[Critical Bug] The output video contains only static image with audio — fails silently

[zakimimit]

Problem Description

[Critical Bug] The output video contains only static image with audio — fails silently

After encoding, the output file plays as a static (frozen) image with audio only — no actual video motion is visible. The log reveals the root cause: the audio sync engine detects continuous backwards PTS timestamps throughout the entire encode, causing it to aggressively drop video frames. Only 21 video frames were muxed out of 22,855 expected, resulting in a near-static output.

Elapsed encode time: ~2 seconds (abnormally fast — confirms almost no video was encoded)

Expected Behavior

• The output MKV should contain a fully encoded video stream with smooth playback matching the source duration and framerate (~25 fps).

Actual Behavior

• Output video is a static image — only the first frame is visible for the entire duration.
• Audio plays back normally.
• The encode completes in ~2 seconds (abnormally fast).
• Log shows continuous audio PTS regression from the very start of encoding

sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 14836021 sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 15921781 ... (repeats hundreds of times across entire file duration)

• Final mux stats confirm near-total video frame loss:

sync: got 26 frames, 22855 expected vfr: 21 frames output, 5 dropped and 0 duped for CFR/PFR mux: track 0, 21 frames, 40966 bytes, 0.43 kbps ← video mux: track 1, 38231 frames, 5473480 bytes, 57.27 kbps ← audio

What version of VidCoder are you running?

12.19 VelopackInstaller

Encode Log

HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 14836021
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 15198660
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 15921781
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 16639621
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 17363221
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 18086821
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 18810871
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 19534471
HB [21:32:02] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 19897110
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 20263831
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 20620710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 21349231
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 22067071
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 22790671
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 23158710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 23876071
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 24599671
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 25323271
HB [21:32:02] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 25685910
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 26046871
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 26765071
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 27127710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 27855871
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 28579471
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 29297671
HB [21:32:02] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 29660310
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 30021271
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 30383910
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 31106671
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 31830271
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 32553871
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 32916510
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 33639271
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 34362871
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 35086831
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 35810431
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 36172710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 36890071
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 37613671
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 38337271
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 39060871
HB [21:32:02] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 39423510
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 39784471
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 40508431
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 40870710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 41593471
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 42317071
HB [21:32:02] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 42679710
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 43402471
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 44126071
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 44844271
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 45567871
HB [21:32:02] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 46286071
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 47009671
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 47372310
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 47733271
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 48095910
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 48813361
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 49175161
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 49537800
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 50260561
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 50984161
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 51346800
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 51708600
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 52070400
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 52793161
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 53517121
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 54240721
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 54958561
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 55321200
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 55683000
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 56044800
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 56767561
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 57491161
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 58209361
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 58577400
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 58932601
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 59295600
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 59662800
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 60024600
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 60741961
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 61471321
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 61833600
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 62556361
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 63279961
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 64003921
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 64366200
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 64727161
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 65089800
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 65812561
HB [21:32:03] sync: audio 0x1 time went backwards 21 ms, dropped 1 frames. PTS 66180600
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 66541561
HB [21:32:03] sync: audio 0x1 time went backwards 42 ms, dropped 2 frames. PTS 66904200
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 67621561
HB [21:32:03] sync: audio 0x1 time went backwards 64 ms, dropped 3 frames. PTS 68345161
HB [21:32:03] reader: done. 1 scr changes
HB [21:32:03] sync: first pts video is 68706000
HB [21:32:03] sync: "Chapter 1" (1) at frame 1 time 68706000
HB [21:32:03] work: average encoding speed for job is 0.000000 fps
HB [21:32:03] vfr: 21 frames output, 5 dropped and 0 duped for CFR/PFR
HB [21:32:03] vfr: lost time: 0 (0 frames)
HB [21:32:03] vfr: gained time: 0 (0 frames) (0 not accounted for)
HB [21:32:03] aac-decoder done: 36138 frames, 0 decoder errors
HB [21:32:03] h264_qsv-decoder done: 26 frames, 0 decoder errors
HB [21:32:03] sync: got 26 frames, 22855 expected
HB [21:32:03] sync: framerate min 5.001 fps, max 29.891 fps, avg 25.089 fps
HB [21:32:04] mux: track 0, 21 frames, 40966 bytes, 0.43 kbps, fifo 32
HB [21:32:04] mux: track 1, 38231 frames, 5473480 bytes, 57.27 kbps, fifo 65536
HB [21:32:04] Finished work at: Thu May 14 21:32:04 2026
HB [21:32:04] libhb: work result = 0
VC [21:32:04] Job completed (Elapsed Time: 2s)
VC [21:32:04] Job completed: ..4. Vector Dimensions.mkv
VC [21:32:04] Queue completed
VC [21:32:04] ""

[zakimimit]

When you uncheck all Intel QuickSync, the encoding process works properly. Check it because it is a critical bug that fails silently.

[RandomEngy]

Try it with HandBrake. VidCoder uses HandBrake for the core encoding engine, so if the issue reproduces there it's an issue with their code and you can ask them for help. If it doesn't reproduce with HandBrake, we know it's a VidCoder issue.

Equivalent versions:
VidCoder Stable ↔ HandBrake Stable
VidCoder Beta ↔ HandBrake Snapshots

[zakimimit]

@RandomEngy
It has already been tested with HandBrake and there were no problems; the problem only appears with VidCoder.

This problem is critical because it fails silently. For example, if you batch convert 100 videos, you cannot check them all, so it is easy to lose content.

[RandomEngy]

Could you provide a source file and the preset used to encode it? I don't think I'll be able to fix from the logs alone here.

You could also try the Beta version of VidCoder to see if it's been fixed.

[zakimimit]

• The beta version exhibits the same behaviour for the preset test on all QSV versions.
• The same problem occurs when you uncheck all Intel QuickSync; the encoding process only works properly when this is done.
• If I check the first or second option in Intel QuickSync, it does not work and produces a static video with audio.