Bug 507119

Summary: Audio thumbnail lagging behind actual audio
Product: [Applications] kdenlive Reporter: o.wertzberger
Component: Timeline & EditingAssignee: Jean-Baptiste Mardelle <jb>
Status: CONFIRMED ---    
Severity: wishlist    
Priority: NOR    
Version First Reported In: 25.04.3   
Target Milestone: ---   
Platform: Appimage   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Screenshot of Kdenlive timeline, showing a difference between embedded audio thumbnail and extracted audio thumbnail.
Kdenlive project showcasing audio thumbnail delay

Description o.wertzberger 2025-07-16 15:59:31 UTC 
Created attachment 183282 [details]
Screenshot of Kdenlive timeline, showing a difference between embedded audio thumbnail and extracted audio thumbnail.

SUMMARY
When working with a video file that has audio delay metadata, the audio thumbnail does not account for that delay, although playback does.

STEPS TO REPRODUCE
1. Import a video with delay metadata
2. Drag video onto editing timeline

OBSERVED RESULT
Audio thumbnail lags behind playback audio by the amount of time specified in the file's metadata.

EXPECTED RESULT
Audio thumbnail reflects the timing of audio during actual playback.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: 6.15.6
Qt Version: 6.9.1-4

ADDITIONAL INFORMATION
Below is the full MediaInfo details for the file shown in the attached screenshot. Of note is the value marked "Source_Delay":

General
Count :
359
Count of stream of this kind :
1
Kind of stream :
General
Kind of stream :
General
Stream identifier :
0
Inform :
MPEG-4 (Base Media): 5.63 GiB, 1 h 45 min
Count of video streams :
1
Count of audio streams :
1
Video_Format_List :
AV1
Video_Format_WithHint_List :
AV1
Codecs Video :
AV1
Audio_Format_List :
AAC LC
Audio_Format_WithHint_List :
AAC LC
Audio codecs :
AAC LC
Audio_Channels_Total :
2
Complete name :
/home/wheels/Videos/NormalOut.mp4
Folder name :
/home/wheels/Videos
File name extension :
NormalOut.mp4
File name :
NormalOut
File extension :
mp4
Format :
MPEG-4
Format :
MPEG-4
Format/Extensions usually used :
braw mov mp4 m4v m4a m4b m4p m4r 3ga 3gpa 3gpp 3gp 3gpp2 3g2 k3g jpm jpx mqv ismv isma ismt f4a f4b f4v
Commercial name :
MPEG-4
Format profile :
Base Media
Internet media type :
video/mp4
Codec ID :
isom
Codec ID :
isom (isom/av01/iso2/mp41)
Codec ID/Url :
http://www.apple.com/quicktime/download/standalone.html
CodecID_Compatible :
isom/av01/iso2/mp41
File size :
6049027444
File size :
5.63 GiB
File size :
6 GiB
File size :
5.6 GiB
File size :
5.63 GiB
File size :
5.634 GiB
Duration :
6334750
Duration :
1 h 45 min
Duration :
1 h 45 min 34 s 750 ms
Duration :
1 h 45 min
Duration :
01:45:34.750
Duration :
01:45:34:43
Duration :
01:45:34.750 (01:45:34:43)
Overall bit rate mode :
VBR
Overall bit rate mode :
Variable
Overall bit rate :
7639168
Overall bit rate :
7 639 kb/s
Frame rate :
60.000
Frame rate :
60.000 FPS
Frame count :
380083
HeaderSize :
32
DataSize :
6039565675
FooterSize :
9461737
IsStreamable :
No
File last modification date :
2025-07-13 22:32:45 UTC
File last modification date (local) :
2025-07-13 18:32:45
Writing application :
Lavf61.7.100
Writing application :
Lavf61.7.100
Video
Count :
391
Count of stream of this kind :
1
Kind of stream :
Video
Kind of stream :
Video
Stream identifier :
0
StreamOrder :
0
Inform :
7 509 kb/s, 1280*960 (4:3), at 60.000 FPS, AV1 (Main@L5.2)
ID :
1
ID :
1
Format :
AV1
Format :
AV1
Format/Info :
AOMedia Video 1
Format/Url :
http://aomedia.org/
Commercial name :
AV1
Format profile :
Main@L5.2
Codec ID :
av01
Duration :
6334717
Duration :
1 h 45 min
Duration :
1 h 45 min 34 s 717 ms
Duration :
1 h 45 min
Duration :
01:45:34.717
Duration :
01:45:34:43
Duration :
01:45:34.717 (01:45:34:43)
Bit rate :
7508752
Bit rate :
7 509 kb/s
Width :
1280
Width :
1 280 pixels
Height :
960
Height :
960 pixels
Sampled_Width :
1280
Sampled_Height :
960
Pixel aspect ratio :
1.000
Display aspect ratio :
1.333
Display aspect ratio :
4:3
Rotation :
0.000
Frame rate mode :
CFR
Frame rate mode :
Constant
Frame rate :
60.000
Frame rate :
60.000 FPS
FrameRate_Num :
60
FrameRate_Den :
1
Frame count :
380083
Color space :
YUV
Chroma subsampling :
4:2:0
Chroma subsampling :
4:2:0
Bit depth :
8
Bit depth :
8 bits
Scan type :
Progressive
Scan type :
Progressive
Bits/(Pixel*Frame) :
0.102
Stream size :
5945727524
Stream size :
5.54 GiB (98%)
Stream size :
6 GiB
Stream size :
5.5 GiB
Stream size :
5.54 GiB
Stream size :
5.537 GiB
Stream size :
5.54 GiB (98%)
Proportion of this stream :
0.98292
Writing library :
Lavc61.19.101 av1_amf
Writing library :
Lavc61.19.101 av1_amf
colour_description_present :
Yes
colour_description_present_Source :
Container
Color range :
Limited
colour_range_Source :
Container / Stream
Color primaries :
BT.709
colour_primaries_Source :
Container
Transfer characteristics :
BT.709
transfer_characteristics_Source :
Container
Matrix coefficients :
BT.709
matrix_coefficients_Source :
Container
Codec configuration box :
av1C
Audio
Count :
287
Count of stream of this kind :
1
Kind of stream :
Audio
Kind of stream :
Audio
Stream identifier :
0
StreamOrder :
1
Inform :
48.0 kHz, 2 channels, AAC LC
ID :
2
ID :
2
Format :
AAC
Format :
AAC LC
Format/Info :
Advanced Audio Codec Low Complexity
Commercial name :
AAC
Format settings, SBR :
No (Explicit)
Format settings, SBR :
No (Explicit)
Format_AdditionalFeatures :
LC
Codec ID :
mp4a-40-2
Duration :
6334750
Duration :
1 h 45 min
Duration :
1 h 45 min 34 s 750 ms
Duration :
1 h 45 min
Duration :
01:45:34.750
Duration :
01:45:34.750
Source duration :
6334294
Source duration :
1 h 45 min
Source duration :
1 h 45 min 34 s 294 ms
Source duration :
1 h 45 min
Source duration :
01:45:34.294
Source duration :
01:45:34.294
Bit rate mode :
VBR
Bit rate mode :
Variable
Nominal bit rate :
118514
Nominal bit rate :
119 kb/s
Maximum bit rate :
128000
Maximum bit rate :
128 kb/s
Channel(s) :
2
Channel(s) :
2 channels
Channel positions :
Front: L R
Channel positions :
2/0/0
Channel layout :
L R
Samples per frame :
1024
Sampling rate :
48000
Sampling rate :
48.0 kHz
Samples count :
304068000
Frame rate :
46.875
Frame rate :
46.875 FPS (1024 SPF)
Frame count :
296941
Source frame count :
296920
Compression mode :
Lossy
Compression mode :
Lossy
Source stream size :
93838135
Source stream size :
89.5 MiB (2%)
Source stream size :
89 MiB
Source stream size :
89 MiB
Source stream size :
89.5 MiB
Source stream size :
89.49 MiB
Source stream size :
89.5 MiB (2%)
Source_StreamSize_Proportion :
0.01551
Default :
Yes
Default :
Yes
Alternate group :
1
Alternate group :
1
Source_Delay :
456
Source_Delay_Source :
Container
Comment 1 o.wertzberger 2025-07-16 16:01:33 UTC 
Additional information can be found in the forum thread this was first reported to: https://discuss.kde.org/t/audio-thumbnail-lagging-behind-actual-audio/37027
Comment 2 Jean-Baptiste Mardelle 2025-07-16 16:47:02 UTC 
Thanks for your report. Could you please also include the output of this command in a terminal;:
ffmpeg -i yourvideo.mp4
or a short sample file reproducing this problem ?
Comment 3 o.wertzberger 2025-07-16 18:19:21 UTC 
Created attachment 183286 [details]
Kdenlive project showcasing audio thumbnail delay
Comment 4 o.wertzberger 2025-07-16 18:20:39 UTC 
ffmpeg outputs the following on the original file: 

ffmpeg version n7.1.1 Copyright (c) 2000-2025 the FFmpeg developers
  built with gcc 15.1.1 (GCC) 20250425
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-frei0r --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libdvdnav --enable-libdvdread --enable-libfreetype --enable-libfribidi --enable-libglslang --enable-libgsm --enable-libharfbuzz --enable-libiec61883 --enable-libjack --enable-libjxl --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libplacebo --enable-libpulse --enable-librav1e --enable-librsvg --enable-librubberband --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpl --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-vapoursynth --enable-version3 --enable-vulkan
  libavutil      59. 39.100 / 59. 39.100
  libavcodec     61. 19.101 / 61. 19.101
  libavformat    61.  7.100 / 61.  7.100
  libavdevice    61.  3.100 / 61.  3.100
  libavfilter    10.  4.100 / 10.  4.100
  libswscale      8.  3.100 /  8.  3.100
  libswresample   5.  3.100 /  5.  3.100
  libpostproc    58.  3.100 / 58.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'NormalOut.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomav01iso2mp41
    encoder         : Lavf61.7.100
  Duration: 01:45:34.75, start: 0.000000, bitrate: 7639 kb/s
  Stream #0:0[0x1](und): Video: av1 (libdav1d) (Main) (av01 / 0x31307661), yuv420p(tv, bt709, progressive), 1280x960, 7508 kb/s, SAR 1:1 DAR 4:3, 60 fps, 60 tbr, 15360 tbn (default)
      Metadata:
        handler_name    : VideoHandler
        vendor_id       : [0][0][0][0]
        encoder         : Lavc61.19.101 av1_amf
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 118 kb/s (default)
      Metadata:
        handler_name    : SoundHandler
        vendor_id       : [0][0][0][0]
Comment 5 Jean-Baptiste Mardelle 2025-07-17 10:53:37 UTC 
Git commit 0369eebedf368d02034d92105d01a2996787f78a by Jean-Baptiste Mardelle.
Committed on 17/07/2025 at 10:53.
Pushed by mardelle into branch 'master'.

Audio thumbnails for files with an audio delay are not correctly geenrated with the libav generator

M  +8    -0    src/jobs/audiolevels/generators.cpp

https://invent.kde.org/multimedia/kdenlive/-/commit/0369eebedf368d02034d92105d01a2996787f78a
Comment 6 Jean-Baptiste Mardelle 2025-07-17 11:01:18 UTC 
Git commit 79d454b1aca8100d8d9578b466f693bb0c6e9779 by Jean-Baptiste Mardelle.
Committed on 17/07/2025 at 10:55.
Pushed by mardelle into branch 'release/25.08'.

Audio thumbnails for files with an audio delay are not correctly geenrated with the libav generator

M  +8    -0    src/jobs/audiolevels/generators.cpp

https://invent.kde.org/multimedia/kdenlive/-/commit/79d454b1aca8100d8d9578b466f693bb0c6e9779