Sync Offset When Using PIX 240i/220i Audio Inputs with Camera Video
The PIX 220 and PIX 240 offer numerous choices for connecting audio signals.
- Embedded audio - this sends the camera's audio signals down the same SDI or HDMI connection as the video signal.
- Analog/digital (PIX 240 only) audio - this uses the audio inputs directly on the PIX recorder instead of, or in addition to, the embedded audio.
When a video camera is connected to the PIX 220 or PIX 240 over SDI or HDMI and analog or digital audio is directly connected to the PIX, the video signal is delayed with respect to the audio. This delay is caused by the processing required by the camera to convert picture to a digital video signal. This delay is unavoidable, and its duration is camera-dependent.
The delay can range from a single frame to five or six frames, depending on the camera and its settings. When recording with the PIX, this delayed video input causes an offset relative to the audio inputs directly on the PIX recorder. The remedy is to apply an audio input delay at the PIX. This audio delay compensates for the video delay introduced by the camera. With the correct delay set, video and audio will be in sync.
Below is a table indicating the input delay setting (milliseconds) required to compensate for different amounts of video delay. The top rows indicate the amount of video delay in frames and the left column corresponds to the frame rate being used. The boxes in gray are beyond the input delay limit of the PIX recorder. It is unlikely that a camera would introduce a video delay greater than 200 ms.
- If recording at 29.97 fps and experiencing a video delay of 3 frames, the audio input delay setting in the PIX should be set to 100 ms.
- If recording at 23.98 fps and experiencing a delay of 4 frames, the audio input delay setting in the PIX should be set to 167 ms.