mp4 files - audio out of sync

[pandalina]

Hey everyone. Here is an interesting puzzle for you: I have over 200 mp4 files all shot on the google pixel 3xl phone in 4k. All of these have audio out of sync by about 0.35 sec. How could I batch fix the sync issue? HandBrake doesn't seem to be helping as in cases with various framerates.

[davexnet]

To get the full file info, open the file with mediainfo, put it in text view, and add the info to this thread

[pandalina]

To get the full file info, open the file with mediainfo, put it in text view, and add the info to this thread

Thanks so much!

General
Complete name : D:\PXL_20211028_174319619.mp4
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42 (isom/mp42)
File size : 49.5 MiB
Duration : 9 s 15 ms
Overall bit rate : 46.0 Mb/s
Encoded date : UTC 2021-10-28 17:43:30
Tagged date : UTC 2021-10-28 17:43:30

Video
ID : 2
Format : HEVC
Format/Info : High Efficiency Video Coding
Format profile : Main@L5.1@Main
Codec ID : hvc1
Codec ID/Info : High Efficiency Video Coding
Duration : 9 s 15 ms
Bit rate : 45.9 Mb/s
Width : 3 840 pixels
Height : 2 160 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 28.175 FPS
Minimum frame rate : 3.006 FPS
Maximum frame rate : 30.070 FPS
FrameRate_Real : 30.000 FPS
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Bits/(Pixel*Frame) : 0.196
Stream size : 49.3 MiB (100%)
Title : VideoHandle
Language : English
Encoded date : UTC 2021-10-28 17:43:30
Tagged date : UTC 2021-10-28 17:43:30
Color range : Full
Color primaries : BT.601 PAL
Transfer characteristics : BT.709
transfer_characteristics_Original : BT.601
Matrix coefficients : BT.601
Codec configuration box : hvcC

Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 8 s 976 ms
Bit rate mode : Constant
Bit rate : 192 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 : 210 KiB (0%)
Title : SoundHandle
Language : English
Encoded date : UTC 2021-10-28 17:43:30
Tagged date : UTC 2021-10-28 17:43:30

[davexnet]

The file shows

Frame rate mode : Variable

Does it play back properly on the phone? Perhaps you can upload a smal sample

[pandalina]

The file shows

Frame rate mode : Variable

Does it play back properly on the phone? Perhaps you can upload a smal sample

It looked fine on the phone, but it's a small screen.

[davexnet]

My PC is too slow to properly play this file, so I played it on my TV via the DLNA network.
The audio follows the video properly, but may be a fraction, I don't think it's as much as a 1/3 of a second, early

Is this what you see?

Is this re-encoded version in sync?

[pandalina]

My PC is too slow to properly play this file, so I played it on my TV via the DLNA network.
The audio follows the video properly, but may be a fraction, I don't think it's as much as a 1/3 of a second, early

Is this what you see?

Is this re-encoded version in sync?

You are right it's about -150ms. This is one of the original files.

[davexnet]

Yet in the re-encoded version above, the sync is better (or so it appears to me).
I did not adjust the sync at all, just re-encoded the video and copied over the existing audio

If you want to experiment with an audio offset, get FFmpeg and test with this command. This example delays audio for 200ms

ffmpeg -i source.mp4 -itsoffset 0.200 -i source.mp4 -map 0:v -map 1:a -c:v copy -c:a newfile.mp4

[pandalina]

Yet in the re-encoded version above, the sync is better (or so it appears to me).
I did not adjust the sync at all, just re-encoded the video and copied over the existing audio

If you want to experiment with an audio offset, get FFmpeg and test with this command. This example delays audio for 200ms

ffmpeg -i source.mp4 -itsoffset 0.200 -i source.mp4 -map 0:v -map 1:a -c:v copy -c:a newfile.mp4

Thank you so much for your help. I figured out that the audio delay was caused by my Bluetooth-connected speakers. Switched to the hardwired setup - all good. Sorry for your time, but I still learned a lot!

[davexnet]

Yet in the re-encoded version above, the sync is better (or so it appears to me).
I did not adjust the sync at all, just re-encoded the video and copied over the existing audio

If you want to experiment with an audio offset, get FFmpeg and test with this command. This example delays audio for 200ms

ffmpeg -i source.mp4 -itsoffset 0.200 -i source.mp4 -map 0:v -map 1:a -c:v copy -c:a newfile.mp4

Thank you so much for your help. I figured out that the audio delay was caused by my Bluetooth-connected speakers. Switched to the hardwired setup - all good. Sorry for your time, but I still learned a lot!

yes this doesn't surprise me, especially since these files are straight out of the phone and should be good.
Even in my case, playing over the network, it was so close it was questionable if it was just a performance problem.

2nd clue is the video reencode/audio passthrough to a less demanding file, no problems there