[FFmpeg-trac] #5440(avcodec:closed): nvenc with interlace video never create packets with AV_PKT_FLAG_KEY

[FFmpeg]

#5440: nvenc with interlace video never create packets with AV_PKT_FLAG_KEY
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             Reporter:  maf         |                    Owner:
                 Type:  defect      |                   Status:  closed
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:  invalid
             Keywords:  nvenc       |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Comment (by maf):

 Replying to [comment:10 heleppkes]:
 > FWIW I just tested, and adding -flags ildct does not change the number
 of keyframes in the output packets.

 I run the same command. My video is 1920x1080 25fps.
 In output MKV only the first packet has flags=K (checked by ffprobe).
 When I do the same with MOV output then all packets have KEY flag (again,
 ffprobe's report).
 This inconsistency is strange.

 > Maybe your GPU is not interlaced capable? It might make sense to test
 the capability in the NVENC encoder before trying to use it (through
 NvEncGetEncodeCaps with NV_ENC_CAPS_SUPPORT_FIELD_ENCODING)

 Added this check. The returned caps value is 1. Documented as "Interlaced
 field mode encoding is supported". Documentation also mentions value 2 =
 "Interlaced frame encoding and field mode encoding are both supported."

 I'll try another PC.

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Ticket URL: <https://trac.ffmpeg.org/ticket/5440#comment:11>
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