[FFmpeg-devel] [BUG] h264 picture reordering fails

Haruhiko Yamagata h.yamagata
Sat Jun 20 12:24:48 CEST 2009

>On Sat, Jun 20, 2009 at 02:02:01PM +0900, Haruhiko Yamagata wrote:
>>> On Thu, Jun 18, 2009 at 09:46:27PM +0900, Haruhiko Yamagata wrote:
>>>>> On Sun, May 31, 2009 at 05:51:33PM +0900, Haruhiko Yamagata wrote:
>>>>>>> On Sat, May 30, 2009, Haruhiko Yamagata wrote:
>>>>>>>>> On Sat, May 30, 2009 at 07:34:32PM +0900, Haruhiko Yamagata wrote:
>>>>>>>>>> I found picture reordering fails in
>>>>>>>>>> http://x264.nl/h.264.samples/premiere-paff.ts
>>>>>>>>>> Outputted pictures have POC {-4, -2, 4, 0, 2, 6}.
>>>>>>>>>> Are negative POCs allowed?
>>>>>>>>>> If yes, zero as POC is valid as well.
>>>>>>>>> about POCs, IIRC the spec requires POC=0 to be true and only true 
>>>>>>>>> for
>>>>>>>>> IDR pictures, but i might misremember (would have to check the spec)
>>>>>>>>> What i do know is that the POC or frame number == 0 rules in the 
>>>>>>>>> spec
>>>>>>>>> are not followed by some encoders.
>>>>>>>> Yes, I think POC=0 means IDR. In that case, negative values as POC 
>>>>>>>> are
>>>>>>>> not allowed.
>>>>>> On Sun, May 31, 2009, fenrir wrote:
>>>>>>> This point has been discusses on the JVT mailing list, it was said 
>>>>>>> that
>>>>>>> negative POC are valids, they just mean that the picture has to be 
>>>>>>> displayed
>>>>>>> before the IDR.
>>>>>> OK, I understand.
>>>>>> Then negative POC should typically be -2, while longer reference chains 
>>>>>> are theoretically possible.
>>>>>> Obviously it is not the case with mine. The frame with POC 0 happens to 
>>>>>> be a B frame.
>>>>> what POC value does the reference impl give that frame?
>>>>> If a B frame ends at POC=0 that seems a bug in the encoder and we should 
>>>>> find
>>>>> a way to handle that POC=0 non IDR case not chnage POC
>>>>> OTOH
>>>>> if the reference gives it a POC != 0 then our poc code is buggy
>>>> JM decoder gives POC=0 to the B frame. The log attached.
>>>> I extracted the bitstream from the GDR frame to the end.
>>>> If you need the .264 file I used to get the log, please let me know.
>>> could you try to remove all poc==0 checks related to picture ordering and
>>> just leave the IDR checks, maybe that would work? (also has to be tested
>>> against a few other streams ...)
>> OK, checking h->delayed_pic[i]->key_frame looks sufficient to detect IDR.
>> Patch attached.
>> I have checked rev 14347 and 15153. I also have read issue 576.
>> This change seems to be OK with cathedral-beta2-400extra-crop-avc.mp4.
>it seems you have missed
>cross_idr = !h->delayed_pic[0]->poc || !!h->delayed_pic[i] || h->delayed_pic[0]->key_frame;
>            ^^^^^^^^^^^^^^^^^^^^^^^
>or is there a reason why this is not changed?

I just missed it.
Patch updated.

Best regards,
Haruhiko Yamagata
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