errors when decode H.264 frames using ffmpeg

Question

I am getting the following errors when decoding H.264 frames received from the remote end of a H.264 based SIP video call. Appreciate any help in understanding there errors.

Answer 1

That just means that ffmpeg has not seen a keyframe yet, which carries SPS and PPS information. SPS and PPS are crucial in decoding an incoming frame/slice. Keyframes are sent periodically(i.e. every 5-10 seconds or more); so if turns out that you joined a stream before the keyframe arrived; you will see this warning for every frame until a keyframe shows up.

As soon as the keyframe shows up from the wire, ffmpeg will have enough information to decode that frame(and any subsequent frames until the next keyframe), so those warnings will go away.