[VDPAU] ffmpeg and HEVC: Reference handling
José Hiram Soltren
jsoltren at nvidia.com
Tue Jun 2 13:33:22 PDT 2015
Hello Philip:
On 05/29/2015 12:45 PM, Philip Langdale wrote:
> I'm currently trying to work out what's going on with my reference
> handling. The code I have today seems to work perfectly fine for
> 'normal' files - certainly anything x265 or nvenc is willing to spit
> out, but it's not doing the right thing for some of the conformance
> samples.
Yes. The conformance clips are designed to exercise corner cases in the
Specification. Many encoders will avoid some of these parameters in practice.
> The code I've got seems to be internally consistent - I put all the
> short and long term refs into RefPics and I can match every entry in
> StCurrBefore/StCurrAfter/LtCurr back to those refs. And yet, I'm
> getting very visible glitching in the samples.
>
> Of course, for all I know, the glitching is unrelated to ref handling
> and is caused by some other feature being used by the samples. :-/
>
> I'm currently excluding all OUTPUT and 'bumping' entries from DPB from
> the RefPics[] array. I assume this is the right thing to do, but maybe
> that's a mistake?
>
> As for specific glitches, one that really stands out to me is if I try
> and decode RPS_C_ericsson_4.bit
I'm not able to find this one. We have a stream called RPS_C_ericsson_5.bit
internally:
$ sha1sum RPS_C_ericsson_5.bit
a148b9ec005bfcf82310cc01a5cef4ab6c05d90f RPS_C_ericsson_5.bit
The RPS_* bit streams test reference picture sets. Recall from the
Specification that the decoder must maintain a number of reference picture sets
and switch between them during decoding.
This is all more clear in the internal video playing application that I am
hoping to be able to release in the near future.
>, everything seems fine until I get to
> frame 23, at which point it suddenly outputs a frame that is
> bit-identical to frame 21 and then everything goes south from there. I
> don't know what to make of that.
Does the value of short_term_ref_pic_set_idx happen to change around frame 21,
22, or 23?
Thanks,
--José
> --phil
>
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