Avisynth script encoding randomly stops

[ENunn]

i'm trying to encode one of my tape transfers via an avisynth script through ffmpeg. for some reason the process is stopping randomly in the middle of the encode with no error message. i loaded the script up in virtualdub and tried an encode, but i get this error after a while:


is there a fix? my source files are ffv1+flac. i'm running 64-bit avisynth+ 3.7.3 r4003

my script:

setmemorymax(65536)
v = lwlibavvideosource("g:\virtualdub\tape transfers\heat vs boston games 3 and 4 2012.mkv", fpsnum=30000,fpsden=1001)
a = lwlibavaudiosource("g:\recordings\heat vs boston games 3 and 4 2012.flac")
audiodub(v,a)
delayaudio(-.300)
assumetff().converttoyuv422(matrix="rec601", interlaced=true).convertbits(10)
Levels(95, 1,965, 0, 1020, coring=false,dither=true).tweak(bright=0, cont=1.00, hue=-0, sat=1.00, coring=false, dither=true).convertbits(8)
#turnRight().Histogram().TurnLeft()
Trim(263, 567113)
separatefields()
LSFplus(ss_x=1.5, ss_y=1.5, secure=false, Spwr=2, SdmpHi=0, soothe=false, keep=25)
FineDehalo(rx=2.5, ry=1.0)
neo_dfttest(sigma=105, tbsize=5)
weave()
f3kdb(dynamic_grain=true)
converttoyv12(matrix="rec601", interlaced=true)
prefetch(8)

ffmpeg commands i've tried:

ffmpeg -hwaccel auto -i "script.avs" -vf setfield=tff -c:v libx264 -x264opts tff=1 -x264-params opencl=true -crf 18 -b:v 0K -preset slow -aspect 652:480 -c:a libopus -b:a 192k -vbr on -compression_level 10 -frame_duration 60 -sample_fmt s16 -y  "output.mkv"

ffmpeg -i "script.avs" -c:v utvideo -c:a copy "output.avi"

i also tried a fast recompress to magicyuv in virtualdub, and i got the access violation error mentioned above.

[ProWo]

Maybe errors in the video or audiostream?

You could scan both streams with ffmpeg:

FFmpeg.exe -i "inputfile" -f null -

[ENunn]

Maybe errors in the video or audiostream?

You could scan both streams with ffmpeg:

FFmpeg.exe -i "inputfile" -f null -

no errors. my issue is happening at random. it could stop an hour in, 20 minutes in, 4 hours in, 2 hours in, etc. not sure why

[davexnet]

Maybe errors in the video or audiostream?

You could scan both streams with ffmpeg:

FFmpeg.exe -i "inputfile" -f null -

no errors. my issue is happening at random. it could stop an hour in, 20 minutes in, 4 hours in, 2 hours in, etc. not sure why

Perhaps some anomaly during multi thread.
Try lowering the Prefetch() to 2 and/or comment it out altogether

[ENunn]

Perhaps some anomaly during multi thread.
Try lowering the Prefetch() to 2 and/or comment it out altogether

trying that now. unfortunately that's probably gonna be a temporary solution, since my encoding speed is a lot slower now.

before that, i rebooted my pc and had another go at it, and i finally got an error message in ffmpeg.

[avisynth @ 000001ee95f73d40] LWLibavVideoSource: failed to make a frame
[in#0/avisynth @ 000001ee95f73ac0] Error during demuxing: Unknown error occurred

my lsmashworks is already up to date.

[ProWo]

Try to remux the mkv.

[ENunn]

Perhaps some anomaly during multi thread.
Try lowering the Prefetch() to 2 and/or comment it out altogether

didn't fix it.

Try to remux the mkv.

didn't help either.

i tried loading it with ffmpegsource2 and that didn't fix it either. i'm not sure what's causing it.

[johnmeyer]

Random stops when using Prefetch are pretty common. There are two things to try. First, try adding a SetMemoryMax(1024) command as the first statement. You can play around with how much memory to allocate.

The other thing is to change the Prefetch number. I always test my script before letting it run. Since I usual VirtualDub to run the scripts, I start a "Video Analysis Pass" and let it crank for 10-20 seconds. While this runs, I note the fps. Very often this will start out at one speed and either speed up or slow down. Note the reading after it has settled down. Then, repeat the test for a smaller Prefetch. You will find that the differences in fps are not at all linear, e.g., Prefecth(3) does NOT produce half the fps as Prefetch(6). In fact, sometimes it will get faster. Your goal is to find the sweet spot. The optimal point is also usually much more stable and should avoid your crashes.

[ENunn]

i tried changing the prefetch but it still didn't fix it. i transcoded to huffyuv and it seems to have worked. i don't know why, i've ran ffv1 files for ages and they all worked fine until now. not sure why.