.....
#
(echo "Converting $FILE..."
sleep 5s
#
mv ${SRC_DIR}/${FILE} ${TRG_DIR}/${FILE}
#
THUMBNAIL="${USER_FOLDER}/${USER_ID}/video/${VIDEO_ID}.png"
ffmpegthumbnailer -i ${TRG_DIR}/${FILE} -o $THUMBNAIL -s ${THUMBNAIL_WIDTH}
#
mencoder ${TRG_DIR}/${FILE} -o "${TRG_DIR}/${FILE}.${OUTPUT_FORMAT}" ${PARAMS}
#
yamdi -i "${TRG_DIR}/${FILE}.${OUTPUT_FORMAT}" -o "${USER_FOLDER}/${USER_ID}/video/${VIDEO_ID}.${OUTPUT_FORMAT}" -c 'Your comment' -l
#
rm ${TRG_DIR}/${FILE}
rm "${TRG_DIR}/${FILE}.${OUTPUT_FORMAT}"
) &
...
Source: https://habr.com/ru/post/49053/