problem when seeking with an mp4 file

[gal kahana]

Summary of the bug:
i am trying to created a version of seg_2_1_1.mp4 without the first half a second.
i am running the command "ffmpeg -y -i seg_2_1_1.mp4 -ss 0.5 -c copy seg_2_1_1_cut.mp4" to do this.
problem is the result is wrong. Seems like too much video is cut.
Checking with ffprobe i see that the output streams are desynched - the video stream is
shorter than the audio stream in about half a second, and is offset by 0.6 seconds.
i would like NOT to lose that extra half a second.

for some reason, when encoding, even just the video stream, doing something like this:
"ffmpeg -y -i seg_2_1_1.mp4 -ss 0.5 -c:a copy seg_2_1_1_cut.mp4"
The problem is solved. however, this takes more time, so i'd like to avoid.

How to reproduce:

% ffmpeg -y -i seg_2_1_1.mp4 -ss 0.5 -c copy seg_2_1_1_cut.mp4
ffmpeg version N-61105-gbba7b6f
built on  Mar  5 2014 22:01:31 with gcc 4.8.2

[gal kahana]

original mp4 file

[gal kahana]

result mp4 file

[gal kahana]

ffprobe output for original file

[gal kahana]

ffprobe output for result file

[Carl Eugen Hoyos]

The first GOP of your input stream has 33 frames (1.1 seconds), you cannot cut less frames with -vcodec copy.

For future tickets: Please do not attach output file or json output (unless requested), always provide your failing command line together with the complete, uncut console output (you only provided the command line).

[gal kahana]

mishap of mine (had the console output here). thanks a lot!