've played with AC3 filter many times and if the gain's set too high then this is exactly what happens. Just a suggestion, seems reasonable. __________________ Balthasar\|L3360@3.5GHz(8.5x412)\|4GB Patriot Viper DDRII1066 5-5-5-12\|UT-X48-T2R\|Gigabyte 4870\|Lian-Li PC65-B\|Seasonic M12D 850W\|2x320GB(RAID 0)+1.5TB Casper\|AMD 240\|4GB Corsair DDRII800 5-5-5-18\|GA-MA785GM-US2H\|Sapphire HD4550\|Antec NSK2480B\|640GB+2x2TB

24th July 2009, 1:31 AM	#2
RonDMC Member Join Date: Jun 2005 Posts: 469	No one has any ideas? Get a new sounds card, problem with FDDShow, something to do with AMP?

24th July 2009, 11:44 AM	#4
RonDMC Member Join Date: Jun 2005 Posts: 469	These were never on a disc, I didn't encode them. (I'm sure you can use your imagination) I can't see how it would be an issue with the encode becuase they are TV Shows and it does not just happen with one particular show it is all of them that are 720p 320kbps audio. I'm sure it has to be an issue on my end or other people would be complaining. All the HD-DVD's that I have encoded to mvk I have obviously done so using the highest quality audio track and never had an issue.

27th July 2009, 12:12 AM	#6
RonDMC Member Join Date: Jun 2005 Posts: 469	Yep only 5.1 with those encodes, tried another optical cable and another input on my AMP with no luck. Only other thing I can think of is a dedicated sound card but not sure if that will even fix it.