Video length is missing in old software after cobalt's live render

[wukko]

why does this happen?

to preserve privacy and maintain efficiency, cobalt merges & streams videos with ffmpeg right away, without ever storing or caching anything on disk.

as result, final file length cannot be predicted, so it's missing from headers of some downloaded files.

what's affected?

this happens only when live rendering is used, most often with youtube videos. older software (vegas pro, windows media player, default players on lower end android devices) cannot generate file length, so it's either missing or shows up as some obnoxious number like 4294967295.

what can be done about it?

at the moment, this is not something that can be fixed, as it's the nature of live rendering process.

however, in most cases, the issue can be worked around by using modern software instead. for playback, vlc media player can be used instead. other (and most accessible) playback option is the built-in media player in any modern web browser.

you can also "fix" files with missing timestamp by remuxing them with ffmpeg:

ffmpeg -i your_video_file_here.mp4 -c copy output_name_for_file.mp4

if you know how to solve this issue in cobalt's rendering pipeline, feel free to make a pull request!

previous related issues

these issues were closed in favor of this one, as they all describe the same problem, but in different apps:

• YouTube download has bugged time #94
• Missing preview image in macOS WhatsApp client #204
• Video scrubbing of YouTube videos does not work in outdated video players #255
• Windows Media Player won't play some videos #345
• Figure out why some DAWs don't like cobalt's .wav files #348
• Vegas Pro 18 breaks upon loading video higher than 720p (somehow even 480p)  #374
• Videos from cobalt have incorrect frame rate in VEGAS Pro #420
• File length isn't shown in Google Photos app #483
• Videos often downloading without timestamp #564

[ari-party]

I tried to replicate the described issue but I was unable to.

I downloaded 3 of the latest Fireship videos and the same for @homedesign369.
All videos showed the correct duration from ffprobe's input.duration.
And I was able to play all videos with the playback bar correctly showing the duration with Windows Media Player.

Could you possibly expand on what platforms (e.g. YouTube) this issue occurs on? And possibly link the videos for future contributors? (I won't be contributing to this issue.)