x264 decoding problem with the reference

[ryandevil]

Hi,

I used the reference H.264 decoder to decode a x.264 encoded bitstream, and the outcome is that the reference decoder cannot decode the bitstream.

I roughly looked at the bitstream, and found out that the NRI for SPS and PPS is set differently, as compared with the reference CODEC.

May I know why is this so?


Thank you very much.

Ryan

[bond]

split

[akupenguin]

What is NRI, and what x264 commandline produces output that JM doesn't like?

[ryandevil]

What is NRI, and what x264 commandline produces output that JM doesn't like?
Hi,

NRI stands for nal_ref_idc.

From the x264 encoded bitstream, it seems to me that the NRI for the first frame (I) is 10 (binary). As for referenced H264 encoded bitstream, the NRI is 11 (binary).

May I say that x264 and the reference H264 are 2 different CODEC, in the sense that x264 has its own set of syntax to follow?

Please advise.

Thank you very much.

[akupenguin]

x264 gives all IDR-frames nal_ref_idc=3 ("highest priority"). I have never had problems decoding x264 streams with JM.
If the first frame is an I and not an IDR, you must have cut a piece out of the middle of some video, and the error was in your choice of cutting point.

That said, if JM refused to play just because an IDR-frame has nal_ref_idc=2, that would be an error in JM. Because the standard only distinguishes between nal_ref_idc==0 vs nal_ref_idc!=0, while the different priority levels are entirely left to application-specific interpretation.