Avisynth Script audio problem

[Mr_Flintstone]

Hey guys, I was hoping to get some help on an issue I have. I have a TS file I recorded a while back at 1080i with 5.1 Dolby audio (I double checked this in a couple different programs). I ran it through an Avisynth script

video="input.ts"
DirectShowSource(video, fps=29.97, convertfps=true)
Load_Stdcall_plugin("I:\yadif17\yadif.dll")
Yadif(Mode=1)
SelectEven()
TDecimate()

which gives me 23.976 fps video and matching audio. The only problem is that my audio is stereo when output to my editing software. Is there any way to push my 5.1 audio through Avisynth instead of stereo?

[poisondeathray]

DirectShowSource() is dependent on your directshow configuration . You probably have a stereo downmix somewhere configured. Fix your decoder (e.g if it's lav or ffdshow, make sure the audio configuration isn't set to stereo)

If you add

Info()

To the script, preview in vdub or avspmod, does it report stereo ? If it's 6ch , then however you got from avs script to your editing software is the problem, make sure you don't have stereo downmix there



Alternatively you can load the audio separately, or with different source filter

video="input.ts"
Load_Stdcall_plugin("I:\yadif17\yadif.dll")
DirectShowSource(video, fps=29.97, convertfps=true, audio=false)
Yadif(Mode=1)
SelectEven()
TDecimate()
vid=last

aud=FFAudioSource(video)

AudioDub(vid,aud)

This requires ffms2 (external plugin , not native with avisynth install)
https://code.google.com/p/ffmpegsource/

[jagabo]

Why don't you just keep the original 5.1 (AC3?) audio. Mux it into your final file.

[poisondeathray]

Also, for that script you can use Yadif(mode=0, order=1) and remove SelectEven() . Chances are it should be order=1, because almost all HD content is TFF

And are you sure this source should be deinterlaced, not field matched ?

Why don't you just keep the original 5.1 (AC3?) audio. Mux it into your final file.

That's a better idea

[Mr_Flintstone]

Why don't you just keep the original 5.1 (AC3?) audio. Mux it into your final file.

I tried that, and when I mux back together I get audio sync issues. When it goes through Avisynth, the audio is in sync, but stereo.

I tried the ffms2 plugin, and I get an error in FFMPEG and VirtualDub saying

Audio format change detected. This is currently unsupported. Channels: 2 --> 6; sample rate 48000; sample format unknown --> unknown
(I: TS Files\input.avs, line 8

video="Battle Los Angeles.ts"
DirectShowSource(video, fps=29.97, convertfps=true)
Load_Stdcall_plugin("I:\yadif17\yadif.dll")
Yadif(Mode=1)
SelectEven()
TDecimate()

aud=FFAudioSource("Battle Los Angeles.ts")

AudioDub(video,aud)

[jagabo]

I don't think VirtualDub can handle six channel audio.

<edit>
Looks like I was wrong. I just tested it and it worked.
</edit>

[Mr_Flintstone]

I'll tinker some, and see what I can come up with.

[jagabo]

By the way, in what way was the audio sync wrong when you muxed the original AC3 audio with the new video? If it was just shifted earlier or later you can fix that in the muxer by adding a delay (negative delay = advance).

[Mr_Flintstone]

OK, I guess I solved one problem. I decided to start from scratch and re-create my avs file. I typed it in exactly like my first one and saved it. When I opened it and tried to convert, it worked perfectly...??? I guess I typed something a little wrong in the first one.

[Mr_Flintstone]

By the way, in what way was the audio sync wrong when you muxed the original AC3 audio with the new video? If it was just shifted earlier or later you can fix that in the muxer by adding a delay (negative delay = advance).

The audio was slightly ahead of the video. It didn't get progressively worse, just off a bit. How, and where, should I add a delay?

[jagabo]

The audio was slightly ahead of the video. It didn't get progressively worse, just off a bit. How, and where, should I add a delay?

What container is your final product? A lot of muxers have an audio delay option. I usually use MMG (part of MkvToolnix) to make MKV files. You can use VirtualDub to mux AVI files. MMG example:

[Mr_Flintstone]

What container is your final product? A lot of muxers have an audio delay option. I usually use MMG (part of MkvToolnix) to make MKV files. You can use VirtualDub to mux AVI files. MMG example:

Sorry, I guess I should have said what I intended to do. I had been converting to DVD MPEG2 with FFMPEG, demuxing and burning DVDs with GUI4DVDAUTHOR. I've since found that HCENC gives better results producing M2V files. I was hoping to use that and the original AC3 audio (that was giving me the audio sync issue) and burn a DVD.

[jagabo]

ffmpeg can add an audio delay when encoding or muxing:
http://howto-pages.org/ffmpeg/#delay