[FFmpeg-trac] #7426(undetermined:closed): [ffmpeg-qsv][avc encode] "-look_ahead_depth 100" cause "Cannot allocate memory"

FFmpeg trac at avcodec.org
Tue Sep 11 03:28:14 EEST 2018

#7426: [ffmpeg-qsv][avc encode] "-look_ahead_depth 100" cause "Cannot allocate
             Reporter:               |                    Owner:
  zhuqingliang                       |                   Status:  closed
                 Type:  defect       |                Component:
             Priority:  normal       |  undetermined
              Version:  unspecified  |               Resolution:  invalid
             Keywords:  qsv          |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
Changes (by jkqxz):

 * status:  new => closed
 * resolution:   => invalid


 Since libmfx does not support dynamic sizing of frame pools,
 extra_hw_frames is needed to set how many frames will be available in the
 pool created by hwupload which is then used at the encoder input.  Setting
 a high lookahead depth means the encoder will consume a large number of
 frames without returning them, so if extra_hw_frames is not large enough
 the pool will be exhausted as indicated by the error message above.

 Set extra_hw_frames to reflect how many frames you actually intend to use.
 With a lookahead depth of 100 you need at least 100, and probably more
 because the encoder will also store past frames to use for reference.

Ticket URL: <https://trac.ffmpeg.org/ticket/7426#comment:2>
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