Picture
The picture stays black
qBlank says in the picture what it sees:
- No signal: is the console on, and is Source → Card input the connector it is plugged into?
- The card is receiving noise only: check the cable and the input.
- Already in use by another program: most cards hand their picture to one program only. Close OBS, the manufacturer's tool or a second qBlank. qBlank keeps trying by itself.
- Not found: is the card plugged in? Then Refresh under Source.
F5 restarts the capture, Shift+F5 reinitialises the card.
No colour, or the wrong colours
Source → Video standard on Automatic, then F7. If it mixes up PAL 60 and NTSC, set the region below it to where you live.
Black looks grey, or crushed
F6 measures the range again, or set Range in Picture → Colour by hand. It often happens after an option was changed in the card's driver.
Lines comb apart when something moves
Turn on deinterlacing in Picture → Fields. If the picture then jumps up and down, switch the Field order.
Is a filter to blame?
Shift+F12 turns all filters off and shows the signal as it arrives. F12 splits the picture into with and without.
Sound
No sound
- Source → Source audio: Use the video device's embedded audio, or the right recording device.
- Audio → Playback: the right output device.
- M mutes. If Input level under Audio → Volume does not move, nothing arrives from the card.
Sound out of step with the picture
Audio → Delay → A/V offset. Positive delays the sound. Negative delays the picture and adds input lag.
Crackling or dropouts
Raise the Audio buffer under Audio → Delay. 20–40 ms is typical.
The card
“Connection lost”
The card dropped out, for example over a loose USB cable. qBlank reconnects by itself as soon as it is back.
The card hangs
Some drivers hang when the input is switched many times in quick succession, so switch calmly. If qBlank hangs along with the card, do not end it in Task Manager: killing it while it holds the card can lock the driver until Windows restarts. Restart the PC instead.
Recording
Recording does not start
Recording needs ffmpeg: Encoder → Download ffmpeg. If the chosen encoder does not work on this PC, qBlank goes back to Automatic. Test encoders shows which ones work.
“Encoder overloaded”
Pick a faster Preset, or a lower resolution or frame rate. A hardware encoder (NVENC, Quick Sync, AMF) takes the load off the CPU.
The MP4 will not open
An MP4 that was not closed properly, after a crash for example, cannot be opened. MKV survives that. Record to MKV and turn it into MP4 afterwards with Recording → Rewrap to MP4: seconds, and no quality lost.
Recording stopped by itself
The disk was nearly full. The Recording tab shows the free space as recording time. On a FAT32 drive, turn on Split at size: no file there can pass 4 GB.
Virtual camera
It shows a notice instead of the picture
qBlank is not running, or the camera is not turned on under Recording → Virtual camera.
Squashed or cut off after the source changed
A program picks the format when it opens the camera and keeps it. Open the camera again in that program.
“Points nowhere”
qBlank was moved after the camera was installed. Install it once more.
Input lag
How do I get the lowest latency?
- VSync off under Display → Graphics. It can tear.
- An uncompressed Colour format under Source. MJPG costs latency.
- No negative A/V offset: that delays the picture.
F1 shows how long a frame spends inside qBlank.
Still stuck
Report a bug
Turn on Write a log to qBlank.log under General → Other, make the problem happen, then open an issue with qBlank.log attached. About → Report a bug leads there too.
Start over with default settings
Close qBlank and rename or delete qBlank.json beside the program.