[FFmpeg-devel] BUG? interlaced encoding using libx264, nal-hrd
erik at slagter.name
Mon Jul 18 19:50:34 CEST 2011
> I will try to resolve the complete issue though.
Okay, I seem to have find the origin of the issue.
FFmpeg apparently sets interlacing mode to bottom field first by default. The libx264
encoder is configured using tff=0 because of this. Then, when you're going to encode tff=1
material and you specify "tff=1" in the x264opts, the encoder is "reconfigured"
(x264_encoder_reconfig(x4->enc, &x4->params), line 120) now with value tff=1. If nal-hrd
is in use (this appears to be essential for interlaced encodings), libx264 complains with
the noted warning/error.
There seems to be a very simple workaround: add -top 1 to the ffmpeg command line (besides
x264opts "tff=1", which is also required).
So this is mostly a cosmetic issue, I don't know how this should be solved other than
changing the default interlacing mode of ffmpeg, but I guess that's unacceptable.
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