[FFmpeg-devel] extracting previous P frame from DPB [h264]

[Mehdi Hosseini]

Suppose a sequence in h264 is IBB*P*BBPB*B[*P]BBP

How can I extract the previous (in the display order)
 AV_PICTURE_TYPE_P frame of the current  slice from the DPB list? how about
extracting both next and previous (in the display order) of a
AV_PICTURE_TYPE_B slice?

for example, for the input of the third AV_PICTURE_TYPE_P slice of a
sequence ( in the bracket in the above example), I want to extract the
second AV_PICTURE_TYPE_P picture of the sequence form. Is that possible?

the place that I want to do it is  after  the line

>      if ((err = ff_h264_decode_slice_header(h, sl)))


in the function

> static int decode_nal_units(H264Context *h, const uint8_t *buf, int
> buf_size,
>                             int parse_extradata)

in the file h264.c


thank you.