Audio keeps going out of sync - not VFR

Bug
1

OS: Windows 10

Shotcut version: 20.04.12

I’ve got a few short clips which when played in MPC and VLC the audio is perfectly matched. When I import into Shotcut it plays fine in the Playlist window. I then add two video channels to add two logo overlays (PNGs). On export the audio is out of sync. I just use the audio from the original video clip, I haven’t added additional audio.

This is the MediaInfo output for the original:

General
Complete name : C:\Users\asher\Videos\EPAS\Exported\Cherwell School involvement.MP4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 45.6 MiB
Duration : 13 s 974 ms
Overall bit rate mode : Variable
Overall bit rate : 27.3 Mb/s
Encoded date : UTC 2021-06-16 14:57:18
Tagged date : UTC 2021-06-16 14:57:18
Writing application : Lavf58.45.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.2
Format settings : CABAC / 2 Ref Frames
Format settings, CABAC : Yes
Format settings, Reference frames : 2 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 13 s 940 ms
Source duration : 13 s 980 ms
Bit rate mode : Variable
Bit rate : 27.2 Mb/s
Maximum bit rate : 36.9 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 50.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.263
Stream size : 45.2 MiB (99%)
Source stream size : 45.3 MiB (99%)
Encoded date : UTC 2021-06-16 14:57:18
Tagged date : UTC 2021-06-16 14:57:18
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
mdhd_Duration : 13940
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 13 s 974 ms
Bit rate mode : Constant
Bit rate : 128 kb/s
Channel(s) : 1 channel
Channel layout : C
Sampling rate : 48.0 kHz
Frame rate : 46.875 FPS (1024 SPF)
Compression mode : Lossy
Stream size : 218 KiB (0%)
Default : Yes
Alternate group : 1
Encoded date : UTC 2021-06-16 14:57:18
Tagged date : UTC 2021-06-16 14:57:18

Any ideas for what might be causing this, or how I can get around it?

2

Hi: Although the audio track (audio 2) indicates constant, the video is VFR.
Did you try converting it to suitable for editing?
Does the same thing happen with the latest stable Shotcut version?

3

Thanks for getting back to me.

It says the frame rate mode is constant in the video (bit rate is variable):

Bit rate mode : Variable
Bit rate : 27.2 Mb/s
Maximum bit rate : 36.9 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 50.000 FPS

I didn’t realise that I didn’t have the most up to date Shotcut. I will update and try again.

1 Like
4

Just upgarded to most recent version (through MS Store to support development) and it’s all working fine!

Such an easy fix after hours of messing around. Not sure why I didn’t think of it myself!

1 Like
5

It is true. I was totally asleep. :sleeping:

Great. I’m glad it’s working for you. :slightly_smiling_face: