How to Use the x264vfw External Codec
oCam supports external codecs (VFW), and here we will look at how to use the x264 codec.
You can download the x264 codec from the site below.
https://sourceforge.net/projects/x264vfw/
Go to the site and click the Download button.
The download will start automatically.
On the installation screens, just keep clicking Next.
Accept the license agreement.
Specify the installation path.
The installation is complete.
Click Finish.
After installing the codec, you must restart oCam before it will appear in the external codec list.
After restarting oCam, click the Codec button in the oCam main window, then click the External Codec menu.
Select the Use External Codec checkbox.
From the list, select x264vfw - H264/MPEG-4 AVC codec.
Then click the Settings button to view the detailed codec settings.
The codec settings window will appear as shown below. Since we need to record the screen in real time rather than perform normal video encoding, select Ultrafast in Preset and check the Zero Latency checkbox so that encoding is performed as quickly as possible, then click the OK button.
( This setting method is useful for real-time recording, and you can adjust it as needed depending on your situation. )
After configuring it this way, your recording will use the x264 codec.
* For game recording, if the game you want to record is 64-bit, you must also install the 64-bit version when installing x264vfw ( by default, it is installed automatically unless you change the installation options ). Then run x264vfw - Configure x264vfw64 from the Start menu and configure it the same way as described above.
* The x264vfw settings Keep/Accept only YUV 4:2:0, Keep/Accept only YUV 4:2:2, and Keep/Accept only YUV 4:4:4 are not supported, and recording will fail if you use those settings.
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FAQ About Variable Frame Rate (VFR) and Constant Frame Rate (CFR)
The following is a brief and clear FAQ about the frame rate modes in oCam.
Q. What exactly is Variable Frame Rate?
Variable Frame Rate (VFR) and Constant Frame Rate (CFR) are distinguished by the number of frames in the recorded video file. If the number of frames per second remains the same throughout a certain period of recorded video, it is considered Constant Frame Rate. On the other hand, if the frame count changes even for just one second during recording, it is classified as Variable Frame Rate. For example, if a screen is recorded for 5 seconds and every second is recorded at exactly 30 frames, it is Constant Frame Rate. However, if the video is recorded at 25 frames per second during the 3 to 4 second section of those 5 seconds, while the rest is recorded at 30 frames per second, it is Variable Frame Rate. However, the frame count in the final part of the video (for example, the last 0.5 seconds of a 4.5-second recording) is excluded when determining whether it is Constant or Variable Frame Rate. In other words, if a video was recorded for 4.5 seconds, stayed consistently at 30 frames per second for the first 4 seconds, and only the final 0.5 seconds had fewer than 30 frames, it is still regarded as Constant Frame Rate.
Q. If I record a game at 60 FPS in oCam with Variable Frame Rate mode enabled, and my system is powerful enough that there is no lag at all, will it be recorded as Constant Frame Rate?
If your system performance is good enough that no lag occurs during recording, then even if Variable Frame Rate mode is enabled, the result may still be recorded as Constant Frame Rate. This is because oCam is operating in an environment where it can accurately record all 60 frames per second. In other words, even in Variable Frame Rate mode, if the frame count remains consistent, the result will be the same as Constant Frame Rate. Therefore, if your system can stably maintain 60 FPS, the recorded video will be saved at a fixed 60 frames per second.
Q. I recorded a game in oCam at 60 FPS for 5 seconds, but exactly 30 frames per second were recorded (150 frames total). Is this Variable Frame Rate?
In this case, the recorded video is regarded as 30 FPS Constant Frame Rate. Even if oCam was set to 60 FPS, if only 30 frames per second were actually recorded consistently, the frame count is still constant, so it is classified as Constant Frame Rate. Variable Frame Rate applies only when the frame count changes during recording. Simply failing to reach the configured 60 FPS does not make it Variable Frame Rate. Therefore, in this case, a video file recorded consistently at 30 FPS is created.
Q. I recorded at 60 FPS in Variable Frame Rate mode, and the game was output at 60 FPS, so why does the recorded file show 59.xx FPS?
Even if the game is output at 60 FPS, the actual screen output may not occur at exact intervals of 16.66666666666667 ms (1000 ms รท 60). In most cases, the frame intervals are not perfectly uniform because of tiny differences measured in milliseconds. As a result, the recorded video may be displayed as 59.xx FPS. In addition, oCam calculates and displays FPS in 200-millisecond intervals, so even if it appears as 60 FPS on screen, it may actually be recorded as 59.xx FPS. To resolve this issue, change the setting in oCam to Constant Frame Rate mode before recording. Since Constant Frame Rate attempts to maintain the specified FPS, it can minimize these small differences.
Q. If my computer performance is low when recording in Constant Frame Rate mode, will it be recorded as Variable Frame Rate instead?
No. If you set it to Constant Frame Rate mode, it will still be recorded as Constant Frame Rate even if your computer performance is low. However, if system performance is insufficient, for example, when attempting to record at 120 FPS in Constant Frame Rate mode, the video file will still be created at 120 FPS, but the video quality may drop or severe lag may occur. This happens when the system is forced to maintain the specified frame rate and stuttering appears as a result. Therefore, on lower-performance computers, it is recommended to choose an appropriate frame rate or consider settings that reduce system load.