Audio/video sync issues with mp4.

[toomanyblastedbits]

My cousin has some Dark Shadows episodes he asked me to burn to BD-R so he can watch on his TV via Sony Blu-Ray player. He told me the first files plays ok till about 15 min in and the audio get out of sync by as much as 6sec. I have same brand Blu-Ray player, but not model, but they are similar to what format they will play.

Video in question plays ok on my player till about 10min in and the audio gets out of sync by maybe 250ms. If I pause temporarily the audio gets back in sync. The files plays without problems on my PC with VLC. It appears the files may have been re-encoded from their original and I wonder if that causes there to be the issue playing them with the Sony player.

Suggestions if they need to be re-encoded with different settings?

Here is mediainfo.

Thanks.

General
Complete name : C:\Users\scoot\Videos\dark-shadows_202210\dark-shadows_202210\dark-shadows_202210\0001-Dark Shadows.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 560 MiB
Duration : 21 min 37 s
Overall bit rate mode : Variable
Overall bit rate : 3 620 kb/s
Writing application : Lavf59.24.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Baseline@L4.2
Format settings : 3 Ref Frames
Format settings, CABAC : No
Format settings, Reference frames : 3 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 21 min 37 s
Bit rate : 3 385 kb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 60.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.027
Stream size : 524 MiB (94%)
Writing library : x264 core 161
Encoding settings : cabac=0 / ref=3 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=24 / lookahead_threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=120 / keyint_min=12 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=crf / mbtree=1 / crf=21.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Codec configuration box : avcC

Audio
ID : 2
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 21 min 37 s
Source duration : 21 min 37 s
Bit rate mode : Variable
Bit rate : 226 kb/s
Maximum bit rate : 384 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 : 35.0 MiB (6%)
Source stream size : 35.0 MiB (6%)
Language : English
Default : Yes
Alternate group : 1

[ProWo]

Maybe a simple remux helps.

[poisondeathray]

Many older BD hardware chips will choke on Level 4.1 AVC. 1080p60 requires Level 4.2 . You can re-encode it to 1280x720p60 to be L4.1 compliant

It depends on which "Dark Shadows" series, but it's unlikely to be 60p in the first place. Another option would be to adjust it properly to the original framerate

[toomanyblastedbits]

It is the original TV series. According to the manuals, both my Player and My cousin's player supports MP4/AVC up to level 4.1. They both play the files, but is that the reason the audio gets out of sync?

I would agree it's not likely original 60p and not 1920/1080.

I am re-encoding various episodes with different resolutions/FPS and ask cousin to watch and give feedback if audio sync issues arise and which resolution look better.

Thanks.

[poisondeathray]

According to the manuals, both my Player and My cousin's player supports MP4/AVC up to level 4.1. They both play the files, but is that the reason the audio gets out of sync?

Very likely. Players with older chipsets will stutter , drop frames, and/or go out of sync . And it's L4.2 or is the most common cause. A very picky player will need you to use BD compatible encoding settings, including vbv-buffer settings . And if you author a disc, you definitely need to use BD compatible settings

I am re-encoding various episodes with different resolutions/FPS and ask cousin to watch and give feedback if audio sync issues arise and which resolution look better.

Simplest is to downscale 1280x720p60 , copy the audio . (AAC is not support on older models, but it wouldn't play at all, not just be out of sync if that was the case)

Proper content frame rate was probably 23.976p, and you'd probably want to decimate if it was a clean 3 frame, 2 frame duplicate pattern . But there can be other patterns, or maybe it underwent some messed up conversions along the way. You can post a sample if you're not sure what to do

[toomanyblastedbits]

I opened one of the episodes in Virtualdub2 and there are 75,739 frames in a 21min episode. Every frame is duplicated. I re-encoded several episodes with Any-Video-Converter-Free-Version MKV/MP4 at 1280x720 at 29.970 at original bit rate and with original audio. MPEG-4 Visual. Simple@L1


I was able to get 44 episodes on first Blu-ray. My cousin says they are playing fine so far without any sync problems.

I'll assume the Level 4.2 was the problem.

Thanks for all the responses.