What Compression does HERO4 Video Playback and Live Preview use when Sent Over HDMI?
For live feed, HERO4 cameras output uncompressed video over HDMI output.
For video playback, video is stored compressed on camera but upon playback video is uncompressed and output over HDMI.
How Much Latency is there in HDMI Live Preview from the HERO4 Camera?
You will generally see about a 2-3 frame delay when using HDMI live preview.
What's the color space of the HDMI output (i.e. RGB)?
The color space of the HDMI output is RGB in Rec. 709.
Does HERO4 Black play back 4K content to a 4K TV through HDMI?
No, it does not. 4k content will play back at 1080-60 on a 4K TV via HDMI.
To provide the best possible playback of your GoPro 4K video, you should use a 4K capable computer connected to a 4K monitor or 4K TV. If the computer is not 4K capable, the video will likely play back choppy.
The GoPro HERO4 cameras can output a max format of 1080/60 through the micro HDMI port, so if you're set in 4K, 2.7K, or 1440, the output resolution to the monitor or third party device will be 1080 at 60Hz.
The expected output signal is also dependent on the input device's supported input formats. If the HDTV monitor or device you're connecting to supports a maximum input of 1080/60p, the GoPro will want to output at highest input setting that best matches its video setting.
Most HDTV monitors support 720/60p and 1080/60p, so if you're set at the 720 resolution or lower, the expected output should be 720/60p. If you're set at a resolution of 960 or higher, the expected output should be 1080/60p. If your monitor or device supports an input of 1080/30p, and you're set at a resolution of 960 or higher at 30fps, then you should expect an output of 1080/30. Higher frame rates like 120 and 240 will default to 60Hz, since they are divisible by 60.