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If I execute a ffmpeg command from terminal, I get the desired result:

ffmpeg  -i src.mp4 -ar 22050 -ab 32 -f flv -s 320x240 video.flv

Terminal's output

... video:3404kB audio:1038kB global headers:0kB muxing overhead 2.966904%

And video.flv is created correctly.

Then, if called via PHP exec:

exec("ffmpeg  -i src.mp4 -ar 22050 -ab 32 -f flv -s 320x240 video.flv", $o, $v);

the output is:

array(0) { } int(1)

And no file is created.

Any thoughts on how to approach this?

I can exec('whoami') with no problems.

I have used the ffmpeg full path as well: /usr/local/bin/ffmpeg

share|improve this question
Maybe exec() only captures stdout in output, not stderr. – Oliver Salzburg Mar 24 '12 at 17:29
FFmpeg produces very weird output — you have to redirect both stdout and stderr to get everything AFAIK. – slhck Mar 24 '12 at 17:32
I do not get the desired flv file created, so something is def. not working. Definitively the most urgent matter at this point ;) – goliatone Mar 24 '12 at 17:34

add "2>&1" to the end of the command and it will work:

exec("ffmpeg  -i src.mp4 -ar 22050 -ab 32 -f flv -s 320x240 video.flv 2>&1", $o, $v);
share|improve this answer

right, the problem is that you use exec instead of shell_exec the point is that environement of exec don't know about any ffmpeg executable, but shell_exec does, becuase it uses env. of the bash/shell

Ths Solution use full path to ffmpeg executable, eg. /usr/bin/ffmpeg

share|improve this answer
No, the user said they tried /usr/local/bin/ffmpeg as well. – slhck Jul 17 '12 at 15:02
we had same issue half year ago, solution, described above, solved the problem, what about "/usr/local/bin/ffmpeg", maybe - bin folder is not correct !?.. – Rodislav Jul 17 '12 at 15:05

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