[FAQ]Cause: Failed to avio_open (error=-13)  

[FAQ]Cause: Failed to avio_open (error=-13)


This error can occur as a false alarm, if Avast software is running. When the error appears, press Allow App, and the error disappears and oCam will continue working any problem.


If the pop-up window asking wheter to allow app does not appear

Click the + ALLOW APP button in Menu -> Settings -> Blocked and Allowed Apps and select oCam to add it.

If oCam is added to the list of allowed apps, you will be able to record without any problem.


or, you can turn off Ransomware Shield off instead as follows.

Either way should be fine.

Additional tips

[Tips]Lossless recording-using x264vfw

* Before you begin, you need to install the x264 codec and you can find the instructions in the following link.


Click on CODEC menu of OHCAM and click on the external codec menu item.

Check Use External Codec, select the x264vfw codec and click the Settings button.

Based on the x264vfw default setting, change the yellow box in the figure below as shown.

The parts that are changed are as follows.

Preset-Ultrafast (Set to improve encoding speed and can increase file size, but other options will cause more racks.)

Profile-High 4: 4: 4 (Changes to High 444 for lossless encoding as the default profile may lose video quality.)

Keep input colorspace-Maintains the color space of the internally received buffer. (Other options may cause encoding to fail.)

Rate control-Single pass-lossless-Change for lossless encoding.

Press the OK button to apply the setting.

Since the settings are applied to x264vfw64 for 64-bit when recording 64-bit games, run x264vfw-Configure x264vfw64 from the Start menu and set them as shown above.

If you record with the above settings, you will be recording losslessly, where the important part is to change the settings of the video player to play lossless video losslessly.

The following shows how to check the lossless video based on the next pot player.

After launching the next pot player, click Preferences (F5).


In the environment setting window

Click Image-Colorspace / Properties on the left, and then select Convert directly if possible-Change to default output colorspace in the Colorspace group box on the right. (If this setting is not made, the color of the screen will be lost when playing the video even if the recording is lossless.)

Press OK and play the video recorded without loss.

At this time, if you press Ctrl + F1 on the next pot player, the video codec output format must be output in RGB (32 Bits) as shown below.

In addition, the properties below should be identical in the Playback Information-File Information tab as shown in the following figure.

Format profile: High 4: 4: 4 Predictive @ L3
Color space: RGB
Color range: Full
Matrix coefficients: RGB

Please note that Windows Media Player does not play properly and the preview thumbnail is not displayed in Windows Explorer.

Back to top