[Mp4-tech] Parameters for Selection of reference frames in JM

[Yiting LIAO]

Hello Alexis,
Thanks for the answer. I have another question:
poc_ref_pic_reorder is run only when EnableOpenGOP is set to 1. What does open GOPs mean? Can I just enable open GOPs and write the function you talked about to replace the original "poc_ref_pic_reorder" function and get the results? Thanks a lot. 
Yiting
Tourapis, Alexis wrote:
> Unfortunately there is no such option in the JM. What you need to do, apart from setting the 2nd picture to be coded as Intra, is to introduce reordering commands in the software that will basically select for coding for an odd positioned picture only previously coded odd positioned pictures, and similarly for an even positioned picture select again previously coded even ones. You can see an example of reordering that is based on POC distances in function slice.c (poc_ref_pic_reorder). What you need to do is write a similar function that orders references not on poc distance but in this scenario on whether poc (or frame number to be coded) is odd or even followed then by poc distance.
>
> I hope that helps.
>
> Alexis
>
> -----Original Message-----
> From: mp4-tech-bounces lists.mpegif.org [mailto:mp4-tech-bounces lists.mpegif.org] On Behalf Of Yiting LIAO
> Sent: Wednesday, January 23, 2024 6:06 PM
> To: mp4-tech lists.mpegif.org
> Subject: [Mp4-tech] Parameters for Selection of reference frames in JM
>
> Hello All,
>
> Is there a parameter that can be used to select reference frames used in the encoder. For example, odd frame only uses odd frames as reference frames and even frame only uses even frame as reference frames. If so, will the second frame in the video sequence be encoded into I-frame automatically? If not, which part should I modify to implement this function?
>
> Thanks,
> Yiting
>
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