Fusion doesn't detect audio for videos 47 minutes or longer

I have a collection of long H.264 MP4 video+audio files, each of which is about 3 hours. If I place any portion of that MP4 onto a timeline, either the full file or just a few seconds as a small clip, and then switch to the Fusion tab, the audio within the clip is not detected, ie no audio displayed for MediaIn1 in the keyframes panel inside fusion. And no audio is heard on playback within the same fusion tab.

However, if I create a subclip from those same media files and that subclip is approximately 46 minutes or shorter then the fusion tab properly detects the audio. If the subclip is 47 minutes or longer then fusion doesn't recognize the audio.

Also, for a subclip that is 46 minutes or shorter that properly displays audio in Fusion, if I then enable that subclip's "Use full clip extents" the audio for the clip stops being detected in the fusion tab.

FYI, each MP4 has an average bitrate of 930kbps, in case this issue is related to the clip size (bytes) rather than the clip length.

This is with Resolve 17 Beta 7 (Windows).

There seems to be a general problem with long mp4 files with AAC sound. I can't hear the sound if I cut such a file or a part of in into a timeline, even without going to the Fusion page. The sound is audible in the source page, but not from the timeline.
Other shorter sources with the same codecs are audible when cut into the timeline.

I can play the same file just fine in 16.2.8.

What camera created the files, Adam?

What camera created the files, Adam?

Hi Jim - the MP4's were downloaded off YouTube (via youtube-dl).

Mine are from German public TV official 'Mediathek' and I've been doing short excerpts for teaching purposes all the time in version 16.

the MP4's were downloaded off YouTube

Try it with proper camera originals. Report back.

Aren't most cameras which do mp4 overheating before reaching 48 minutes?

GH5 doesn't.

Don't know about others.

But...I probably wouldn't include any H.264/5 as a "proper camera original". RAW, ProRes, DNx...those are where my head's at.

the MP4's were downloaded off YouTube

Try it with proper camera originals. Report back.

Is there a known issue with Resolve's handling of MP4s generated by YouTube's system?

It seems you just discovered it.

Upvote. No idea how to +1.

I tried working around this issue by rendering the full video, and using that render. Nope. Still no audio.

Any other work around?

Hi, I'm new here and a new-ish user. I discovered this problem last night when trying to edit a video I'd done earlier this year.

Being new to the software, issues like this tend to make you assume that it's something you're doing wrong, so I spent an evening importing videos of different lengths (all exports from Resolve) and looking for the point it fails, after checking every audio setting I could.

A work-around would be good (I'll try rendering the raw video in 45 minute sections and re-import), but a fix would be even better


Richard

I took a previously rendered 72-minute long video that is silent in Fusion, cut in in half and exported both sections. Then I brought the two sections in and audio is fine in Fusion for both clips.

Then I made a new compound clip from the two clips and opened that in Fusion and no sound.

The source material is my own screen recordings from OBS.


Richard

CFR or VFR? Check with MediaInfo for free.

CFR or VFR? Check with MediaInfo for free.

CFR - the file was rendered in Resolve. Here's the stats from MediaInfo:

Code: Select all

ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Main@L4
Format settings                          : 2 Ref Frames
Format settings, CABAC                   : No
Format settings, Reference frames        : 2 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 1 h 12 min
Bit rate                                 : 2 697 kb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 30.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.043
Stream size                              : 1.36 GiB (93%)
Encoded date                             : 2024-01-22 16:01:57 UTC
Tagged date                              : 2024-01-22 16:01:57 UTC
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709
CodecConfigurationBox                    : avcC


Here are the audio stats, too

Code: Select all

ID                                       : 2
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 1 h 12 min
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                              : 101 MiB (7%)
Default                                  : Yes
Alternate group                          : 1
Encoded date                             : 2024-01-22 16:01:57 UTC
Tagged date                              : 2024-01-22 16:01:57 UTC


I'd have thought that if it were down to VFR, the clip length that the audio stops working would change with different files, but it seems that 47 minutes is the magic number.


Richard

That's weird and points to a specific memory error.

Edit:
I tried with a recording in AVC from another camera, and you are right! I'll have to narrow down when it stops, but something is wrong for sure.

I'll try with 19.

That's weird and points to a specific memory error.

To exclude the camera, can you get any other mp4 that long to try?

I didn't use a camera. The original source is a screen recording taken with OBS of one of my lectures that I had previously exported in DR, so those statistics are from a DR render that loses audio in Fusion, not the OBS file.

I'll render a simple 10 minute animation with audio this evening, so no external software. Then I'll keep adding it to itself and make compound clips to see what happens when the clip goes from 40 to 50 minutes.

A memory error seems unlikely, given that I'm replying to a thread where other users have experienced the same 47 minute problem on their systems over three years. We wouldn't all have the exact same memory fault.


Richard

OK, I could reproduce the issue in 19b3.
Up to 45 minutes I can play the clip with audio, a clip with 50 minutes has no audio from the start.
If the clip is under 45 minutes, I can click anywhere in the first 10 minutes or so, and the audio plays. If I click later, I have to wait 2-3 seconds until it plays. If I click too fast into a later part, DR crashes to the desktop.

This may even help the developers, so here's the log:
https://drive.google.com/file/d/1Oxetd7 ... share_link