Avisynth audio sync errors
 

Capturing using a SR-VS30U, a Pinnacle Moviebox USB-510, and Virtualdub. Finished AVI test looks pretty good (perhaps absent some color correction) and audio is in sync. Using an Avisynth script to encode, the finished file looks great, but the audio is not in sync for most of the 10 minutes (though it seems to sync toward the end and the duration is the same).

Script

SetFilterMTMode("QTGMC", 2)
FFmpegSource2("C:/Users/Allen/Videos/Captures\3.avi", atrack=1)
ConvertToYV12()
AssumeFPS("ntsc_video",sync_audio=true)
AssumeBFF()
QTGMC(Preset="Slower", FPSDivisor=2, Edithreads=4)
Crop(10,4,-10,-10)
Spline64Resize(1448,1080)
LimitedSharpenFaster(ss_x=1.9, ss_y=1.9, Smode=1, strength=60, radius=4, Lmode=1, wide=false, overshoot=1, soft=-1, edgemode=0, special=false, exborder=1)
AddBorders(236, 0, 236, 0, color_black)
Prefetch(threads=10)

Media Info for AVI:

Complete name	C:\Users\Allen\Videos\Captures\3.avi
Format	AVI
Format/Info	Audio Video Interleave
Format profile	OpenDML
File size	3.78 GiB
Duration	10 min 23 s
Overall bit rate	52.1 Mb/s
Writing library	VirtualDub build 32842/release
Video
ID	0
Format	Lagarith
Codec ID	LAGS
Duration	10 min 23 s
Bit rate	50.5 Mb/s
Width	720 pixels
Height	480 pixels
Display aspect ratio	3:2
Frame rate	29.970 (30000/1001) FPS
Standard	NTSC
Color space	YUV
Chroma subsampling	4:02:02
Bit depth	8 bits
Bits/(Pixel*Frame)	4.876
Stream size	3.66 GiB (97%)
Audio
ID	1
Format	PCM
Format settings	Little / Signed
Codec ID	1
Duration	10 min 23 s
Bit rate mode	Constant
Bit rate	1 536 kb/s
Channel(s)	2 channels
Sampling rate	48.0 kHz
Bit depth	16 bits
Stream size	114 MiB (3%)
Alignment	Aligned on interleaves
Interleave, duration	33 ms (1.00 video frame)
Interleave, preload duration	500 ms

Media Info for Output MP4

Format	MPEG-4
Format profile	Base Media
Codec ID	isom (isom/iso2/avc1/mp41)
File size	3.63 GiB
Duration	10 min 20 s
Overall bit rate	50.2 Mb/s
Writing application	Lavf58.46.101
Video
ID	1
Format	AVC
Format/Info	Advanced Video Codec
Format profile	High@L5
Format settings	CABAC / 4 Ref Frames
Format settings, CABAC	Yes
Format settings, Reference frames	4 frames
Codec ID	avc1
Codec ID/Info	Advanced Video Coding
Duration	10 min 20 s
Bit rate	50.0 Mb/s
Width	1 920 pixels
Height	1 080 pixels
Display aspect ratio	16
Frame rate mode	Constant
Frame rate	29.970 (30000/1001) FPS
Color space	YUV
Chroma subsampling	4
Bit depth	8 bits
Scan type	Progressive
Bits/(Pixel*Frame)	0.805
Stream size	3.62 GiB (100%)
Writing library	x264 core 160
Encoding settings	cabac=1 / ref=3 / deblock=1
Codec configuration box	avcC
Audio
ID	2
Format	AAC LC
Format/Info	Advanced Audio Codec Low Complexity
Codec ID	mp4a-40-2
Duration	10 min 20 s
Duration_LastFrame	-6 ms
Bit rate mode	Constant
Bit rate	128 kb/s
Channel(s)	2 channels
Channel layout	L R
Sampling rate	48.0 kHz
Frame rate	46.875 FPS (1024 SPF)
Compression mode	Lossy
Stream size	9.50 MiB (0%)
Default	Yes
Alternate group	1