Opened 8 years ago
Last modified 8 years ago
#16031 new defect
Video capture on 4K monitors is broken; bitrate too low producing blurry video
| Reported by: | Technologov | Owned by: | |
|---|---|---|---|
| Component: | other | Version: | VirtualBox 5.0.26 |
| Keywords: | Cc: | ||
| Guest type: | other | Host type: | other |
Description
Host: Win 10, VBox 5.0.26, 1 monitor
Guest: Win 10, 1 monitor
Steps to reproduce:
- Requirements: one display with 4K / Ultra HD resolution (3840x2160)
- Setup video capture in your guests; Currently it's limited to 2880x1800 resolution and a joke bitrate of 2 Mbps.
Expected results:
- Video capture must support max. resolution of 4K (3840x2160) -and- 60 FPS -and- *much* higher bitrate.
- Bitrate table recommendations: 2 Mbps for HD 720p (1280x720) or 2.5 Mbps per Megapixel. 5 megapixel for FullHD (1920x1080), 20 megapixels for UltraHD (and 40 megapixels for UltraHD-at-60 FPS.)
You need to double the maximums for high quality rendering of text and for 60 fps and double bitrate again due to real-time encoding (which is much less accurate than slow video encoding). My suggestion is to allow for a 80 Mbps video capture. (at any resolution).
-Technologov, 5.10.2016.
Attachments (1)
Change History (3)
by , 8 years ago
| Attachment: | win10-2016-10-05-video-capture.log added |
|---|
comment:1 by , 8 years ago
Another point to note: While newer codecs like AV1 and Google VP9 are better than WebM/VP8 (as currently used by VBox) at slow encoding, for real-time encoding the difference appears to be small. So for now my suggestion is to keep VP8 codec.
comment:2 by , 8 years ago
Correction: 5 megabits (not megapixel) for FullHD (1920x1080), 20 megabits for UltraHD (and 40 megabits for UltraHD-at-60 FPS.) - recommended at slow-encoding speeds.
For real-time encoding, those bitrates must be doubled.
Vbox.log