[x264-devel] Decoder errors in x264 with JM 19

[BugMaster]

On Wed, 24 May 2017 17:19:45 +0530, Aishwarya wrote:
> Hi,

> Recently I ran some  simple encodes with x264 on 444 clips like
> old_town_cross_444_720p50.y4m using the following options. 

>  --preset medium --keyint -1 --x264weightp 0 --ref 6 

> When I try to decode the stream using a binary of JM Decoder 19 , I get this error

> warning: Intra_8x8_Vertical prediction mode not allowed at mb 16
> warning: Intra_8x8_Vertical prediction mode not allowed at mb 16
> warning: Intra_8x8_Vertical prediction mode not allowed at mb 16
> invalid 16x16 intra pred Mode HOR_PRED_16

> Has anyone faced this problem? The same stream is able be decode well with JM 18.5 binary.

> ...

> Pls let me know if these are issues with encoder or the  problem is at the decoder.

> Thanks

Hi. Sorry for such long delay answer.

Decoding of 4:4:4 clips issue is due x264 encoding to be out of specs.
But the problems with fixing it is that this will need fixing of
libav/ffmpeg decoders which are also out of specs and decode current
x264 bitstreams correctly. But if we will fix it that will force
decoder fix which can break decoding of old streams if we there
wouldn't some backward compatibility workaround. Same issue exist with
lossless encoding and 8x8dct (disabled sometime ago with lossless to
be in specs).

There is patches at sandbox repo (WIP) which fix x264 encoding
according to specs if you want to test it.

> Also, x264 is giving inconsistent outputs with the latest builds.

What do you mean by "inconsistent outputs" and with which settings
exactly?