AC3Filter cannot decode AAC audio from DVB-T stream/recording

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niczoom

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AC3Filter cannot decode AAC audio from DVB-T stream/recording

#1

Post by niczoom » Thu Dec 12, 2019 12:41 am

I have a HTPC setup with Win 10, WMC & a Hauppauge WinTV Quad tuner. I live in Australia and a short while back we had a new Channel '7Food Network' which broadcasts audio using AAC. At home I use AC3Filter to decode all my audio and route it either direct to the TV speakers or out through my AMP. Its worked great until this 1 channel started using AAC. AC3Filter has AAC listed as a codec it can decode but it doesnt work with this MPEG4 AAC audio stream from WMC, see below:

AC3Filter Decoder info:
Input format: MPEG Audio - 48000
User format: PCM16 Stereo 0
Output format: Unknown - 0

Filter chain:
(MPEG Audio - 48000) -> AudioDecoder -> (Unknown - 0)

AudioDecoder
(MPEG Audio - 48000) -> FrameSplitter -> (Unknown - 0)

FrameSplitter
No sync

Perhaps its a shortcoming of AC3Filter? LAV Filter decodes this stream ok, it shows as aac_latm.

Any ideas?
Last edited by niczoom on Thu Dec 12, 2019 5:10 am, edited 1 time in total.

niczoom

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#2

Post by niczoom » Thu Dec 12, 2019 4:15 am

... To add ...

I have all the LAV Filters & AC3Filter installed & have experimented with various setups. I also use the 'Codec Tweak Tool 6.4.5' which under 'Preferred decoders' has text in red font ... "These settings only apply to applications that use the preferred filter system of Windows .... such as WMP & WMC ..."

At the moment I have:

When playing the same .wtv video file in 'GraphStudioNext' & 'Windows Media Player' I get all 3 LAV icons (Splitter, Audio & Video) & the AC3Filter icon showing in the taskbar. The audio outputs great.

When using Windows Media Center I get only the LAV Video & AC3Filter icons showing, video plays but no sound.

Why in WMC am I getting no sound, I thought its internal player was WMP? Perhaps WMC can only use 1 audio decoder at a time and cannot 'chain?' them like above when both LAV Audio & AC3Filter are used.

jachin99

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#3

Post by jachin99 » Sun Dec 15, 2019 5:21 am

Maybe WMP is using 32 bit codec chains while WMC is using the 64 bit chain. It might be the same tool your using but try grabbing a copy of the preferred filter tweaker, open that, and see if you can set both 32 and 64 bit codecs. Just an idea, as it sounds like you have everything you need installed.

niczoom

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#4

Post by niczoom » Sat Dec 21, 2019 5:36 am

Using "Codec Tweak Tool : Win7DSFilterTweaker : Preferred decoders" I've made sure that both 32/64 bit selection were the same. I also set "Miscellaneous : Various Tweaks" Use 64bit WMP instead of the default 32bit version. Now, when playing the same .wtv file in WMP (now 64bit) it works as intended using all 3 LAV filters & AC3Filter the same as when using GraphStudioNext 64bit - Image showing the graph including LAV & AC3Filter https://ibb.co/CKH4fNZ.

Now, in "Codec Tweak Tool : Codec and Filter Management : Preferred splitters" I have all pertinent types set to 'LAV Splitter' (including .WTV .MPG .MPEG). I have disabled all Microsoft DTV-DVD Audio & Video decoders for both 32/64bit.

When I play the same .wtv file (with the AAC LATM audio) I only get LAV Audio & Video icons showing. LAV Splitter & AC3Filter are not being used.
  • Perhaps WMC is programmed internally to only use Microsofts own splitter?
  • Do you think because LAV Splitter is not being that causes AC3Filter to not open?
  • Also in WMC other video/audio types also do not use/open LAV Splitter either.

jachin99

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#5

Post by jachin99 » Sun Dec 22, 2019 4:08 am

Have you tried setting all wtv files back to Microsoft's decoder? I know for Live TV you will have a really hard time changing anything in the codec chain, which is something I just remembered. I think at one point others were able to use an old codec from PowerDVD 12 on 32 bit windows but not 64 bit windows. Try setting everything WTV to use MS decoders and see what happens as long as you know you can change it all back to the way that currently works for you. I don't think you need an extra splitter for WTV as I have only seen that referenced for mkv files. I always used MS decoders for live TV and I get AC3 just fine I believe but I get mpeg2 streams. You might also ask Hendrik (Author of LAV) if there is a known issue with his splitter and wtv files at the moment. http://forum.doom9.org/showthread.php?t=156191

niczoom

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#6

Post by niczoom » Sun Dec 22, 2019 5:17 am

Hi jachin99,

For me it was when 1 channel started using AAC audio, there was just no sound coming through my speakers. I then found out that AC3Filter cannot handle the type of AAC audio (AAC LATM) used in the DVB-T stream. LAV Audio can though, so I added it to decode all my audio to PCM. AC3Filter then post-processes the PCM audio that LAV was outputting (https://i.imgur.com/Cc7KyMW.png). As I mentioned before I got this setup and working with .wtv files using GraphStudioNext & WMP, I just assumed WMC would use the same codec chain with Recorded TV and/or Live TV, but no.

I use AC3Filter as my old amp cannot handle all the newer 5.1+ audio formats. So when I want to use my amp I run my Autohotkey script which changes my main audio over to optical output (direct to my amp) and silently run AC3Filter from the command line with a 'Preset' flag. AC3Filter's then ran with my 'amp' preset so my audio gets 'AC3 encoded' using a '3/0.1' Output Format, as I don't use rear speakers.

Have you tried setting all wtv files back to Microsoft's decoder? ... Try setting everything WTV to use MS decoders and see what happens
Not sure why? When I do this it just defaults back to standard MS, no LAV or AC3Filter involved.

I don't think you need an extra splitter for WTV as I have only seen that referenced for mkv files
Yes, I thought I read a similar post at some point regarding that as well. I've reverted back to the MS preferred splitter now which works fine. But I still don't get AC3Filter to kick it and work when using WMC as it does in GraphStudioNext and WMP.

So moving on from LAV Splitter. Any thoughts on how I can get AC3Filter to kick in and work when using WMC?

I've used Process Monitor (procmon.exe) to monitor ehshell.exe when playing live tv and recorded tv. I filtered out specific keywords hunting for registry entries read, I didn't notice much of interest.

jachin99

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#7

Post by jachin99 » Tue Dec 24, 2019 3:19 am

That's a tough one. Maybe WMC and wmp are different in terms of how they handle wtv files because ms didn't want users changing their live TV codecs? If that channel also broadcasts in stereo then maybe you could somehow listen that stream? Have you tried changing your speaker setup in WMC or windows to see how that effects things? Maybe your next best option is to try and listen to a different audio stream or downmix to stereo because you don't have rear speakers.

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#8

Post by jachin99 » Tue Dec 24, 2019 3:27 am

You might also look at ffdshow and see if you have any better luck with that but if wtv filters are locked in for live TV I'm not sure you will have any luck. I vaguely remember something about a change in win 8 where only mpeg 2 streams had the decoders locked in for live TV. I think I saw that in the manual for the preferred filter tweaker or on its site. You mentioned your stream is mpeg 4 so I thought I would bring it up

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