MJPEG Stream Information
I am receiving a MJPEG Stream from my camera. When I look at the video data with an hex editor it seems that it doesn't contain any streaming information. I just see one raw JPEG after another, but no information about the framerate etc. .
Is the lack of any meta information normal for MJPEG or is it just related to the camera I am using? If there a no information about the stream, how can a player know how fast to play the video?
Answer
The lack of metadata is normal. IP Cameras typically send MJPEG as just that, one JPEG image after another as a stream. This is the most basic valid MJPEG file. If you were to take a bunch of jpegs, cat them together into a large, giant file, and feed it to ffmpeg, it would see it as a valid mjpeg format file. Some cameras will add an additional header to contain audio data, but it is not needed to be considered valid motion jpeg.
Many cameras will include a header like X-Framerate, in the HTTP header when the stream is initially sent, or you can set it as part of the camera configuration. However, when a camera sends only jpegs, there is no way to tell from the stream itself what the framerate is.