[FFmpeg-trac] #8106(undetermined:closed): Unexpected audio truncation with `-c:a copy`

[FFmpeg]

#8106: Unexpected audio truncation with `-c:a copy`
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             Reporter:  gdgsdg123    |                    Owner:
                 Type:  defect       |                   Status:  closed
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
                                     |  needs_more_info
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by gdgsdg123):

 Replying to [ticket:8106 gdgsdg123]:
 > Extra things I've tested:
 >
 > ...
 \\4. Matching the input/output framerate by adding `-framerate` option:
 {{{
 ffmpeg -loop 1 -framerate 15 -i "Entrepreneurship.png" -i "1.flac" -c:a
 copy -c:v libx264 -r 15 -vframes 3548 -preset placebo -qp 0 -x264-params
 "level=5.1:keyint=infinite:no-deblock=1" -pix_fmt yuv420p -sws_flags
 spline+accurate_rnd+full_chroma_int -color_range 1 -colorspace 5
 -color_primaries 5 -color_trc 6 "1.mkv"
 }}}
 No help.

 \\5. Greatly increasing `-vframes` to make the video duration much longer
 than the audio's.
 Helps, though there's another problem then...

 \\6. Removing `-vframes` and making necessary adjustments to the command:
 {{{
 ffmpeg -i "Entrepreneurship.png" -i "1.flac" -c:a copy -c:v libx264 -r 15
 -preset placebo -qp 0 -x264-params "level=5.1:keyint=infinite:no-
 deblock=1" -pix_fmt yuv420p -sws_flags spline+accurate_rnd+full_chroma_int
 -color_range 1 -colorspace 5 -color_primaries 5 -color_trc 6 "1.mkv"
 }}}
 The truncation no longer occurs, though again there's another problem...
 [[BR]]
 [[BR]]
 [[BR]]
 [[BR]]
 [[BR]]
 ...The cause seems to be `-vframes`/`-t`/`-to`/etc. interfering on `-c:a
 copy`.

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Ticket URL: <https://trac.ffmpeg.org/ticket/8106#comment:2>
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